Jump to content




Data sources for angular diameter

Recommended Posts

I've been trying and thus far failing to find a reliable source of data showing the angular diameters of planets (specifically Venus, Mars, Jupiter and Saturn) as viewed from Earth for each day of the year.

I'm aiming to produce a visualisation of these values using the D3 Javascript library but am unfortunately stuck at the first hurdle.

I've found the JPL Horizons web interface (HORIZONS Web-Interface) that shows ephemerides for a given planet. This gives me the distance (delta, in AU) and thus allow me to determine the angular diameter via trigonometry. Aside from that the data is in fixed-width format embedded between text, making automated parsing annoying.

Is that the best option I have or does anyone know of any other data sources that might provide me with the information in a more usable form?

Link to comment
Share on other sites

Thanks - Solex looks an interesting tool but sadly doesn't seem to allow me to export the data I need directly.

The average values on that page unfortunately don't help me as it's the variation I'm interested in. Looking at wikipedia (Angular diameter - Wikipedia, the free encyclopedia) I see there's a lot of variation between the minimum and maximum angular diameter and it's this change I'm hoping to plot over time.

I get the feeling my best option will be to import the raw data from JPL's Horizons website into mysql and then use SQL to perform trig to determine the angular diameter based on the each planet's distance per day and the average of the polar radius and equatorial radius of each planet. Accuracy isn't essential here as I'm concerned only with the relative change per day for my needs.

Edited by vince1976
Link to comment
Share on other sites

Clearly I was too tired when looking at the horizons site last night to notice the Table Settings link, which changes the data properties the site returns and allowed me to select just the target angular diameter.

I now have 10 years worth of daily data for all the planets in a format that can easily be converted to JSON for use in Javascript without any need for trigonometry.

I'll be using the Horizons site a lot more now I realise what it's capable of.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.