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Asked by anthony848 to Jack, Jon, Tom, Yalda on 11 Mar 2013.
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Yalda Javadi answered on 11 Mar 2013:
What a great question! 🙂
For stars that are within a few hundred light years, astronomers can use ‘parallax’ to measure the star’s position from one spot from the earth’s orbit around the Sun. And measure the same position again six months later. Then with some impressive maths and trigonometry they can calculate the distance in ‘parallax seconds’. 1 parallax second = 3.3 light years!
Anything over 400 light years, astronomers can’t directly measure the distance so instead they measure the brightness of the star from its colour.
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anon answered on 11 Mar 2013:
Errrrrmmm, honestly, I have no idea. I could Google it for you, but you’ll just realise I’m copying it straight off the internet (something teachers also spot in homework!)
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Jon Marles-Wright answered on 11 Mar 2013:
I couldn’t tell you how to work it out, but know the unit is a parsec because of a long standing criticism of Star Wars Episode IV.
In it, Han Solo claims he can do the Kessel run in under 12 parsecs, but parsecs are a unit of distance, not time. Some people argue that what he meant was that he was able to plot a risky, but shorter course on the Kessel run that went very close to a black hole, so that’s why he was showing off about it.
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Tom Branson answered on 12 Mar 2013:
Yalda is right. It takes some complicated maths and a good telescope!
@Jon I think that Han Solo was maybe travelling so fast that he bent space-time… but that was a long time ago, in a galaxy far far away.
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Jack Heal answered on 14 Mar 2013:
I had to look this up too! Yalda’s answer is right. It’s called triangulation. This is where, if you know the length of one side of a triangle and the two angles pointing to the third point of the triangle then you can work out the length of the other sides.
This uses something called the “sine rule” which you might meet in maths in year 11!
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