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Ask the Experts - Astronomy and Astrophysics
What 2 constellations or clusters of stars can we see all year long?
Is the earth's rotation slowing down?
If Big Bang theory suggests that the universe started out as a homogeneous mass that spread uniformly in all directions, how did we get 'lumps' [stars, galaxies, etc] in the universe?
Currently,where are the Voyagers 1 and 2 space probes?
If an orbiting artificial satellite were to slow down, what would happen?
What are the upper and lower limits for the mass of a neutron star? - and why?
If nothing can come out of the black hole, how come the x-rays can be emitted?
What is the difference between black hole singularity and big bang singularity?
We know that fire needs oxygen in order to burn. Then how come stars continue to burn even though there is no oxygen in space?
What is the minimum altitude from the equator needed to view the Earth as a whole?
How do we know that the light from a distant, moving source has shifted from one part of the spectrum to another?
If most of the large galaxies have black holes at the center, why do photos show a very bright spot instead of a black spot?
Why is it that the lunar disk precisely covers the solar disk during a solar eclipse? Is it just an extraordinary coincidence?
How can one measure the age of the universe?
Would Jupiter float in a body of water?
If you lived on the Moon, would you see the sun rise and set? how about the earth?
Could someone please explain to me the difference between a Type 1 Nova, and a Supernova?
How astronomers know that our galaxy is not centre of universe?
What are Kepler's laws of motion and what exactly do they mean?
Why is Pluto so different from the other planets?
How long did radio commands take to travel from the Earth to Voyager as it passed Neptune?
How did the earth come to have a molten iron core?
What is the hottest part of the Sun?
How come x-rays can escape from a black hole when visible light can not?
Is there really a planet X?
What is the method used to find out the distance of Andromeda galaxy from us?
Why do most of the planets orbit the sun fairly on the same plane?
Why is it dangerous to look at the solar eclipse directly specially at that moment?
Why are all stars yellow?
I was taught in school that the Sun DOES NOT MOVE at all. But it does move around the galaxy at the speed at 250km/s. And does it spin? Please give me a bigger picture to look at.
Would it be possible to see the rings of Saturn with a telescope? How can one find out what years the rings are visible?
What is the Andromeda Galaxy distance from the Sun?
How many miles does the Earth travel in space each day?
Has anyone ever calculated how far we are from the point of the big bang?
Names of stars usually start with letters NC and are followed by numbers. What does NC stand for and why are they named as such?
Why does the night-sky in spite of the presence of countless stars appear dark?
How are quasars related to black holes?
What are the differences between jet airplanes and rockets?
What is meant by background radiation?
Why does space shuttle fly up with its belly upward and its back downward (i.e., astronauts sitting upside down)?
If a spacecraft was fitted with a laser would the photons emitted push the craft upwards as in the solar sail or beamed energy propulsion concepts?
Is there a day and night on the moon?
Is it possible to place a satellite in geostationary orbit over the north pole?
At what point does a black hole stop sucking in mass and explode creating a new time/space continuum?
How were pulsars discovered?
Will the earth's orbit around the sun eventually decay as a satellites orbit decays around earth orbit?
How many astronomical units are in a light year?
What would happen if Earth lost it's tilt and just stood vertical?
What happens to the charged particles which came from the sun after they hit the atmosphere of the earth?
Why does the north star always point north?
Do all galaxies have black holes at their centers? If not, what provides the gravity to hold the galaxy together?
If there is no gravity in space, how do astronauts digest their food?
Is it true that the further a planet is from the Sun, the faster it rotates around itself?
What is meant by the theory that the sun is a third generation star?
Discounting mountains, valleys, and other gross surface features, is there any place on Earth from which the Moon is not visible at all?
Why do asteroids leave the asteroid belt in the first place?
How much math is needed to become an Astronomer? What kinds of math must you know?
If a planet was at a distance of 3.6 parsecs, how many light years away is this planet?
How do diffraction gratings tell us information about distant stars and galaxies?
What will be the fate of our moon? Will it remain in a stable orbit, crash back into Earth or drift off into space?
Why is Venus the hottest planet even though Mercury is closer to the sun?
Does the sun move at all?
Where does the dark energy / matter come from?
Are there any galaxies that have a blue-shift?
Where are the Pioneer and Voyager space probes? Are they still operating? Is anybody listening to them?
Does gravity have a speed?
How did planet Neptune get its name?
Can you hit a golfball into orbit on the moon?
If the size of the universe is infinite and the speed of light is constant, are there places light has not reached?
Why are there no stars when the astronauts take pictures from space?
If neutrinos have mass, as my physicist nephew from Fermilab says is now the consensus, how can one explain the virtual simultaneous arrival of neutrinos and photons from the Supernove1987A in a Magellanic cloud about 300,000 light years away?
Why the planets are not twinkling, while the stars are?
What is the basic difference between Astrophysics and Astronomy?
Which planet rotates so fast that its day is only 10 hours long?
What is a quasar and what does it have to do with a black hole?
Which of these 3 sports will be the hardest or the easiest to play on the moon? Basketball, Soccer or Football?
What is the ultimate fate of our sun?
How are solar sails possible? If photons have no mass, how can they push on something?
When matter is dragged into a black hole, where does it go or what happens to it?
The Second Law of Thermodynamics states that the universe tends toward high entropy. If so, what happens when there is nothing left to be disordered? How can matter be constant?
What is the angular velocity of the Earth around the Sun? How do we get it?
How long does it take for moonlight to reach the earth?
What is cosmic radiation? Is it dangerous?
How does a star become a supernova or a black hole? How does the star decide which one to turn into?
How was the critical density of the universe calculated?
What is singularity and why do all laws of physics break down at singularity?
The Nasa newsletters state sun spot activity is increasing from expected count. What is the cause for excessive sun spot activity?
Now that the universe is proven flat, what implications does it have on the special theory of relativity, particularly the gravitational aspect?
How can I prove that the earth rotates around the sun?
What is the speed of light in parsecs per year? What is a parsec?
What is the Astronomical Unit?
Is there any experimental data supporting the existence of gravitons? If there is, how fast do these wave/particles travel? Are they similar to photons?
Does the universe have a total angular momentum?
Lets just say a huge asteroid hits the earth at the right speed and with the right amount of force and stops it's orbit around the sun. How long would it take for the earth to plummet into the sun?
By what method is the size (or volume) of the universe at the moment of the big bang (or shortly thereafter) determined? Related to this, how is the size of a black hole determined?
What are we going to be able to see on may 5th. when all planet are in a line, if the clouds don't block us?
I heard that when international space station completed it could be seen by naked eye on the earth. Is this correct?
What is meant when one says that the temperature of the cosmic background radiation is 3K?
Is our moon's gravitational field strong enough to retain a gaseous envelope and is there a gas with a sufficiently high molecular weight that could be used to create an 'atmosphere' for our moon?
Could a circular space station simulate the Earth's gravity by spinning at a certain velocity? (I have seen something like this in A.C. Clarke's 2001)
I am curious as to what causes the Earth's spin, and why does the Moon not spin?
How are the rings of planets formed and what are they made out of?
When the planets in our Solar System are in a line on 5 May 2000, will there be any reason for concern on Earth?
What exactly is the heat death of the universe and where can I find out more?
How are we able to determine the composition of our orbiting planets?
If the term 'absolute motion' has no meaning, then why do we say that the earth moves around the sun and not vice versa?
Since the sun is one giant ball of gas, what force holds its consistent shape and size? Why doesn't it expand and burn up quickly?
Why does a solar eclipse move from west to east, while the sun moves from east to west?
How is the distance to the stars measured?
Someone kindly explain,please.My atoms left the spot of the 'BIG BANG' at it's ocurance some 15 billion years ago.They traveled at a relatively slow rate compared to the speed of light.therefore,would not the light generated at BIG BANG time have passed me by and been long forgotten.Yet,we get reports of light from near the time of the BIG BANG just being received as if we had been here all along awaiting it?
Given that space is expanding, why is it that it is still '3,000 miles' from New York to San Francisco? Why is it that the volume of the space in a crystal lattice of, say, NaCl, still X cubic Angstroms? Doesn't 'local' space expand too?
Would not the speed of a light beam headed toward a black hole increase tremendously? We do know it could be bent by the gravity of a star.
'The atomic bomb ... made the prospect of future war unendurable. It has led us up those last few steps to the mountain pass; and beyond there is different country.'
J. Robert Oppenheimer
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