Can you tell me what are comets & when will they hit earth?
NUPUR, AGE 14, MUMBAI Answer: Comets are objects that orbit the Sun much further away than Pluto. Because they are so far away there is barely any heat or light reaching them from the Sun. As a result, they freeze up. Sometimes the objects crash into each other sending one of them in toward the Sun and toward the planets. As they get closer to the Sun, the Sun heats the ice and causes it to melt which then forms the amazing tail you see in pictures. Unfortunately I do not know when one will hit the Earth. We are looking out for them but we are lucky to have the big planet Jupiter in the Solar System. Jupiter is so big that it attracts many of the comets that head are way. It works like a cosmic vacuum cleaner. 
Venus in transit across the sun |
Do other planets experience eclipses as we do here on Earth? If so, do the planets eclipse each other?
ALEXANDREA WAGNER Answer: Other planets do experience eclipses although they are not as spectacular as the solar eclipses we have here on Earth. Any planet that has a moon will experience a solar eclipse as the moon blocks sunlight from reaching the planet and a lunar eclipse as the planet blocks sunlight from reaching the moon. We do see planets eclipsing the Sun, even from Earth. Over the last 10 years there have been two events called transits where Mercury and Venus have passed between the Earth and Sun. The picture shows Venus passing in front of the disk of the Sun in 2004. Venus is the tiny black disk. On Earth there are living things. Do any of the other planets have grass/water and all those kind of stuff that support life?
ROHAN SOLANKI, AGE 10, NEW ZEALAND Answer: We have found water ice on the Moon, Mars and on comets but we have not found it as a liquid, such as rivers or seas anyway other than Earth. Some patterns on Mars make us believe that water has been running across the surface millions of years ago but not any more. Can you explain how the earth experiences different seasons?
NIKKI, AGE 12, AUSTRALIA 
Planet Earth |
Answer: As you know, the Earth spins once everyday, that gives us day and night. The axis that the Earth spins on is tilted over at an angle so itβs not quite spinning upright. When the Southern hemisphere has its summer then the Southern hemisphere is pointing toward the Sun. At the same time, the Northern hemisphere is pointing away from the Sun and so has winter. The opposite is the case six months later. Why is it difficult to leave the Earth?
DARA OBAKIN, AGE 12, SURREY Answer: It's difficult to leave the Earth because gravity keeps us pressed against the surface. To escape from the gravity of Earth, we must fly rockets at 11km per second, otherwise they will fall back to the Earth. Can you push a 10 ton block of metal in space? Since there's no gravity in space you should shouldn't you?
RYAN, AGE 12, CANADA Answer: You could easily push a 10 ton block of metal in space because neither gravity nor friction will try to stop you. However because there is no friction or gravity, however hard you push the block of metal, you will go back by the roughly the same amount. If we fell through our solar system when and how would we land?
ELLA, AGE 9, FOREST HILL, LONDON Answer: We only fall on the Earth because something called gravity pulls us down to the surface. The Sun and all the other planets in the Solar System have their own gravity but space doesn't have gravity. You would not fall through the solar system. If you flew through it in a rocket you would just go straight through into deep space. How hot is the sun?
RUTH, AGE 12, DUNEDIN, NEW ZEALAND Answer: The Sun is just like all the other stars in the sky, it's a big ball of gas. The temperature at the visible surface of the Sun is about 6,000 degrees but is much hotter in the centre at 15 million degrees. 
Black Hole |
How do we know black holes are there if light can't escape it?
AILISH, AGE 8, GLASGOW Answer: You are right that black holes are black and impossible to see, but we can see what they do on the area around them. For example we can see material glowing brightly as it is being sucked into the black hole. Are there any other planets in our solar system past Pluto? I keep getting contradictory results when I try to search for information on this.
ALEC, AGE 11 FROM MILWAUKEE, WI Answer: The reason you are getting contradictory results is that there is no real difference between a planet and an asteroid. Planets tend to be bigger than asteroids but there is no official definition. Even Pluto is sometimes called an asteroid rather than a planet. But in answer to your question, there are two other objects beyond Pluto; Sedna and Quaoar which have been suggested are planets. Both are quite small, certainly smaller than Pluto but until there is an official definition some astronomers will come them planets and others will call them asteroids. Who was the first person to discover how far the Earth is away from the Sun and how did they do it?
JASON, AGE 18 FROM NORMAN, OK Answer: The two key people who together enabled us to understood how we could measure the distance to the Sun were Edmund Halley (of comet fame) and Johannes Kepler. Halley realised that if we found accurately, the distance to Venus during one of its passes in front of the Sun that we could use that information along with Keplers laws of planetary motion to calculate the Sun's distance from the Earth. This essentially relied on no more than fairly simple trigonometry. Observations of the events were made in following years by a number of different astronomers and the value was fine tuned as the years progressed. Read more answers Β» Check out more astronomy stuff here Β»
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