Wednesday 29 January 2014

Letter to a local Primary school in response to their astronomy questions...

I will try to answer all your questions in one letter, please email me if you have any future questions or tweet me @SotonAstrodome

What are black holes? How are black holes formed? Are they really black?
When a massive star, about 8 times bigger than our sun dies the star explodes, this is called a Supernova. The core that was at the centre of the star gets left behind, this core is so massive that it can’t hold itself up anymore, the massive gravity forces on it squash it down so much that it gets squashed into a very small invisible point known as a black hole. Black holes are actually more ‘invisible’ than black, but because space is black then this makes sense. They are invisible because they don’t give out light (like the Sun) or reflect it (like the Moon).

Are there any black holes in space? If so, how many are there? Is there a black hole in the Milky Way?
Yes! There are loads of black holes in our Universe; in fact there may be as much as 100 million black holes (which are each about the size of 8 suns, squashed into a very small volume) inside our own Milky way galaxy.
There is also a supermassive black hole in the center of our Milky way galaxy, which has a mass as big as 400 million suns. We know how big it is by looking at the speeds of stars moving around this invisible object at the center of our galaxy.
We don’t know the exact value for the number of black holes in our galaxy (or the Universe) because black holes are black, they don’t give out light like stars, or reflect it like planets, so we only know they are there when we can see stars orbiting the black hole, or being eaten by a nearby black hole.

Did any spaceships go into any blackholes?
No, we have not sent any spaceships to any black holes. Firstly they are all extremely far away and it would take many hundreds of years to get to the nearest black holes with the current technology. Also from using Mathematics and Physics formulas we can predict that any spaceship would get ripped apart by the strong gravity forces before it go to the black hole. Even if the spaceship was able to enter the black hole the signals it would send back to Earth, to tell us what was going on as it fell into the black hole, would also get sucked into the black hole. No information (not even light which is the fastest thing ever) can leave a black hole when it goes in. So basically, we will never known what goes on inside black holes exactly. They are very bizarre environments where our science theories fall apart, but we will keep trying to understand them.

Is there life on Mars? Is there life in the Andromeda galaxy and the rest of the Universe?
We have found water on Mars (mainly as ice or vapour) but at the moment we have not found any life, on Mars or anywhere else in the Universe. I personally believe that there IS such a thing as ‘Life on other planets’ or Aliens because from using the Kepler telescope to look at stars inside the Milky way we have found over 2,000 planets orbiting these stars.
You can actually help us find planets from this Kepler data by going on the website

Current scientific research tells us that at least 1 in 5 stars that exist, have at least one planet. And there are 100,000,000,000 stars in the Milky way and 100,000,000,000 galaxies in the Universe, so there are a lot of places for Aliens to live. The Universe is SO big I think there has to be life out there somewhere.

What planets are we most likely to find life on?
If we assume that ‘Aliens’ are like us humans then we are more likely to find them on planets like our own Earth. This means the planets should have liquid water on them, and their distance from their star (which is probably like our Sun) is in what we call the ‘Habitable Zone’ or ‘Goldilocks Zone’ where the temperature is such that water is liquid on that planet.  Although, if these ‘Aliens’ don’t need liquid water then it is quite possible they could live on any kind of planet, hot or cold and their planet could orbit a star which is nothing like our Sun.

Did any things fall on the Earth? What are the things?
Rocks from space land on Earth all the time. When the rocks fall through our atmosphere they burn up and we see them as shooting stars, these are called Meteors. When these rocks actually land on the Earth they are called Meteorites. Meteorites are usually made of stones or iron and we think most of them come from the asteroid belt between Mars and Jupiter.
A famous meteorite called ‘Alan Hills 84001’ fell to Earth in 1984 and landed in Antarctica, it came from the planet Mars. It was thought to show evidence of fossilised life from Mars inside the rock. After further investigation from the scientists it was decided that the fossils were not proof of life on Mars and possibly a result of contamination from Earth life.

What is negative energy and is it real?
I think you mean ‘Dark Energy’. This energy is very real, and is responsible for giving the Universe the energy to expand outwards at a higher rate than expected.

Is it true that in space your spine grows in length?

Yes, astronauts on the International Space Station who spend time living in microgravity have been known to grow taller in space, for example, someone 6 feet tall can grow by as much as 2 inches.

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