Editor's note: Meg Urry is the Israel Munson professor of physics and astronomy and chairwoman of the department of physics at Yale University, where she is the director of the Yale Center for Astronomy and Astrophysics.
(CNN) – On Wednesday, NASA officials announced a serious problem with the Kepler satellite, the world's most successful planet-finding machine.
Since its launch four years ago, Kepler has found more than 2,700 possible planets orbiting stars other than our Sun, of which more than 100 have been confirmed. A few of these exoplanets resemble the Earth in size or mass.
Recently, three Earth-like planets were even reported to be in the habitable zone: close enough to the star they orbit that water is liquid, yet not so close that it is boiling. Planets with liquid water may well harbor life.
By Jason Moon, CNN
A meteoroid struck the surface of the moon recently, causing an explosion that was visible on Earth without the aid of a telescope, NASA reported Friday. But don't be alarmed if you didn't see it; it only lasted about a second.
"It exploded in a flash nearly 10 times as bright as anything we've ever seen before," said Bill Cooke, of NASA's Meteoroid Environment Office.
NASA astronomers have been monitoring the moon for the past eight years, looking for explosions caused by meteoroids hitting the lunar surface. It's part of a program to find new fields of space debris that could hit Earth. NASA says it sees hundreds of detectable lunar meteoroid impacts a year.
By Matt Smith, CNN
The future of NASA's planet-hunting Kepler space observatory was in question Wednesday after a part that helps aim the spacecraft stopped working, the U.S. space agency said.
Controllers found Tuesday that Kepler had gone into a "safe mode" and one of the reaction wheels needed to orient the spacecraft would not spin, Associate NASA Administrator John Grunsfeld told reporters. NASA engineers are trying to figure out whether they can get the balky part back into service or whether they can resume control by another method, Grunsfeld said.
"We're not ready to call the mission over," he said. But at roughly 40 million miles from Earth, "Kepler is not in a place where I can go up and rescue it."
The Kepler mission has identified 132 planets beyond our solar system since its launch in 2009, leading scientists to believe that most stars in our galaxy have planets circling them. It has gone into a "safe mode" with its solar panels facing back at the sun, giving controllers intermittent communication with the craft as it spins.
Chris Hadfield has conquered space. Now he's conquering the Internet, too.
A video of the Canadian astronaut singing David Bowie's "Space Oddity" from the International Space Station has been zipping around the Web at light speed since it was posted Sunday. The five-minute clip features Hadfield singing a modified version of the tune and strumming an acoustic guitar while floating through a space module, more than 200 miles above the Earth.
By Monday morning, it had more than 1 million views on YouTube, 3,000 comments on Reddit and was being widely shared across social networks.
By Elizabeth Landau, CNN
Leave it all behind and start anew on a planet no humans have occupied - how does that sound? More than 78,000 people applied to go on a one-way trip to Mars, through Mars One, an organization aiming to put four people on the Red Planet by 2023.
Apparently, they are unfazed by the idea that they can never come back or that taking showers there would not be an option.
The applications came from more than 120 countries, although the United States led with 17,324 applications, the Dutch company said.
The International Space Station crew is preparing for a spacewalk to address the leak of ammonia from a cooling system, the commander said Friday.
NASA said the crew is preparing for a "possible" spacewalk and that a decision on whether to go ahead with it is likely to come late Friday.
Cmdr. Chris Hadfield of Canada announced the plan to venture outside the space station via his Twitter account.
"Good Morning, Earth! Big change in plans, spacewalk tomorrow, Chris Cassidy and Tom Marshburn are getting suits and airlock ready. Cool!" he posted Friday.
By Buzz Aldrin, Special to CNN
Editor's note: Buzz Aldrin, best known for his Apollo 11 moonwalk, holds a doctoral degree in astronautics and, at the age of 83, continues to wield influence as an international advocate of space science and planetary exploration. Aldrin’s new book "Mission to Mars: My Vision for Space Exploration," co-authored with space journalist Leonard David, is a blueprint and strategy for American-led presence of human beings from Earth on the Red Planet Mars. He is on Twitter at @therealbuzz.
We need to get the world excited again about space exploration and have the pioneering spirit to reach beyond our boundaries and current capabilities.
I want a new generation of space explorers to feel as I did when it was my privilege to take part in the Apollo program that landed the first humans on the surface of the Moon. This is important, not only for the USA but for the rest of the world.
Let me tell you why.
Buzz Aldrin's new book is called "Mission to Mars: My Vision for Space Exploration."
By Meg Urry, Special to CNN
Editor's note: Meg Urry is the Israel Munson professor of physics and astronomy and chairwoman of the department of physics at Yale University, where she is the director of the Yale Center for Astronomy and Astrophysics
On April 27, NASA's Fermi and Swift satellites detected a strong signal from the brightest gamma-ray burst in decades. Because this was relatively close, it was thousands of times brighter than the typical gamma-ray bursts that are seen by Swift every few days. Scientists are now scrambling to learn more.
We already knew that when the biggest stars run out of fuel, they don't fade quietly away. Instead, they explode in a blaze of glory known as a supernova. These stellar explosions are often bright enough to be seen by us even though they are in galaxies billions of light-years from our own Milky Way galaxy home.
In very rare cases - such as GRB130427A (tagged with the date of its discovery) - astrophysicists are lucky enough to see energetic gamma-rays from hyperfast jets of outflowing material consisting of charged particles created during a massive star's violent death throes.
By Rich Clifford, Special to CNN
It had been a little more than four months since completing my second space shuttle mission, STS-59, on the shuttle Endeavour.
I was finishing my annual flight physical at the Johnson Space Center Flight Medicine Clinic. The words from the flight surgeon were as expected: I was in great condition with nothing of note. Then I asked the doctor to look at my right shoulder because my racquetball game was suffering.
He asked if I had pain. I told him I wasn't in pain, but my right arm did not swing naturally when I walked. This comment must have set off some alarm, because he observed my walk down the hall and quickly said he would take me downtown to the Texas Medical Center the next day.
By Nana Karikari-apau, CNN
Editor's note: The Science Seat is a feature in which CNN Light Years sits down with movers and shakers from different areas of scientific exploration. This is the ninth installment.
NASA astronaut Catherine "Cady" Coleman has logged more than 4,330 hours in space aboard the Space Shuttle Columbia and the International Space Station.
Coleman was a flight engineer on a Russian Soyuz rocket that took her to the space station in December 2010, and came back to Earth in May 2011, having spent 159 days in space. CNN followed her on this journey - called Expedition 26/27 - to get ready for the expedition, and showed segments every month of what life was like for her and her family in the year before the launch.
This month, CNN Light Years caught up with Coleman to reflect on her spaceflight experiences. Here is an edited transcript.