Read the most frequently asked 80 top Astronomy multiple choice questions and answers PDF for freshers and experienced. Astronomy objective questions and answers pdf download free..
Astronomy Multiple Choice Questions and Answers PDF Experienced Freshers
1. How far away from earth, is space?
In fact, space is said to begin just 100km above the surface of the earth so if you were in a rocket then you would not need to travel for too long to hit space.
When you look in the sky to the moon for instance you actually only need to travel a tiny, tiny fraction of the way to the moon to enter space.
2. How does gravity affect life on Pluto?
Well, there is much less gravity no Pluto than there is on the planet Earth.
Therefore, it is easier to jump for instance a jump would take you much higher. Your body would also not need the robustness that it needs to deal with gravity here pushing down on your organs and so on, so might need to be less sturdy.
3. How do clouds form?
Clouds are formed as part of the water cycle. Effectively, warm air rises. Indeed, water vapor rises, as it is lighter than air.
However, as it rises through the sky, higher and higher up, the air is colder.
This causes the water vapor to condense and it turns to liquid droplets. This is what causes a cloud to form and condense.
When the density is high enough, the water escapes from the cloud and falls to earth as a cloud.
4. How did the moon form?
Theories abound. The most widely accepted thought at present is that some massive impact on earth in its very formative days was so violent that it sent a chunk of earth rock flying out into space, and this became the moon. Certainly if true, this was very fortuitous for life on earth in the end, as the moon has many effects on the earth that are beneficial for life, e.g. tides.
5. How can space expand faster than the speed of light?
Although nothing can travel faster than the speed of light, when space is expanding itself then things can move further than light does in a period - this is because it is not a particle that is traveling it is the fabric of space itself.
Space can expand at a rate that has not been determined but will not expanded to be bound by the movement of light or particles, so if the fabric of space itself expands then things can effectively be moved apart from each other at faster than light speed without themselves exceeding the limit.
6. How big is Venus?
In terms of size, Venus is the most like Earth, although not in terms of planetary conditions, climate, or hospitability for life.
Venus is 95% the size of earth. In terms of the density of the planet, it is very close to earth. It is 30% closer to the Sun than the earth is. It is also incredibly hot - around 880 degrees Fahrenheit at times, and sulphuric acid rain. The planet has a runaway greenhouse effect problem.
7. How big is the universe?
There is an edge to what we are able to see in the universe. The most distant galaxies we can now see are 10 or 12 billion light-years away. We could never see a galaxy that is farther away in light travel time than the universe is old, e.g. estimated 14 billion years. Thus, we are surrounded by a "horizon" that we cannot look beyond that. This horizon describes the visible universe—a region some 28 billion light years in diameter.
8. Does time stop at an event horizon?
You may have read that as you approach the event horizon of a black hole, time will stop for you.
Indeed, for any observers, it will appear that you go slower and slower and never quite reach it (ignoring the problems that you would be crushed to death by the gravity!)
However, if your watch were still to work, you would look down and perceive time to be passing as normal.
It is due to the immense gravity that the light you emit takes longer and longer to reach the external observer.
9. Does non-carbon based life exist somewhere in the universe?
No one can say no in answer to this, because we do not know what else is out there.
However, it seems likely that due to its chemical properties that life elsewhere would need to be based on carbon if it was of any size, although we cannot say for sure.
There are not that many elements that seem to have the flexibility that carbon does, the stability and abundance... however it is possible that something like silicon could perhaps be a candidate for life forms elsewhere; for very simple life forms there might be a larger range of candidate elements.
10. Do galaxies interact?
Of course we have no direct evidence of galaxies interacting but it does appear that they can and do, and are at this very moment, interacting.
Usually a violent and energetic affair, galaxies interacting will cause much destruction of existing material and then result in a product phase of much star formation and activity as the repercussions are felt throughout the galaxy.
11. Do black holes really exist?
As far as we can tell, they do exist, yes. Whilst no one has directly seen a black hole, they are of course dark objects so light cannot be seen; the effects of them can be seen.
Specifically the massive gravitational field and its impact can be observed at the centre of galaxies where the orbits of stars and matter do all sorts of crazy things from the intense gravitational pulls, so objects that behave consistently with the behavior of black holes at the centre of galaxies have had their predictions confirmed, yes.
12. Did water come from comets?
One interesting theory is that most of the water came to earth from comets.
The idea is that loads of small comets, about the size of small houses, come into the atmosphere every day.
They vaporize in the atmosphere, leaving their water behind.
The idea is that 10 of these very minute for billions of years over the course of the history of the planet would lead to virtually all the water in the oceans and atmosphere!
This would be significant, as it would give an alternative explanation for the standard idea that the water came from gaseous emissions from the crust of the Earth in the early days post its initial formation...
13. Describe the Venus atmosphere.
Venus has a very strange atmosphere, compared with the similar sized planet next to it - Earth.
The atmosphere is virtually all carbon dioxide - in the region of 9%. The rest is mainly made up of nitrogen. There is thick cloud made of not water but acids like sulphuric acid - nasty stuff indeed.
The pressure is massive in the atmosphere of planet Venus - indeed Venus would crush us, as it is 90 times that of earth!
The temperature on Venus is also massive, around 500 Celsius - even some metals would be liquid on the surface of Venus!
14. How far from earth, is the moon?
The Mean Distance of Moon from Earth is 238,712 miles (384,400 km).
The greatest distance is 252,586 miles.
The shortest distance is 221,331 miles.
Interestingly, the Moon used to be much closer to the earth, and may have had a pivotal role in the evolution of life on the planet and the whole history of the planet before us, that led to our creation.
The implication of this is also that the Moon will not always be with us - the Earth is slowly losing its grip on the Moon and at some stage long, in the future, the Moon will actually escape Earth's gravitational pull and out of Earth's gravitational grasp.
15. How fast is the solar wind?
A very interesting questions this about the speed of the solar wind. This depends on conditions in and around the sun and how particularly active it is at the time and therefore varies greatly. It moves between around 200 to 900 kilometers per second.
16. How have some stars had time to die since the universe began?
This often confuses people that there are stars that have been through their entire life cycle yet there are many stars still forming.
Well part of the answer is that a large star burns quicker and dies quicker so might have its whole life cycle in the fraction of the time a star as if our own Sun does which is perhaps mid sized.
Therefore, it might take a billion years for a large star to go through its lifecycle and if stars started to form around a billion years after the big bang, then after 2-3 billion years stars could have burnt out, thus they could have died already.
17. How is Saturn like earth?
Saturn is like earth in the sense that it is one of the planets of the solar system.
Earth is also a planet. They also both are alike in that they go around the sun.
Also they both have moons, though earth has just one and Saturn has so many that we still don't know what they all are and more and more are being found around Saturn all of the time.
Therefore, in these ways they are similar.
18. How is Venus different to earth?
Venus is different to planet earth in quite profound ways. We focus, being alive, on the fact that Venus could surely not support life. This focuses us in on some massive differences between the two planets.
First, up, Venus rotates extremely slowly compared to earth.
It also has a magnetic field that is almost non-existent - not good for life! Of course, the temperature means it is so dry and there is hardly any water.
There is extreme pressure on the surface and temperature, and the atmosphere is very dense with a run away greenhouse effect.
19. How is Venus like Earth?
Venus is like Earth in some ways, mainly cosmetic, but very different in others.
However until we studied Venus in general it was thought to be a sister planet but the reality is very different. In terms of similarities are the two main facts:
1) It is the closest to Earth in the solar system, very close indeed in planetary terms
2) The second thing is that it is a small rocky planet, of almost the same size as earth
However as you will see in the differences to Earth question I just answered, the differences between the two planets Earth and Venus are much more profound than the similarities.
20. How long is a day on Saturn?
A day on Saturn is hard to measure, however scientists now believe that the value of a day on Saturn in terms of length is around 10 hours and as such being ten hours compared to our 24 it is less hours than a day on earth.
21. How long is a year on Saturn?
Saturn is much further from the Sun than the Earth is. Therefore, for it to complete its orbit around the sun once takes much longer than for Earth due to the much wider circle it has to go around in order orbiting (well, ellipse).
Therefore, the length of a year on Saturn is approximately 29.5 Earth years.
So if you want to feel a lot younger and be a child again, define your age in Saturn years instead of Earth years!
22. How long is it until our solar system ceases to exist?
It is thought that the sun is approaching roughly the halfway point of its life.
In addition, the solar system - the system of the sun - lives and dies with its star, at least in turns of being active, because it is the heat and energy from the sun that sustains the reactions on the planets that are within the reach of its light and gravitational force.
The sun has several billion years to go yet until it cools and expands, so we are no immediate danger from the sun - in fact, we can guarantee that by the time the sun is big enough, nothing we recognize as human will exist.
23. How many black holes are there?
We do not know for sure, 100%, that there are any black holes. However, beyond reasonable doubt, when the compact object in an X-ray binary system is shown to be more massive than about 3 times the mass of the Sun, then this compact object is a black hole.
With regard how many there are in total, it is thought that many, perhaps most; galaxies contain a massive black hole in their centers. If this is the case, then there will be almost as many black holes as galaxies - a great number!
24. How many earths can fit into Jupiter s great red spot?
The great red spot is a storm on Jupiter that has been raging for around 300 years or so - that is when it was first spotted.
That is quite a storm really is not it, and we do not know when it will die out. It is also rather large as the question implies.
The answer is that it is estimated something in the region of two earths would fit into the great red spot alone, which gives some idea of the colossal scale of the gas giant that is Jupiter in comparison to the smaller ball of rock that is planet Earth.
25. How many moons do Ceres have?
Ceres is a big asteroid that has just become a wannabe planet in the new solar system, unbelievably, or at least is a pluton.
26. How many moons does Jupiter have?
This is difficult to call. The stable figure for several years was 16. However, recently another 23 or so moons have been discovered and are currently being classified.
As we study the planet more and more, and with more sophisticated technology, more and smaller objects are noted. Whether these count as moons or just clumps of rock caught in orbit by the planet is highly debatable. The total count of moons for Jupiter, as at May 2005, was a staggering 63!
27. How many moons do Mars have?
With all the focus on the red planet and life, and the supposed channels that were the sign of extra terrestrial life in previous centuries, people forget about the moons of this neighbor planet, the Red Planet.
However, Mars has two moons.
These are called Phobos and Deimos respectively, and are minor satellites, so called. They are small compared to the Earth's moon, which is much larger and more significant.
28. How many moons does Neptune have?
Neptune is the planet with the fourth most moons in the solar system. The planet has 13 moons.
The planets with more moons are Jupiter, Saturn, and Uranus, in descending order of number of moons.
29. How many moons does Saturn have?
Saturn has 46 known moons (as of 4th May 2005 when 12 more were discovered).
These moons vary in size greatly, from the largest moon Titan (bigger than Mercury and Pluto), to other more controversial moons which are really just large rocks. Of the 12 most recently discovered, some are only 3 - 7 km wide, and take around 2 years to orbit the planet.
The number of moons is not stable, and more moons are being discovered all the time as detection techniques become more sophisticated.
Saturn is the planet with the second largest number of moons, with Jupiter catalogued as having the most.
30. How many moons does Uranus have?
Uranus has 27 moons. This means it has more moons than any other planet in the solar system, apart from Jupiter and Saturn.
However, it has more than twice the number of moons of the next planet in the list - Neptune.
31. How many planets are in the new solar system?
At the time of writing the new solar system has not been agreed officially, however it appears that there will be 12 planets in the new solar system, having gone up from 9 previously.
The new additions would be Ceres, Charon and an obscurely named object far away from the sun called 2003 UB319 - really needs to have a catchier name assigned to it!
32. How many planets are now in the solar system?
There are now eight planets in the solar system, as Pluto has been demoted to a planetoid along with its moon Charon that has been promoted to that status along with the largest asteroid called Ceres.
33. How many stars are there in the whole universe?
No one knows the absolute answer to this very interesting question, but many would love to know what the answer is!
We can at the least say the number is so huge that we cannot comprehend it; given that there are billions of stars in each galaxy and there may be for all we know trillions of galaxies then the number is truly collosal.
It is also of course in a constant state of flux as stars are born and other stars die or collide and change state - therefore the number is also ever changing.
34. How old is our earth?
Of course, no one knows exactly how old the earth is, however science can give what it believes to be accurate estimates of the age of the earth using various dating techniques.
At present, the generally accepted estimate is that the Earth is between some D.5 to D.6 billion years old. This is based partly on radiometric dating techniques and partly on extrapolation back in time and looking at the universe around us.
35. How old is this universe?
The answers have varied from time to time - until very recently it was thought the universe was about 5,000 years old.
The age of the earth soon put paid to that and recently sophisticated scientific techniques have pointed at a much greater age.
Some have thought the question incoherent - or at least that its presupposition should be stated clearly - that is, that the universe has a beginning and therefore point where it came into existence.
However, there seems to be strong evidence that the universe has not always existed and therefore this is a coherent question.
We need to say that if the big bang is true, we can go back only to say something like 'when was the big bang' as direct access to existence of the universe before then may be something we can never empirically have - depending on the definition of the big bang and what may have gone before.
Typical estimates of the age of the universe are around 14 - 18 billion years, based on globular clusters.
36. How was the moon formed?
How the moon formed is a good question. Over time, the theories have abounded as to how the moon was formed, and what it consists of.
The current theory that seems to fit the facts the best is that it is actually very old earth rocks. At some stage a huge collision took a massive chunk of rock out of the earth and flung it out into space - this rock became the moon.
If a human was to float in space and he look up would there be other planets on top of the planets in out galaxy. He would not be able to see the other planets without a telescope from space either, or at least not in any detail.
37. If gravity only attracts mass and if light does not have mass why does it appear to bend when passing a planet?
Under general relativity, it is seen that gravity can literally warp space-time around it.
Therefore, anything that passes through the gravitational warping will itself be influenced.
Around a massive object like the sun, there is a slight warping of space-time, and therefore everything that passes through that is affected.
This is what causes the slight bending, you notice in light waves even though they cannot have mass in the standard model (as it takes infinite energy to accelerate anything that has mass to light speed)
38. Is Pluto really a planet?
Interesting question - many have asked in recent years whether Pluto is a real planet or not.
The motivation for this has been the increased understanding of our solar system and the huge number of large rocks that have been found at a greater distance from the Sun than Pluto, which orbits it; in fact some larger than Pluto has or of similar size have been found.
This has led to many calling for our understanding of a true planet to change or for Pluto to become a planetessimal or some other non-planetary body.
However due to convention over the years and its status it seems set for Pluto to stay, however it is worth noting that there are many similar sized objects probably also orbiting the sun at a much greater distance in the Kuiper belt.
39. Is the gravitational pull on an object equalized if the object is at the centre of a planet, i.e. surrounded by the mass of the planet, which is creating the gravity?
The gravitational pull in this instance would be the same from all directions, so the net effect would be no movement.
Of course, you would have to be completely encircled by the massive objects like in the centre of a ring for instance.
40. Is the Moon escaping the earth?
The answer seems to be yes, the moon is gradually escaping from the earth's gravitational pull.
However, it is possible that this will reach a steady state, when the pull of the moon is less on the earth it will slow down or stop the rate at which the earth is slowing down its spin from the friction caused. This in turn will place a greater pull back on the moon and hence it may reach a steady distance from the earth.
41. Is there water in moon rock?
No! The tests on moon rock that has either reached earth, from meteorites or from rock brought back by astronauts, have brought a new meaning to the word dry!
Any water there was would have escaped long, long ago. This has affected the number of minerals possible on the moon - around 100 compared to the thousands on earth where water has enabled much more complexity.
42. What are asteroids like?
Asteroids have several general features of interest.
1) Firstly, their formation - they all represent material that was not used in the initial formation of the solar system.
2) For whatever reason - chance and position - they did not form planets, and therefore were left scattered.
3) They do not represent much material - it is thought that if they were all joined together the mass would only be that of half of our Moon!
4) Most asteroids are in a 'belt' between Mars and Jupiter.
5) Some asteroids even have their own mini moons - for instance Ida and Dactyl.
43. What are gamma ray bursts?
Gamma ray bursts are one of the current mysteries that are still to be explained.
If we could see gamma ray wavelengths, we would see the sky glow - and much of this is from known sources like pulsars, quasars and so on. However, from time to time we have directly observed sudden pulses of gamma rays for a few seconds at a time.
These pulses pour out massive energy. The mystery is with regard the source of these gamma rays.
44. A solar eclipse can only occur at a:
A. full moon
B. new moon
C. ½ gibbous moon
D. ¼ gibbous moon
Answer: B
45. Which of the following constellations cannot be seen in the summer sky of the northern hemisphere?
A. Libra
B. Orion
C. Ursa Major
D. Cygnus
Answer: B
46. What percent of stars in the sky that appear to be single stars are actually binary stars:
A. about 90%
B. about 50%
C. about 20 %
D. about .5%
Answer: B
47. The apparent speed of the Sun along the ecliptic:
A. is constant
B. varies during the solar year
C. varies only during winter
D. varies only during summer
Answer: A
48. In the Australian winter night sky, which of the following is true regarding the constellation Orion:
A. it is seen in the western sky
B. it is seen in the southern sky
C. it is seen in the northern sky
D. it can never be seen
Answer: C
49. The 29 ½ days it takes the Moon to complete an orbit around the Earth is called a:
A. synodic month
B. sidereal month
C. orbital month
D. solar month
Answer: A
50. Which of the following is NOT true about meteorites:
A. most of the meteorites that have been found have a high iron content
B. iron meteorites often contain 10 – 20% nickel
C. most of the iron meteorites are octahedrites
D. on rare occasions, acid-etched iron meteorites display a pattern called the Widmanstatten pattern
Answer: D
51. According to Keplers Third Law, plotting the squares of the periods of the planet against the cubes of the semi- major axes of their orbits will result in what sort of graph:
A. a parabolic line
B. a straight line
C. an irregular jagged line
D. a hyperbolic line
Answer: B
52. The time between two successive meridian transits of the Sun as observed from a stationary spot on the Earth’s surface is called:
A. the stellar day
B. an apparent solar day
C. lunar day
D. an apparent solar month
Answer: B
53. The hydrogen envelope that surrounds the comets nucleus derives its hydrogen most directly from:
A. gases escaping from the melting comet’s ice
B. hydrogen captured from interstellar space
C. breakdown of water by ultraviolet light
D. hydrogen in the solar winds
Answer: C
54. At a location half-way from the Equator to the North Pole, which of the following correctly describes the stars apparent motion:
A. they move in circles parallel with the horizon
B. they rise and set vertically
C. they remain stationary
D. they rise and set at an angle to the horizon
Answer: D
55. Light from distant galaxies comes mostly from which of the following:
A. low mass stars
B. high mass stars
C. ionized hydrogen nebula
D. large globular clusters of stars
Answer: B
56. Which of the following is NOT a superior planet:
A. Jupiter
B. Venus
C. Mars
D. Pluto
Answer: B
57. Which of the following planets has the highest escape velocity:
A. Saturn
B. Uranus
C. Jupiter
D. Mars
Answer: C
58. What is the term for the amount of energy released from each square meter of an objects surface each second:
A. energy flux
B. Pascal’s Law
C. Boltzman’s Equation
D. Kelvin’s Law
Answer: A
59. Astronomers usually detect the electromagnetic emissions of a single neutron star in what single form:
A. cosmic radiation
B. microwaves
C. radio waves
D. infrared waves
Answer: C
60. An emission or bright line spectrum consists of:
A. a series of bright lines superimposed on a black or continuous background.
B. a series of bright and dark lines superimposed on a black-lined grid
C. a series of faint black lines superimposed on a bright background
D. a circular array of dark ring patterns on a bright background
Answer: A
61. Maria on the moon are:
A. darker and smoother parts of the moon’s surface
B. mountains of the moon
C. irregular craters
D. highland areas which show up as irregular contours
Answer: A
62. Which of the following is NOT another name for the Pleiades?
A. M45
B. the seven sisters
C. the false dipper
D. the bull’s bowl
Answer: D
63. Which of the following is a pulsating variable star whose brightness varies in a very regular time period of about 1-50 days:
A. Lyrae star
B. Cepheid
C. Mira star
D. Cannon Star
Answer: B
64. Name the part of the Sun that we can see without any instruments:
The Photosphere
65. All of Saturns moons are composed predominantly of what substance?
Ice
66. Rounded off to the nearest trillion, how many miles is in a light year?
6
67. Of the three types of meteorites, which is the most common, in terms of the number of samples, to fall to Earth in recorded history:
Stony Meteorites
68. What are the scientific names for the two regions of a sunspot?
Umbra And Penumbra
69. The Kappa Cygnids and the Northern Delta Aquarids are names for what phenomena?
Meteor Showers
70. What substance is responsible for Neptunes blue-green color?
Methane Gas
71. Give the common name for the phenomenon which is the result of sunlight reflecting off the Earth and faintly illuminating the darkened portion of the moon:
Earthshine
72. Whos book, titled Concerning the Revolutions of Celestial Spheres, is considered to mark the birth of modern astronomy?
Copernicus
73. The celestial coordinate analogous to latitude is called:
Declination
74. What do Astronomers call the point in the sky that is directly overhead?
Zenith
75. A meteor that reaches the surface of the Earth is more accurately called a:
meteorite
76. Which planet in our solar system has the most circular orbit?
venus
77. Mars has a thin atmosphere composed mainly of what gas?
carbon dioxide
78. Which moon is the only other body in our solar system, besides the Earth, that has an atmosphere of mostly nitrogen?
titan
79. When a superior planet is at quadrature in reference to the Earth, what is its elongation in degrees?
90o
80. What moon of Neptune orbits in a retrograde direction?
Triton
Astronomy Multiple Choice Questions and Answers PDF Experienced Freshers
1. How far away from earth, is space?
In fact, space is said to begin just 100km above the surface of the earth so if you were in a rocket then you would not need to travel for too long to hit space.
When you look in the sky to the moon for instance you actually only need to travel a tiny, tiny fraction of the way to the moon to enter space.
2. How does gravity affect life on Pluto?
Well, there is much less gravity no Pluto than there is on the planet Earth.
Therefore, it is easier to jump for instance a jump would take you much higher. Your body would also not need the robustness that it needs to deal with gravity here pushing down on your organs and so on, so might need to be less sturdy.
3. How do clouds form?
Clouds are formed as part of the water cycle. Effectively, warm air rises. Indeed, water vapor rises, as it is lighter than air.
However, as it rises through the sky, higher and higher up, the air is colder.
This causes the water vapor to condense and it turns to liquid droplets. This is what causes a cloud to form and condense.
When the density is high enough, the water escapes from the cloud and falls to earth as a cloud.
4. How did the moon form?
Theories abound. The most widely accepted thought at present is that some massive impact on earth in its very formative days was so violent that it sent a chunk of earth rock flying out into space, and this became the moon. Certainly if true, this was very fortuitous for life on earth in the end, as the moon has many effects on the earth that are beneficial for life, e.g. tides.
5. How can space expand faster than the speed of light?
Although nothing can travel faster than the speed of light, when space is expanding itself then things can move further than light does in a period - this is because it is not a particle that is traveling it is the fabric of space itself.
Space can expand at a rate that has not been determined but will not expanded to be bound by the movement of light or particles, so if the fabric of space itself expands then things can effectively be moved apart from each other at faster than light speed without themselves exceeding the limit.
6. How big is Venus?
In terms of size, Venus is the most like Earth, although not in terms of planetary conditions, climate, or hospitability for life.
Venus is 95% the size of earth. In terms of the density of the planet, it is very close to earth. It is 30% closer to the Sun than the earth is. It is also incredibly hot - around 880 degrees Fahrenheit at times, and sulphuric acid rain. The planet has a runaway greenhouse effect problem.
7. How big is the universe?
There is an edge to what we are able to see in the universe. The most distant galaxies we can now see are 10 or 12 billion light-years away. We could never see a galaxy that is farther away in light travel time than the universe is old, e.g. estimated 14 billion years. Thus, we are surrounded by a "horizon" that we cannot look beyond that. This horizon describes the visible universe—a region some 28 billion light years in diameter.
8. Does time stop at an event horizon?
You may have read that as you approach the event horizon of a black hole, time will stop for you.
Indeed, for any observers, it will appear that you go slower and slower and never quite reach it (ignoring the problems that you would be crushed to death by the gravity!)
However, if your watch were still to work, you would look down and perceive time to be passing as normal.
It is due to the immense gravity that the light you emit takes longer and longer to reach the external observer.
9. Does non-carbon based life exist somewhere in the universe?
No one can say no in answer to this, because we do not know what else is out there.
However, it seems likely that due to its chemical properties that life elsewhere would need to be based on carbon if it was of any size, although we cannot say for sure.
There are not that many elements that seem to have the flexibility that carbon does, the stability and abundance... however it is possible that something like silicon could perhaps be a candidate for life forms elsewhere; for very simple life forms there might be a larger range of candidate elements.
10. Do galaxies interact?
Of course we have no direct evidence of galaxies interacting but it does appear that they can and do, and are at this very moment, interacting.
Usually a violent and energetic affair, galaxies interacting will cause much destruction of existing material and then result in a product phase of much star formation and activity as the repercussions are felt throughout the galaxy.
11. Do black holes really exist?
As far as we can tell, they do exist, yes. Whilst no one has directly seen a black hole, they are of course dark objects so light cannot be seen; the effects of them can be seen.
Specifically the massive gravitational field and its impact can be observed at the centre of galaxies where the orbits of stars and matter do all sorts of crazy things from the intense gravitational pulls, so objects that behave consistently with the behavior of black holes at the centre of galaxies have had their predictions confirmed, yes.
12. Did water come from comets?
One interesting theory is that most of the water came to earth from comets.
The idea is that loads of small comets, about the size of small houses, come into the atmosphere every day.
They vaporize in the atmosphere, leaving their water behind.
The idea is that 10 of these very minute for billions of years over the course of the history of the planet would lead to virtually all the water in the oceans and atmosphere!
This would be significant, as it would give an alternative explanation for the standard idea that the water came from gaseous emissions from the crust of the Earth in the early days post its initial formation...
13. Describe the Venus atmosphere.
Venus has a very strange atmosphere, compared with the similar sized planet next to it - Earth.
The atmosphere is virtually all carbon dioxide - in the region of 9%. The rest is mainly made up of nitrogen. There is thick cloud made of not water but acids like sulphuric acid - nasty stuff indeed.
The pressure is massive in the atmosphere of planet Venus - indeed Venus would crush us, as it is 90 times that of earth!
The temperature on Venus is also massive, around 500 Celsius - even some metals would be liquid on the surface of Venus!
14. How far from earth, is the moon?
The Mean Distance of Moon from Earth is 238,712 miles (384,400 km).
The greatest distance is 252,586 miles.
The shortest distance is 221,331 miles.
Interestingly, the Moon used to be much closer to the earth, and may have had a pivotal role in the evolution of life on the planet and the whole history of the planet before us, that led to our creation.
The implication of this is also that the Moon will not always be with us - the Earth is slowly losing its grip on the Moon and at some stage long, in the future, the Moon will actually escape Earth's gravitational pull and out of Earth's gravitational grasp.
15. How fast is the solar wind?
A very interesting questions this about the speed of the solar wind. This depends on conditions in and around the sun and how particularly active it is at the time and therefore varies greatly. It moves between around 200 to 900 kilometers per second.
16. How have some stars had time to die since the universe began?
This often confuses people that there are stars that have been through their entire life cycle yet there are many stars still forming.
Well part of the answer is that a large star burns quicker and dies quicker so might have its whole life cycle in the fraction of the time a star as if our own Sun does which is perhaps mid sized.
Therefore, it might take a billion years for a large star to go through its lifecycle and if stars started to form around a billion years after the big bang, then after 2-3 billion years stars could have burnt out, thus they could have died already.
17. How is Saturn like earth?
Saturn is like earth in the sense that it is one of the planets of the solar system.
Earth is also a planet. They also both are alike in that they go around the sun.
Also they both have moons, though earth has just one and Saturn has so many that we still don't know what they all are and more and more are being found around Saturn all of the time.
Therefore, in these ways they are similar.
18. How is Venus different to earth?
Venus is different to planet earth in quite profound ways. We focus, being alive, on the fact that Venus could surely not support life. This focuses us in on some massive differences between the two planets.
First, up, Venus rotates extremely slowly compared to earth.
It also has a magnetic field that is almost non-existent - not good for life! Of course, the temperature means it is so dry and there is hardly any water.
There is extreme pressure on the surface and temperature, and the atmosphere is very dense with a run away greenhouse effect.
19. How is Venus like Earth?
Venus is like Earth in some ways, mainly cosmetic, but very different in others.
However until we studied Venus in general it was thought to be a sister planet but the reality is very different. In terms of similarities are the two main facts:
1) It is the closest to Earth in the solar system, very close indeed in planetary terms
2) The second thing is that it is a small rocky planet, of almost the same size as earth
However as you will see in the differences to Earth question I just answered, the differences between the two planets Earth and Venus are much more profound than the similarities.
20. How long is a day on Saturn?
A day on Saturn is hard to measure, however scientists now believe that the value of a day on Saturn in terms of length is around 10 hours and as such being ten hours compared to our 24 it is less hours than a day on earth.
21. How long is a year on Saturn?
Saturn is much further from the Sun than the Earth is. Therefore, for it to complete its orbit around the sun once takes much longer than for Earth due to the much wider circle it has to go around in order orbiting (well, ellipse).
Therefore, the length of a year on Saturn is approximately 29.5 Earth years.
So if you want to feel a lot younger and be a child again, define your age in Saturn years instead of Earth years!
22. How long is it until our solar system ceases to exist?
It is thought that the sun is approaching roughly the halfway point of its life.
In addition, the solar system - the system of the sun - lives and dies with its star, at least in turns of being active, because it is the heat and energy from the sun that sustains the reactions on the planets that are within the reach of its light and gravitational force.
The sun has several billion years to go yet until it cools and expands, so we are no immediate danger from the sun - in fact, we can guarantee that by the time the sun is big enough, nothing we recognize as human will exist.
23. How many black holes are there?
We do not know for sure, 100%, that there are any black holes. However, beyond reasonable doubt, when the compact object in an X-ray binary system is shown to be more massive than about 3 times the mass of the Sun, then this compact object is a black hole.
With regard how many there are in total, it is thought that many, perhaps most; galaxies contain a massive black hole in their centers. If this is the case, then there will be almost as many black holes as galaxies - a great number!
24. How many earths can fit into Jupiter s great red spot?
The great red spot is a storm on Jupiter that has been raging for around 300 years or so - that is when it was first spotted.
That is quite a storm really is not it, and we do not know when it will die out. It is also rather large as the question implies.
The answer is that it is estimated something in the region of two earths would fit into the great red spot alone, which gives some idea of the colossal scale of the gas giant that is Jupiter in comparison to the smaller ball of rock that is planet Earth.
25. How many moons do Ceres have?
Ceres is a big asteroid that has just become a wannabe planet in the new solar system, unbelievably, or at least is a pluton.
26. How many moons does Jupiter have?
This is difficult to call. The stable figure for several years was 16. However, recently another 23 or so moons have been discovered and are currently being classified.
As we study the planet more and more, and with more sophisticated technology, more and smaller objects are noted. Whether these count as moons or just clumps of rock caught in orbit by the planet is highly debatable. The total count of moons for Jupiter, as at May 2005, was a staggering 63!
27. How many moons do Mars have?
With all the focus on the red planet and life, and the supposed channels that were the sign of extra terrestrial life in previous centuries, people forget about the moons of this neighbor planet, the Red Planet.
However, Mars has two moons.
These are called Phobos and Deimos respectively, and are minor satellites, so called. They are small compared to the Earth's moon, which is much larger and more significant.
28. How many moons does Neptune have?
Neptune is the planet with the fourth most moons in the solar system. The planet has 13 moons.
The planets with more moons are Jupiter, Saturn, and Uranus, in descending order of number of moons.
29. How many moons does Saturn have?
Saturn has 46 known moons (as of 4th May 2005 when 12 more were discovered).
These moons vary in size greatly, from the largest moon Titan (bigger than Mercury and Pluto), to other more controversial moons which are really just large rocks. Of the 12 most recently discovered, some are only 3 - 7 km wide, and take around 2 years to orbit the planet.
The number of moons is not stable, and more moons are being discovered all the time as detection techniques become more sophisticated.
Saturn is the planet with the second largest number of moons, with Jupiter catalogued as having the most.
30. How many moons does Uranus have?
Uranus has 27 moons. This means it has more moons than any other planet in the solar system, apart from Jupiter and Saturn.
However, it has more than twice the number of moons of the next planet in the list - Neptune.
31. How many planets are in the new solar system?
At the time of writing the new solar system has not been agreed officially, however it appears that there will be 12 planets in the new solar system, having gone up from 9 previously.
The new additions would be Ceres, Charon and an obscurely named object far away from the sun called 2003 UB319 - really needs to have a catchier name assigned to it!
32. How many planets are now in the solar system?
There are now eight planets in the solar system, as Pluto has been demoted to a planetoid along with its moon Charon that has been promoted to that status along with the largest asteroid called Ceres.
33. How many stars are there in the whole universe?
No one knows the absolute answer to this very interesting question, but many would love to know what the answer is!
We can at the least say the number is so huge that we cannot comprehend it; given that there are billions of stars in each galaxy and there may be for all we know trillions of galaxies then the number is truly collosal.
It is also of course in a constant state of flux as stars are born and other stars die or collide and change state - therefore the number is also ever changing.
34. How old is our earth?
Of course, no one knows exactly how old the earth is, however science can give what it believes to be accurate estimates of the age of the earth using various dating techniques.
At present, the generally accepted estimate is that the Earth is between some D.5 to D.6 billion years old. This is based partly on radiometric dating techniques and partly on extrapolation back in time and looking at the universe around us.
35. How old is this universe?
The answers have varied from time to time - until very recently it was thought the universe was about 5,000 years old.
The age of the earth soon put paid to that and recently sophisticated scientific techniques have pointed at a much greater age.
Some have thought the question incoherent - or at least that its presupposition should be stated clearly - that is, that the universe has a beginning and therefore point where it came into existence.
However, there seems to be strong evidence that the universe has not always existed and therefore this is a coherent question.
We need to say that if the big bang is true, we can go back only to say something like 'when was the big bang' as direct access to existence of the universe before then may be something we can never empirically have - depending on the definition of the big bang and what may have gone before.
Typical estimates of the age of the universe are around 14 - 18 billion years, based on globular clusters.
36. How was the moon formed?
How the moon formed is a good question. Over time, the theories have abounded as to how the moon was formed, and what it consists of.
The current theory that seems to fit the facts the best is that it is actually very old earth rocks. At some stage a huge collision took a massive chunk of rock out of the earth and flung it out into space - this rock became the moon.
If a human was to float in space and he look up would there be other planets on top of the planets in out galaxy. He would not be able to see the other planets without a telescope from space either, or at least not in any detail.
37. If gravity only attracts mass and if light does not have mass why does it appear to bend when passing a planet?
Under general relativity, it is seen that gravity can literally warp space-time around it.
Therefore, anything that passes through the gravitational warping will itself be influenced.
Around a massive object like the sun, there is a slight warping of space-time, and therefore everything that passes through that is affected.
This is what causes the slight bending, you notice in light waves even though they cannot have mass in the standard model (as it takes infinite energy to accelerate anything that has mass to light speed)
38. Is Pluto really a planet?
Interesting question - many have asked in recent years whether Pluto is a real planet or not.
The motivation for this has been the increased understanding of our solar system and the huge number of large rocks that have been found at a greater distance from the Sun than Pluto, which orbits it; in fact some larger than Pluto has or of similar size have been found.
This has led to many calling for our understanding of a true planet to change or for Pluto to become a planetessimal or some other non-planetary body.
However due to convention over the years and its status it seems set for Pluto to stay, however it is worth noting that there are many similar sized objects probably also orbiting the sun at a much greater distance in the Kuiper belt.
39. Is the gravitational pull on an object equalized if the object is at the centre of a planet, i.e. surrounded by the mass of the planet, which is creating the gravity?
The gravitational pull in this instance would be the same from all directions, so the net effect would be no movement.
Of course, you would have to be completely encircled by the massive objects like in the centre of a ring for instance.
40. Is the Moon escaping the earth?
The answer seems to be yes, the moon is gradually escaping from the earth's gravitational pull.
However, it is possible that this will reach a steady state, when the pull of the moon is less on the earth it will slow down or stop the rate at which the earth is slowing down its spin from the friction caused. This in turn will place a greater pull back on the moon and hence it may reach a steady distance from the earth.
41. Is there water in moon rock?
No! The tests on moon rock that has either reached earth, from meteorites or from rock brought back by astronauts, have brought a new meaning to the word dry!
Any water there was would have escaped long, long ago. This has affected the number of minerals possible on the moon - around 100 compared to the thousands on earth where water has enabled much more complexity.
42. What are asteroids like?
Asteroids have several general features of interest.
1) Firstly, their formation - they all represent material that was not used in the initial formation of the solar system.
2) For whatever reason - chance and position - they did not form planets, and therefore were left scattered.
3) They do not represent much material - it is thought that if they were all joined together the mass would only be that of half of our Moon!
4) Most asteroids are in a 'belt' between Mars and Jupiter.
5) Some asteroids even have their own mini moons - for instance Ida and Dactyl.
43. What are gamma ray bursts?
Gamma ray bursts are one of the current mysteries that are still to be explained.
If we could see gamma ray wavelengths, we would see the sky glow - and much of this is from known sources like pulsars, quasars and so on. However, from time to time we have directly observed sudden pulses of gamma rays for a few seconds at a time.
These pulses pour out massive energy. The mystery is with regard the source of these gamma rays.
44. A solar eclipse can only occur at a:
A. full moon
B. new moon
C. ½ gibbous moon
D. ¼ gibbous moon
Answer: B
45. Which of the following constellations cannot be seen in the summer sky of the northern hemisphere?
A. Libra
B. Orion
C. Ursa Major
D. Cygnus
Answer: B
46. What percent of stars in the sky that appear to be single stars are actually binary stars:
A. about 90%
B. about 50%
C. about 20 %
D. about .5%
Answer: B
47. The apparent speed of the Sun along the ecliptic:
A. is constant
B. varies during the solar year
C. varies only during winter
D. varies only during summer
Answer: A
48. In the Australian winter night sky, which of the following is true regarding the constellation Orion:
A. it is seen in the western sky
B. it is seen in the southern sky
C. it is seen in the northern sky
D. it can never be seen
Answer: C
49. The 29 ½ days it takes the Moon to complete an orbit around the Earth is called a:
A. synodic month
B. sidereal month
C. orbital month
D. solar month
Answer: A
50. Which of the following is NOT true about meteorites:
A. most of the meteorites that have been found have a high iron content
B. iron meteorites often contain 10 – 20% nickel
C. most of the iron meteorites are octahedrites
D. on rare occasions, acid-etched iron meteorites display a pattern called the Widmanstatten pattern
Answer: D
51. According to Keplers Third Law, plotting the squares of the periods of the planet against the cubes of the semi- major axes of their orbits will result in what sort of graph:
A. a parabolic line
B. a straight line
C. an irregular jagged line
D. a hyperbolic line
Answer: B
52. The time between two successive meridian transits of the Sun as observed from a stationary spot on the Earth’s surface is called:
A. the stellar day
B. an apparent solar day
C. lunar day
D. an apparent solar month
Answer: B
53. The hydrogen envelope that surrounds the comets nucleus derives its hydrogen most directly from:
A. gases escaping from the melting comet’s ice
B. hydrogen captured from interstellar space
C. breakdown of water by ultraviolet light
D. hydrogen in the solar winds
Answer: C
54. At a location half-way from the Equator to the North Pole, which of the following correctly describes the stars apparent motion:
A. they move in circles parallel with the horizon
B. they rise and set vertically
C. they remain stationary
D. they rise and set at an angle to the horizon
Answer: D
55. Light from distant galaxies comes mostly from which of the following:
A. low mass stars
B. high mass stars
C. ionized hydrogen nebula
D. large globular clusters of stars
Answer: B
56. Which of the following is NOT a superior planet:
A. Jupiter
B. Venus
C. Mars
D. Pluto
Answer: B
57. Which of the following planets has the highest escape velocity:
A. Saturn
B. Uranus
C. Jupiter
D. Mars
Answer: C
58. What is the term for the amount of energy released from each square meter of an objects surface each second:
A. energy flux
B. Pascal’s Law
C. Boltzman’s Equation
D. Kelvin’s Law
Answer: A
59. Astronomers usually detect the electromagnetic emissions of a single neutron star in what single form:
A. cosmic radiation
B. microwaves
C. radio waves
D. infrared waves
Answer: C
60. An emission or bright line spectrum consists of:
A. a series of bright lines superimposed on a black or continuous background.
B. a series of bright and dark lines superimposed on a black-lined grid
C. a series of faint black lines superimposed on a bright background
D. a circular array of dark ring patterns on a bright background
Answer: A
61. Maria on the moon are:
A. darker and smoother parts of the moon’s surface
B. mountains of the moon
C. irregular craters
D. highland areas which show up as irregular contours
Answer: A
62. Which of the following is NOT another name for the Pleiades?
A. M45
B. the seven sisters
C. the false dipper
D. the bull’s bowl
Answer: D
63. Which of the following is a pulsating variable star whose brightness varies in a very regular time period of about 1-50 days:
A. Lyrae star
B. Cepheid
C. Mira star
D. Cannon Star
Answer: B
64. Name the part of the Sun that we can see without any instruments:
The Photosphere
65. All of Saturns moons are composed predominantly of what substance?
Ice
66. Rounded off to the nearest trillion, how many miles is in a light year?
6
67. Of the three types of meteorites, which is the most common, in terms of the number of samples, to fall to Earth in recorded history:
Stony Meteorites
68. What are the scientific names for the two regions of a sunspot?
Umbra And Penumbra
69. The Kappa Cygnids and the Northern Delta Aquarids are names for what phenomena?
Meteor Showers
70. What substance is responsible for Neptunes blue-green color?
Methane Gas
71. Give the common name for the phenomenon which is the result of sunlight reflecting off the Earth and faintly illuminating the darkened portion of the moon:
Earthshine
72. Whos book, titled Concerning the Revolutions of Celestial Spheres, is considered to mark the birth of modern astronomy?
Copernicus
73. The celestial coordinate analogous to latitude is called:
Declination
74. What do Astronomers call the point in the sky that is directly overhead?
Zenith
75. A meteor that reaches the surface of the Earth is more accurately called a:
meteorite
76. Which planet in our solar system has the most circular orbit?
venus
77. Mars has a thin atmosphere composed mainly of what gas?
carbon dioxide
78. Which moon is the only other body in our solar system, besides the Earth, that has an atmosphere of mostly nitrogen?
titan
79. When a superior planet is at quadrature in reference to the Earth, what is its elongation in degrees?
90o
80. What moon of Neptune orbits in a retrograde direction?
Triton
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