Take a deep breath. You just filled your lungs with about a thousand billion,
billion oxygen molecules. There are "oxygen bars" in California where you can
actually pay for a deep breath of "O-2," but in most places on Earth, molecular
oxygen is free and abundant.
The gas makes up almost 21 percent of our planet's atmosphere and is ubiquitous.
Astronomers have just announced the discovery of this same gas in outer space.
"Here on Earth, oxygen was discovered in the 1770s," says Paul Goldsmith of the
Jet Propulsion Laboratory. "Early chemists called it "fire air" because of its
combustible properties. But it has taken us more than 230 years to finally say
with certainty that this very simple molecule also exists in space."
Goldsmith led a team of astronomers who used the European Space Agency's Hershel
Space Telescope to search for signs of molecular oxygen in star-forming clouds.
Hershel senses far-infrared radiation invisible to the human eye. It just so
happens that molecular oxygen can be seen at these long wavelengths.
Goldsmith's team found the telltale signs of "O-2" near the core of the great
Orion Nebula. The "2" in "O-2" is crucial. The oxygen we breathe on Earth is
diatomic - that is, two oxygen atoms joined together to form a dumbbell shaped
molecule. Single atoms of oxygen are highly reactive and can even be corrosive.
But when you put two oxygen atoms together - aaaah - it's a breath of fresh air.
Astronomers have long known that the reactive atomic form of oxygen is abundant
in the universe. It is found in gaseous nebulae, the atmospheres of stars, and
many other places. This new discovery by Hershel shows at long last that the
familiar diatomic form of oxygen is out there, too.
Curiously, the oxygen found by Goldsmith's team is not a free-floating gas. It
appears to be mixed up in an icy frosting which coats grains of space dust in
"This explains where some of the oxygen might be hiding," says Goldsmith. "But
we didn't find large amounts of it, and still don't understand what is so
special about the spots where we find it. The universe still holds many
Star-forming clouds tend to be dusty places, so there could be lots more O-2
hiding out there. Goldsmith says the team plans to continue their hunt for this
familiar gas in other clouds beyond the Orion Nebula. Out there, he knows, is an
elusive whiff of Earth among the stars.
For more fresh air in science news, visit science.nasa.gov.