Hello everyone! Welcome to my first instructable. In this instructable, I will show you how to make a program that changes your computer’s desktop to the most recent NASA Image of the Day. These images are always stunning and the program really adds to your desktop appearance.

The NASA Image of the Day is a wonderful source of images from Earth, inside NASA, and distant galaxies. The images are always full of color, and I have yet to see one that does not go perfectly on a 1080p or less display.

This instructable contains directions for Windows 10 and the files included should mostly be usable for other similar operating systems, but it does require Java.

All files and releases are available, open-source, on my GitHub.

I hope you enjoy and learn a lot from my first instructable. If you have any advice for me, I’d love to hear it!

Update 3/27/19: Due to a new Chrome update, using the image slideshow may cause Chrome windows to flicker. This may be solved in future updates, but for now, you can set the slideshow time to one day to lower the amount the window flickers. (Solution from Chris N.) If you do set the time to one day, you can ignore the Windows Registry step.

Update 8/11/20: Version 2 is done! The biggest change is that it now corrects color issues that would happen with certain image formats.

Step 1: Set Up the Files

Start by creating a location where the images and JAR file will be. I just put my files in the folder "images" on my desktop. Download the iotd_refresh.jar file (the latest and its source code can both be found here), and put it in the folder.

Opening your startup folder by: (Windows) Opening the run dialog (type [Windows Key] + R) and typing “shell:startup” without quotes then hit enter. (Apple) Opening System Prefrences -> Users & Groups -> Login Items, then clicking '+' and finding the JAR file.

Items in startup will automatically run when you log in. If you won't be turning off your computer often, then you can skip this step and see the step later on how to manually schedule the program.

Right-click on the JAR file you just downloaded and click "Send to..." -> "Desktop". This will create a shortcut to the file on your desktop.

Move the shortcut you just created from your desktop to the startup folder.

That's it for file setup! Now for getting your computer to use it.

Step 2: Get the First Images

Now we’ll work on the folder you created earlier.

Run the JAR file by double-clicking it. If you have Java properly installed, it should run without errors, and two new files named “img” and “img2” should pop up. Running it again should keep both files.

Step 3: Change Settings

Now that the files are set up, the only thing left to do is apply the settings.

Windows: Go to your desktop, right-click, and select “Personalize.” On Windows 8-10 this will open the Settings window (pictured above), but on Windows 7 it should open the Control Panel.

Apple: Go to System Prefrences -> Desktop & Screen Saver

Within the settings, you need to change a few options:

Under the “Background” option, set the drop-down box to “Slideshow.”
Under the “Choose a Fit” menu, I selected Span, since I find that is looks the best (it will resize the image so that it is cut off at the sides, so the photo will be cut down, but there won’t be any black bars or stretching of the image.
Select the folder you created which contains the images using the “Browse” button under the “Choose albums for your slideshow” section.
You'll want the picture to change once a day.

Step 4: Scheduling Events

If you don’t want to turn your computer off often, you can use task scheduling.

Use Windows Task Scheduler:

1. Open the run dialog and type “Taskschd.msc.”

2. In the Actions pane to the right of the Task Scheduler window, click on “Create Basic Task…”

3. Give your new task a name and, if you want, a description.

4. After clicking next, select daily, click next, choose the time you want the photo refresh to be executed, then click next.

5. In this section, select the radio “Start a program,” then click next.

6. Now, either manually enter the location of the “Refresh Image.jar” file, or use browse to find it.

Click next, then Finish.

Step 5: Done!

That's it! I hope you liked this instructable, and I hope everything in it works. I may not be able to help with some problems related to setting this up, but if I can, I'd be glad to help. Please give me any advice on this instructable, too if you'd like. Thanks for reading through, and have a nice day!