What Is the Fermi Gamma-ray Space Telescope?
The Fermi Gamma-ray Space Telescope is a NASA spacecraft. It is in space studying the most powerful sources of radiation in the universe. Radiation is energy that is in the form of light or of moving particles that are smaller than atoms. The most extreme type of radiation is gamma rays.
What Are Gamma Rays?
Light energy comes in many different forms. People can only see a small portion of the different types of light. This light is part of the electromagnetic spectrum. This spectrum is made up of all the types of electromagnetic, or EM, radiation in the world and possibly in the universe. EM radiation travels in waves, and each type has a different wavelength
, which is the light that people can see, has medium-length waves. Radio
waves have the longest wavelengths. Microwaves
light waves also are longer than visible light waves. Ultraviolet
"UV") rays, X-rays
and gamma rays
all have wavelengths that are shorter than visible light. The shorter the wavelength, the more energy the radiation has. Gamma rays have the shortest wavelengths; therefore they have the most energy.
Gamma rays have more than 1 billion times the energy of visible light. Gamma rays have so much energy they could harm people on Earth. People are protected from gamma rays by Earth's atmosphere. The atmosphere absorbs gamma rays, preventing them from affecting life on Earth. Because gamma rays cannot penetrate Earth's atmosphere, scientists use satellites in space to study them.
Why Is NASA Studying Gamma Rays?
Gamma rays come from the most extreme places in the universe. NASA is studying them because scientists want to learn more about the high-energy environments in the universe that make gamma rays. Gamma rays often come from objects like black holes and exploding stars.
Gamma rays sent out by objects embedded inside galaxies greatly affect the space around these objects and how these galaxies evolve. By studying gamma rays, NASA can better understand how the laws of physics work in the extreme environments found in the distant universe.
How Does Fermi Work?
The Fermi telescope has two main instruments. It has a large telescope that finds gamma rays with 10 million to more than 300 billion times the energy of visible light.
The spacecraft also has detectors that observe gamma-ray bursts. Gamma-ray bursts are brief flashes of gamma rays. Scientists think most of these bursts come from exploding stars that become black holes as their cores collapse.
More than half of the known gamma-ray sources are mysterious. Scientists do not know what causes the gamma rays to be emitted from these sources.
The information from Fermi is sent back to scientists on Earth. The scientists use the data to create pictures of the objects Fermi studies. These pictures help scientists discover the sources of gamma rays.
What Is NASA Learning From Fermi?
Fermi was launched June 11, 2008, and will spend at least five years observing the high-energy universe. Fermi was first named GLAST. GLAST stood for Gamma-ray Large Area Space Telescope. After GLAST was launched and started its work, it was renamed after scientist Enrico Fermi.
Enrico Fermi studied physics, which is the science of matter, forces, energy and motion. Scientists who study physics are called physicists. Enrico Fermi studied high-energy physics including gamma rays. The Fermi telescope is helping NASA learn more about Enrico Fermi's theories.
With the Fermi telescope NASA is making discoveries almost every day. Fermi is discovering new supermassive black holes. These are the largest type of black holes.
Fermi is also finding new pulsars. Pulsars are collapsed stars that emit repeated pulses of energy. Fermi finds pulsars that can only be found by measuring gamma rays.
Fermi's most exciting discoveries are yet to come.
More About Fermi:
Fermi Gamma-ray Space Telescope
What Is a Black Hole?
Fermi Music Video
See Where Fermi Is Flying
Fermi Educator Activities →
Measuring the Electromagnetic Spectrum →
Heather R. Smith/NASA Educational Technology Services