NASA uploads a selected astronomy picture daily as their Astronomy Picture of the Day (APOD). For a space sci-fi junkie myself, I find these pictures extremely pretty and I want to use them as my wallpapers! But obviously downloading them from NASA everyday is a huge hassle. Luckily, NASA provides open APIs that we can make use of to automate this process. The NASA open APIs can be found at https://api.nasa.gov/. To use this API, you’ll need an API key. You can generate your own key on their website. But if you’re only using this API to get their APOD once a day, you’ll be perfectly fine with their demo key (DEMO_KEY). For the rest of this article, I’ll be using DEMO_KEY to access NASA open database.

To access NASA APOD in python, we use a module called requests to make web queries:

import requests
metadata = requests.get('https://api.nasa.gov/planetary/apod?api_key=DEMO_KEY')

metadata contains metadata information of the APOD. We can use metadata.json() to retrieve a Json dictionary of these data:

print(metadata.json()['explanation'])

Above statement will print out caption for the APOD. To download the picture, we use metadata.json()['hdurl']:

import urllib
file_path, header = urllib.request.urlretrieve(metadata.json()['hdurl'], filepath)

Where filepath is the path to store the picture file.