ASK ANTON

Previous Questions

Theresa Stickland asks:
Could you please tell me the proper name for our galaxy and solar system?

The Proper name for our galaxy is simply 'The Galaxy' (with a capital 'G'), as opposed to other galaxies (small 'g'). You may have heard it referred to as the Milky Way, but to be totally correct this is simply the name for the band of light we see in the night sky during summer, autumn and early winter. The Milky Way is just the visible part of our Galaxy. However, books do mix them up, not surprisingly. Our solar system doesn't have another name unfortunately. Maybe we could make one up! Sol is the Greek name for our Sun, so Solar System means the System belonging to Sol - easy.

Paul Robinson (age 14) asks:
Why are there so many craters on the Moon but so few here on Earth?

The Earth and moon were bombarded by the same amount of asteroids and rocks during the early ages of the solar system. However, the difference in the number of craters lies in the fact that the Earth has an atmosphere and the Moon doesn't. What an atmosphere does is wear away all the craters with rain, wind, heating and freezing, etc. The oceans also erode them away, and we have plate techtonics dpong their bit too. The Moon, having no atmosphere, has nothing to remove the craters, so there they have stayed, some for over 3 billion years.

Loti Chola from Luanshya in Zambia wonders:
What would hAppen to the Earth if we had no Moon?

The MOON gives us the main part of our tides. The Sun's pull on the water is about half that, so take the Moon away and there would be less of a swing from high to low tides. We would have no eclipses. The recent lunar eclipse and last year's spectacular total eclipse of the Sun would simply not have existed, or there wouldn't be any more of them, depending on when you took or are planning to take the Moon away. Of course the Moon is actually moving away from us! No need to panic however, it's only about 4cm per year. It's all to do with the tides slowing the Earth down, minutely, and the energy is transferred to the moon. Over millions of years it will move further away, but it'll never gain enough energy to leave orbit you'll be glad to hear.

Gareth Cleaver asks:
Please can you tell me if Charon is a planet or a moon?

Charon is the only moon of the planet Pluto. That's not to be confused with Chiron, which is an asteroid.

Charles Wompiah from Obusi, Ghana asks:
Do stars live for ever?

No. Stars are simply great balls of gas, mainly hydrogen, which they use as fuel. In the centres of stars hydrogen is being fused under intense pressures and temperatures to form helium. As it does, lots of heat and light is made, and this radiation also holds up the star. The pressure from these reactions stops the star from collapsing under the immense force of gravity. Sooner or later, depending on how massive the star is, this fuel will be used up, the star changes, collapses, explodes - there are many different endings for stars. But they will all end. Some will even become mysterious Black Holes.

Kasia Thompson (age 13) asks:
How is a star born?

Stars are born from huge clouds of dust and gas called NEBULAE. Clumps of material start pulling themselves together under gravity (the same force that holds you down on the ground) until the heat and pressure are high enough for nuclear reactions to start, and a star is born.

Daniel Allcock (age 9) asks:
How far can the Hubble telescope see?

Because Hubble is outside the Earth's atmosphere it has an incredibly clear view deep into space. In fact one area of study is called the Hubble Deep Field. Within this small area over 1,500 galaxies have been seen, many for the first time. The distance to some of these galaxies hold the answer to your question: they are around 14 billion light-years away! This means it has taken light 14 billion years to travel the Universe from these distant galaxies to Earth. Seeing as the Universe is probably 15 billion years old, there's not much more 'time' left for Hubble to look back at.

Bennifrid Savlon from Budapest, Hungary wants to know:
What is a supernova?

A supernova is a massive explosion in space which can sometimes be seen here on the Earth. It looks like a very bright star has suddenly appeared, and may outshine everything else in the night sky. Occasionally this new star can even be seen during the day! There are two causes for supernova explosions. One is due to a massive star coming to the end of its life. All the nuclear reactions that keep the star shining and hot begin to stop as the 'fuel' runs out. All these reactions also keep the star's core from collapsing down under gravity. No reactions and gravity takes over. The core smashing down, the particles colliding to form possibly a dense neutron star, or even a black hole. Meanwhile a shockwave from this collapse is sent through the outer layers of the star, heating them and blasting them out into space. The other cause for a supernova happens in a system of two stars orbiting each other. One of the stars is a dense white dwarf with a tremendous amount of gravitational pull which draws away the gas from the other star. This gas builds up and up and up until it explodes. Easy. We haven't seen any bright supernova in our skies for a long time. If we look at the records, the Chinese observed one in Taurus in 1054, the famous astronomer Tycho Brahe saw one in Cassiopeia in 1572, and the last naked-eye supernova was viewed by another great astronomer and mathematician Johannes Kepler in Ophiuchus in 1604.

Rajendra Potavadoo from Vacoas, Mauritius asks:
Why do stars shine with different colours? Some are blue, red, yellow and others appear white.

Those of you who have only ever just glanced up at the sky may think all the stars are the same colour, namely white. However, as Rajendra points out they can be many colours. The fact that the colours are so difficult to see are due to the low light levels of the stars, and the effect this light has on your eyes. We have rods and cones in our eyes - the cones detect the colour, but only when it's bright enough, while the rods see black and white, and these can work to quite low levels of light. So stars of pretty colours that are faint are seen as white by your eyes, because your cones have already switched off. So, we only see the brighter stars with any colour, and this brings us onto the reason for the colour: it's simply to do with the surface temperature of the star. The hottest stars are blue, then cooling slightly we have white stars, then yellow (like our Sun), orange, and finally red, which are the coolest stars. So, next time you're gazing starward, have a look for any colours.

Mohammed Abdul Ganiyu from Takoradi, Ghana wants to know:
What is a Sun Quake, how devastating is it and where in the world has it occurred?

This might surprise some readers, but actually Sun Quakes don't occur on the Earth, they happen on the Sun! It was in May 98 that scientists showed that solar flares produce seismic waves in the Sun's interior that resemble those created by earthquakes. And they are powerful: the Sun quake observed contained about 40,000 times the energy released by the 1906 earthquake that devastated San Francisco. Although a moderate flare, it released an immense amount of energy, equal to completely covering the Earth's continents with a 1 metre of dynamite and detonating it. The quake looked much like ripples spreading from a rock dropped into a pool of water. But over an hour, the solar waves travelled a distance equal to 10 Earth diameters before fading away. Also, unlike water ripples that travel a constant velocity, the solar waves speeded up.

Yorgie Petersen from the United States of America asks:
What would happen if the Earth stopped spinning?

Firstly let me reassure everyone that the Earth will never stop. It will be boiled off into space by the expanding Sun long before that could ever happen. But let's just pretend: Those on the side facing away from the Sun would freeze, those facing the Sun would boil. The atmosphere would be thrown into turmoil, the correolis effect no longer would cause the predicted movement of the cyclones and the oceans. Nocturnal animals would be confused wherever they were. If you lived on the dayside you would always be at work, and always asleep on the dark side. This is because time would be fixed - the earth isn't spinning. You may live forever at 10.30am. Unable to leave school or work forever.

Mohammad Hassan from Pakistan writes:
I heard of a 10th planet in our solar system called 'Vulcan', that appeared and then disappeared - What happened?