[todd freed]

todd freed  asked the Naked Scientists:
   
Hello Naked Scientists!

I have recently read a very interesting book about astronomy.

I have learned that one of the ways we measure the distance to distant stars is stellar parallax. With this method, you measure the stars position in the sky twice, 6 months apart. Then you create a triangle using the two orbital positions of the earth and the star, and work out the distance by solving the triangle. This apparently works for objects up to ~150 light years away.

My question is, would it be possible to establish an observation lab on Mars, or say one of the moons of Saturn, and use that station together with an observatory on Earth to get the same effect? If so, how much better would our measurements be?

Love the show,

Todd Freed
Idaho, USA

What do you think?

[GlentoranMark]

Yes most definitely. Parallax uses the diameter of the Earth's orbit which is roughly 300,000,000km. Mars or Saturn have a much larger orbit (Mars, is 450,000,000km and Saturn is 3,000,000,000km). Using a far bigger baseline will give a greater degree of accuracy.

If the camera's on Voyager and Pioneer were any good, we could use these to measure parallax but I think that the Hipparcus Satellite that measured stellar Parrallax in  the 80's and 90's gave a far greater degree of accuracy than anything that was available in the 70's.

[Bored chemist]

You can only measure parallax to the resolution of the telescope you are using.I don't know the figures but it might be that the size of a 'scope we could get to Mars would be too small to take advantage of the larger baseline for measuring parallax.