Astronomy

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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!

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.

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.

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.

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.

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.

Ceres is a big asteroid that has just become a wannabe planet in the new solar system, unbelievably, or at least is a pluton.