Astronomers once wanted to know what the surface of the moon and Mars looked like. Now we've been to the moon and sent robots to Mars, so they have new and more complex problems to ponder, such as:
Are we Martians? Scientists now agree that life could survive the trip on an asteroid to Earth from Mars, and what look like microbes have been found on a meteorite. A rock from Mars hits the Earth about once a month, on average, so there was plenty of opportunity for life to have been seeded here. If we find life on Mars, and compare it to the most basic life forms here, it will help to answer the question. More questions below...
Will we be wiped out by an asteroid? One is headed our way in 2060, although there seems to be more effort to deflect it in the media (by denying that it can hit us) than by scientists who might really be able to move it into another path. Also, in the southern hemisphere (where most of these rocks come from), almost nobody is looking out for them. The asteroids themselves puzzle us. Some are solid chunks of stone or metal, while others are piles of rubble. We need to know which kind is going to hit us before we can safely bomb it into smithereens or drag it out of the way. Is there water on Mars? This will tell us whether there could have been life there in the past?or if life is there now. A big breakthrough came when ice was discovered there, but no one knows if water exists in a melted state that is conducive to life. On the other hand, life has been found in stasis in frozen parts of the Earth, meaning there may be Mars microbes in the ice that are waiting to come back to life. Dark streaks have been seen on the planet during the Martian spring that could come from running water or even a simple form of life.
Are we alone in the universe? Until we can travel far out into space, the best way to guess is to look for star systems that are similar to ours. If there are lots of them, then life is likely to be common as well. If our solar system is unique, we may be alone. One thing that has helped life to live long enough on the Earth to evolve is the presence of the giant planet Jupiter, which deflects destructive incoming asteroids. We have seen other solar systems with giant outer planets (mostly all we can see is the giant planet).
What is Dark Energy? It?s more powerful than gravity and works against it by gradually forcing everything in the universe apart. No one knows what it is or where it is, but they know it?s makes up 65% of everything in the universe. Dark matter makes up 30% of the universe, leaving us with only 5% for the matter and energy we can see. Astronomers now think that all galaxies are eventually become frozen in time or else time never ends.
What?s Up with the Milky Way? We now know there?s a black hole at the center of our galaxy, but it?s not sucking in everything around it, like most black holes do. Astronomers think that this giant hole might actually be a merger between two black holes, and that one switches off the activity of the other one.
What?s up with the Sun? We still don?t understand the star that gives us life, and why it roars into giant sunspot activity periodically (and how these spots affect us and the Earth?s future). New pictures of sunspots taken in 2002 reveal mysterious canal-like structures reaching from bright regions into the dark hearts of sunspots.
How old is the universe? Scientists have analyzed white dwarf stars to calculate the age of the universe. Most think it?s between 12 billion and 15 billion years old, but new dwarf sightings keep changing this estimate. Also, what exactly happened at the beginning of the universe, and what existed before that instant? Since no direct observations can be made of those time frames, we may never get those answers.
Does the Moon Hold Earth?s Secrets? Astronomers think rocks from Earth landed on the moon billions of years ago, due to asteroid impacts. If we could study those rocks, we?d learn a lot about the early history of Earth. We can?t find that out here at home, because the Earth continually recycles its surface material, folding it inward, where it melts and reforms. The moon doesn?t do this, so it?s a museum of planetary history. There are probably 11,000 pounds of Earth rock just under the surface of every square inch of the moon.
Did our solar system move? When scientists put our solar system into a computer, it says we have only 7 planets?Uranus and Neptune are missing. This is because our model of planet formation requires material to collide and stick together over millions of years. But out where Neptune and Uranus are, there was never enough material for this to work. Astronomer Alan Boss thinks the four big planets in our solar system did not develop from rocky cores, but collapsed from large gas and dust clouds. And he thinks this happened in another part of space, where there?s enough UV radiation to collapse Uranus and Neptune down to their current sizes. Then he thinks the solar system moved to its present location?a more pleasant area where life could evolve.
Man has been studying the stars for a very long time. The ancient Mayans were experts at it?did they discover a calamity that will befall us in 2012?
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