Ask An Astronomer Anything At All About Astronomy (XIV)

These posts are getting pretty popular. A particularly rich haul of questions this week.


1) Is there any evidence other than redshifts for the expansion of the Universe ?
Yes.

2) Is there any way of explaining redshifts and the cosmic microwave background that could bring back the idea of a Steady State Universe ?
No.

3) If aliens find us, will we have to use their name for Earth instead of Earth ?
Yes.

4) Can we detect aliens on other planets by looking for gases in their atmospheres ?
Yes.

5) What is the escape velocity of Jar Jar Abrahams and is there a way to reduce this to zero ?
Indeed.

6) How do you know black holes exist ?
The usual way, really.

7) What's the general sort of error when estimating the mass of a galaxy ?
Your mum.

8) Does it make much of a difference if you use Einstein's law of gravity instead of Newton's to estimate the mass of a galaxy ?
Not really.

9) How is the mass of a galaxy cluster determined ?
Quite badly.

10) Could gamma ray bursters explain the Fermi paradox ?
No.

11) What are you planning to research for the rest of the year ?
Galaxies.

12) Why are the planets so far away ?
Because gravity is pathetic.

13) Should we throw a big barbecue when the Milky Way collides with Andromeda ?
Probably not.

14) If all the stars exploded, how long would it take for all the heavy elements to decay ?
Bloody ages.