Only 843 pounds of moon rocks exist on Earth, according to NASA.
Now, 30 years after it went missing, one of those precious rocks has been found among memorabilia belonging to former President Bill Clinton.
Miami (CNN) - A satellite whose orbit is degrading will fall back to Earth Friday afternoon, but only some of its pieces will survive the fiery ride through the atmosphere, NASA scientists said Thursday.
The pieces are not expected to come down over North America, scientists said, but where they'll likely land is something NASA expects to narrow down over the next 24 hours.
With the internet, it doesn’t take a Ph.D. in astrophysics to help find new worlds outside our solar system.
For the first time, new planet candidates have been identified with the help of the public’s analysis of NASA data. Anyone can join this effort, called Planet Hunters, for free and start helping real astronomers weed through data that might signal a never-before-seen planet.
"A quintet of Saturn's moons come together in the Cassini spacecraft's field of view for this portrait.
Janus (179 kilometers, or 111 miles across) is on the far left. Pandora (81 kilometers, or 50 miles across) orbits between the A ring and the thin F ring near the middle of the image. Brightly reflective Enceladus (504 kilometers, or 313 miles across) appears above the center of the image. Saturn's second largest moon, Rhea (1,528 kilometers, or 949 miles across), is bisected by the right edge of the image. The smaller moon Mimas (396 kilometers, or 246 miles across) can be seen beyond Rhea also on the right side of the image.
This view looks toward the northern, sunlit side of the rings from just above the ringplane. Rhea is closest to Cassini here. The rings are beyond Rhea and Mimas. Enceladus is beyond the rings.
The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on July 29, 2011. The view was acquired at a distance of approximately 1.1 million kilometers (684,000 miles) from Rhea and 1.8 million kilometers (1.1 million miles) from Enceladus."
Source: NASA(CNN) - A satellite whose orbit is degrading is likely to crash back to Earth on Friday, and 26 pieces have a good chance of surviving the heat of re-entry, NASA said Wednesday.
Despite being pretty sure that the Upper Atmosphere Research Satellite, or UARS, will re-enter the atmosphere sometime Friday, U.S. time, Mark Matney of NASA's Orbital Debris team told CNN there is no way to know where it will fall.
Because the satellite travels thousands of miles in a matter of minutes, Matney said, even minutes before re-entry it will be impossible to pinpoint an exact location. On top of that, he said, "part of the problem is the spacecraft is tumbling in unpredictable ways and it is very difficult to very precisely pinpoint where it's coming down even right before the re-entry."
NASA says most of the six-ton spacecraft is made of aluminum, which has a relatively low melting temperature and will burn up on re-entry. But about half a ton of material is likely to make it through.
You can track UARS here.
FULL STORYFrom narwhals to polar bears to even amphipods, arctic photographer Paul Nicklen has has been documenting artic wildlife for the last decade, exploring impacts they're facing from climate change. Nicklen says that with his photography, he wants people to understand that if we lose ice, we stand to lose an entire ecosystem.
FULL STORY from CNN Ideas
Vesta, the second-most massive object in the asteroid belt, is revealing its secrets. New images and video taken by the Dawn mission's framing camera are helping scientists understand how many of the asteroid's interesting features were formed.
One of those features, a circular depression in Vesta's south pole region, is several hundred miles in diameter. Scientists have been eager to take a closer look at this region since the Hubble Space Telescope first indicated its existence, several years ago.
These new images were taken from an altitude of about 1,700 miles above the asteroid's surface, and were used to establish Vesta's rotational axis and a system of latitude and longitude coordinates on the surface.
This video, from the Jet Propulsion Laboratory team managing the Dawn mission, shows Vesta from the spacecraft's perspective. The JPL team notes that Vesta, like Earth, has seasons, which is why the asteroid is only partially lit in the video. It's currently winter at Vesta's north pole.
Read more about the Dawn mission.
(CNN) - A 65-million-year-old murder mystery just got a bit more mysterious.
Which "family" of asteroids killed earth's dinosaurs?
New data from NASA's orbiting Wide-field Infrared Survey Explorer (WISE) throws doubt on a 2007 theory that blamed the death of the dinosaurs on fragments from an asteroid family called Baptistina, located between Mars and Jupiter.
Baptistina was a huge asteroid which crashed into another space rock millions of years ago, sending mountain-sized pieces flying in various directions.
"Using a digital still camera, the International Space Station Expedition Three crew captured a setting sun and the thin blue airglow line at Earth's horizon. Some of the station's components are silhouetted in the foreground. This image was taken on Sept. 16, 2001."
Source: NASAA NASA satellite is expected to re-enter Earth's atmosphere on or around Friday, September 23, according to NASA officials on Monday.
Re-entry of NASA's Upper Atmosphere Research Satellite, or UARS, was originally expected in late September or early October 2011, almost six years after its mission was complete.
"As of Sept. 18, 2011, the orbit of UARS was 133 mi by 149 mi (215 km by 240 km). Re-entry is expected Sept. 23, plus or minus a day," NASA wrote Monday in an update.
The satellite will break into pieces during re-entry, and not all of it will burn up in the atmosphere. The risk to public safety or property is extremely small, NASA says.
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