Olav Kolbu

NASA makes a new Image Of The Day available every day in their gallery, 
complete with a fairly detailed description of what you see. This plugin 
grabs a thumbnail of the current image along with an extract of the 
accompanying description, and makes it available as a WordPress sidebar 
widget. Clicking on the thumbnail will take you to the NASA Gallery where 
you can view the full sized image and read the rest of the text. No 
local storage is used, the image and text is fetched on every view.
A friendly user let me know that the Image Of The Day is also 
available as an RSS feed. That greatly simplified this plugin and 
should make it impervious to cosmetic changes at NASA. In 
addition to this, the image width is now customizable. The height 
is calculated per image so that it stays proportional when scaled 
(down) to width.
<a href="https://downloads.wordpress.org/plugin/nasa-image-of-the-day.zip" rel="nofollow ugc">Download now!</a>
<a href="http://www.kolbu.com/2008/03/28/nasa-image-of-the-day-plugin/" rel="nofollow ugc">Support</a>

NASA Image Of The Day

Adds a sidebar widget to display the current image from the NASA Image Of The Day Gallery. Now using RSS.

ianwww

This simple plugin will grab the NASA Astronomy Picture of the Day and create a new post with it. You can choose which username it will post under as well as whether or not to go ahead and publish on creation.
Using this plugin will required you get an API Key from NASA, which is very easy to get. This does not utilize an RSS feed and does not post duplicates.

NASA Picture of the Day

Allow your readers to enjoy NASA's Astronomy Picture of the Day on your blog with this easy to use and setup plugin.

NASA Image Of The Day vs NASA Picture of the Day