The average starting salary in

What is an astrophysicist?

Astrophysics / May 23, 2024

Megan (aged 4 1/2 years) wrote to us to ask as two questions: What is an astrophysicist? And where could she get an astrophysicist's toy? Phil Marshall wrote back, with some partial answers and an astrophysics investigation to get her started...

Dear Megan,

I am an astrophysicist. Nobody ever told me what an astrophysicist is, but I think I have figured it out. An astrophysicist is someone who is trying to understand how the things in the night sky work. Imagine all the things you can see in the sky at night: I don’t mean aeroplanes, or bats, or owls, or clouds, although it’s true that sometimes you can see all those things at night. I mean the things that are so high up that you can’t tell that they are moving: things in outer space, like the Moon, and the planets, and the stars, and our galaxy (the Milky Way), and all the other galaxies in the Universe. These are the things that astrophysicists are trying to find out about.

See the file attached to this post to read Phil's reply in full!
If all you want to know is what toy he suggested, well, It's a javascript simulator of the Moon's orbit around the Earth! Can you make a circular orbit? An elliptical one? What would the Moon look like to us if it was on a very elliptical orbit?

The instructions point out that in this simulation you couldn't get a fully-formed Moon into orbit by launching it off the Earth, or by having it fly in (fully formed) from outer space. We'd need a more realistic simulator to answer the question of where the Moon came from! But for making different kinds of orbits, this one's good enough. If you want to make some more complicated orbits (with the Sun and the Moon, perhaps!), try