# Algerbra in Astrophysics

1. May 30, 2009

### log(3.14)

I am realy quite terrible at rearranging equations, I wonder if anyone could help?

How can I rearrange : m-M=5log10(d/10) to give d=?

Thanks for any imput.

2. May 30, 2009

### Cyosis

First divide by 5, $(m-M)/5=\log_{10}(d/10)$. To get get rid of the log_10 you take 10^ on both sides.

$$10^{\frac{m-M}{5}}=\frac{d}{10}$$

Now multiply by 10.

3. May 30, 2009

### log(3.14)

Cheers! This helps alot!

4. Jun 9, 2009

### peeyush_ali

what is this simple calculation has to do with "Astrophysics" ...???

5. Jun 9, 2009

### protonchain

This is the calculation for magnitudes. It's the bane of all new undergraduate astrophysics students :tongue:

6. Jun 9, 2009

### Wallace

Stupid backwards magnitudes! I've seen even seasoned astronomers get in a verbal tangle using the wrong adjective to describe some magnitude (i.e. 'as high as' instead of 'as low as' or vice versa). No wonder beginners have trouble...

7. Jun 9, 2009

### Chronos

Magnitude is a pretty obscure and confusing measure of brightness. Think 2 to the fifth power.