Exclusive Edition - The Ultimate Field Guide to Photography: Buy Now!
Visit our Online Shops

Sign up for free

Newsletters

Once a month
get new photos
and expert tips.

Perseus Black Hole

Click the size you would like to download:

A view of the central region of the Perseus galaxy cluster, one of the most massive objects in the universe, shows the effects that a relatively small but supermassive black hole can have millions of miles beyond its core. Astronomers studying this photo, taken by the Chandra X-ray Observatory, determined that sound waves emitted by explosive venting around the black hole are heating the surrounding area and inhibiting star growth some 300,000 light-years away. "In relative terms, it is as if a heat source the size of a fingernail affects the behavior of a region the size of Earth," said Andrew Fabian of Cambridge University.
Photograph courtesy NASA/CXC/IoA/A. Fabian et al.
INSTRUCTIONS FOR DOWNLOADING WALLPAPER
For Windows 95 or Higher
  1. Determine which size is appropriate for your monitor.
  2. Click the size you wish to download. (See the top of this page.)
  3. After the image appears in your browser, click the right-hand button on your mouse.
  4. On the menu that pops up, select SET AS WALLPAPER or SET AS BACKGROUND.

For Mac OS X
  1. Determine which image size is appropriate for your monitor.
  2. Click the size you wish to download. (See the top of this page.)
  3. After it appears in your browser, drag the image onto your desktop.
  4. From the Apple menu select SYSTEM PREFERENCES.
  5. Select DESKTOP.
  6. In the pull-down menu marked "Collection," select CHOOSE FOLDER.
  7. Locate desired image file and double-click it.

INSTRUCTIONS FOR DELETING WALLPAPER
For Windows Users (Internet Explorer)
  1. From your desktop, click the "My Computer" icon.
  2. Once the window opens, click the following folders, in this order: Local Disk (usually C: drive)
    • Documents and Settings
    • Your Username
    • Application Data
    • Microsoft
    • Internet Explorer
  3. In the "Internet Explorer" folder, you will find a file called "Internet Explorer Wallpaper.bmp."
  4. To delete this file, click the file name with your mouse, then right-click and scroll down the menu to the "delete" option. Or simply hit the "delete" key on your keyboard.
  5. The wallpaper image will remain until the computer is restarted. To delete from view without restarting the computer, right-click anywhere on an open area of the desktop, scroll down and select "Properties." (This will open the "Display Properties" window.) Click on the "Desktop" tab, select a different background and click "OK." This will change your desktop background immediately.

For Mac OS X
  1. Locate the "Applications" folder in the Macintosh hard drive and choose "System Preferences."
  2. Select "Desktop & Screen Saver." This will show you what wallpaper is currently displayed on your desktop.
  3. To change the current photo, select a new photo from the drop-down menu.
  4. To remove the photo permanently from the desktop, locate the photo on the hard drive and drag it to the trash. This will delete the image.

SPECIAL ADVERTISING SECTION

Photo: Reflection on Yellowstone Lake, Yellowstone National Park

Photo Contest

Share your shots and you could win a trip to the Grand Canyon!

Photo: Puerto Escondido

Interactive Map

Visit Mexico with this interactive map.

Support Conservation

Photo: Two penguins

Help conserve the world's natural resources.

The Green Guide

Photo: Green flower

Get tips for helping the environment.