# Uranus' closest approach to earth and its interval

1. Oct 14, 2014

### BOAS

Hello,

I am looking for a website that contains information such as the interval between earth and uranus' closest approach. I can't seem to find exactly what I am looking for, so I was wondering how difficult it would be to calculate this.

I am at a loss where to start though...

Any pointers or info would be greatly appreciated,

thanks!

2. Oct 14, 2014

### Doug Huffman

I suspect that you will have to integrate the apsides Uranus and Earth.

3. Oct 14, 2014

### Bandersnatch

Depends on how accurate you want to be.

Do you want to know the interval between the time Uranus is in opposition(which would be close to a year)?
Do you want to take into account Uranus' rather siginificant orbital eccentricity(that'll come out to something close to 84 years)?
Or, maybe you want to know the closest possible approach(within some error bars), taking into account both planets' eccentricities? Then you'd have to include apsidal precession, and the result would be in the order of 100000 years.

All the calculations are similar to that of calculating the interval between when two hands of a clock meet.

What's the level of precision you're looking for?

4. Oct 14, 2014

### BOAS

The first one - Actually, what you have said makes perfect sense. The clock hand analogy is very useful, and I think I can investigate this further, under the assumption of circular orbits.

Thanks.

5. Oct 14, 2014

### SteamKing

Staff Emeritus
Unless you're some kind of orbital genius, it's probably not recommended.

Organizations like the Jet Propulsion Laboratory keep tabs on the orbits of various bodies in the solar system by producing ephemerides (singular, ephemeris). The CPA of Uranus apparently has already occurred for this year (Oct. 7):

http://in-the-sky.org/news.php?id=20141007_13_100