. 24/7 Space News .
New Image Of Earth, Seen Through Gamma-Ray Eyes

Here we see a false-color image of the Earth in three gamma-ray energy bands, analogous to the colors red (lower energy), green (mid energy) and blue (higher energy) in the visible spectrum. For the complete caption and print-resolution versions, see the links at the end of this article. Image credit: NASA/CGRO/EGRET/ Dirk Petry.
Greenbelt MD (SPX) Mar 29, 2005
A NASA-funded scientist has produced a new type of picture of the Earth from space, which complements the familiar image of our "blue marble".

This new picture is the first detailed image of our planet radiating gamma rays, a type of light that is millions to billions of times more energetic than visible light.

The image portrays how the Earth is constantly bombarded by particles from space. These particles, called cosmic rays, hit our atmosphere and produce the gamma-ray light high above the Earth.

The atmosphere blocks harmful cosmic rays and other high-energy radiation from reaching us on the Earth's surface.

"If our eyes could see high-energy gamma rays, this is what the Earth would look like from space," said Dr. Dirk Petry of NASA Goddard Space Flight Center in Greenbelt, Md. "Other planets - most famously, Jupiter have a gamma-ray glow, but they are too far away from us to image in any detail."

Petry assembled this image from seven years of data from NASA's Compton Gamma-Ray Observatory, which was active from 1991 to 2000. The Compton Observatory orbited the Earth at an average altitude of about 260 miles (420 km).

From this distance, the Earth appears as a huge disk with an angular diameter of 140 degrees. The long exposure and close distance enabled Petry to produce a gamma-ray image of surprisingly high detail. "This is essentially a seven-year exposure," Petry said.

The gamma rays produced in the Earth's atmosphere were detected by Compton's EGRET instrument, short for Energetic Gamma-Ray Experiment Telescope.

In fact, 60 percent of the gamma rays detected by EGRET were from Earth and not deep space. Although it makes a pretty image, local gamma-ray production interferes with observations of distant gamma-ray sources, such as black holes, pulsars, and supernova remnants.

Petry created this gamma-ray Earth image to better understand the impact of "local" cosmic-ray and gamma-ray interactions on an upcoming NASA mission called GLAST, the Gamma-ray Large Area Space Telescope.

GLAST is planned for launch in 2007. Its main instrument, the Large Area Telescope, is essentially EGRET's successor.

In 1972 and 1973 the NASA satellite SAS-II captured the first resolved image of the Earth in gamma rays, but the detectors had less exposure time (a few months) and worse energy resolution

Petry, a member of the GLAST team at NASA Goddard, is an assistant research professor at the Joint Center for Astrophysics of the University of Maryland, Baltimore Country. A scientific paper describing his work is available at:

Related Links
Astrophysics abstract by Dirk Petry
Compton Gamma-ray Observatory
Gamma-ray Astronomy
Search SpaceDaily
Subscribe To SpaceDaily Express

Spring Begins With Equinox On March 20
Cambridge MA (SPX) Mar 16, 2005
The long, cold, snow-laden winter of 2004-05 officially comes to its much-anticipated end at 7:33 a.m. Eastern Standard Time on Sunday, March 20th (12:33 p.m. Greenwich Mean Time that same day).

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once

credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly

paypal only

The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.