A week ago, sky-watchers were bundling up to take in the Geminid meteor shower. But tonight, there’s an even more powerful show coming to the sky. In North America, a total eclipse of the moon begins at about 1:30 a.m. Eastern (Tuesday morning).
Lunar eclipses are cool, but slow. They’re not like solar eclipses which last a few minutes at most; the shadow of the Earth is quite large, and it takes the Moon a while to move through it (also unlike a solar eclipse, lunar eclipses are perfectly safe to watch with your eyes, with binoculars, or through a telescope without protection). Not only that, there are two parts to the shadow: the outer penumbra, which is very difficult to see when it falls on the Moon, and the much darker umbra, which is what really casts the Moon into the dark. In other words, things really gets started when the Moon moves into the umbra.
If it’s cloudy where you are, or you’re on the wrong side of the planet, never fear: you can still get a look because NASA is hosting a live chat and video feed of the eclipse! JPL has set up a Flickr page for people to post their pictures of the eclipse, too. If you Americans miss this eclipse, you’ll have to wait over three years before the next one, which occurs on April 14, 2014.
For more details, check out the rest of Phil’s post at Bad Astronomy.
80beats: Astronomers Display the Eclipse of a Star With Amazing Thermal Images
Bad Astronomy: Solar Eclipse, From Space!
Bad Astronomy: The July eclipse, from 12,000 meters up
Image: Anthony Ayiomamitis
The gold ring around your finger may symbolize “till death do us part” for you, but for scientists, it poses a problem.
That shiny band probably cost a small fortune at the jewelry store, but gold is actually abundant on the Earth’s surface (which helps explain why it’s the ideal form of money). The difficulty is, when scientists apply what they know about how the solar system formed, it’s hard to explain how all that gold (and other precious metals that bond easily to iron, like palladium and platinum) got into the Earth’s crust, where bling-loving humans could get at it. A new study in Science sets forth an explanation: In the Earth’s younger days, impacts by huge objects—perhaps even one as big as Pluto—may have brought it here.
To explain this theory, let’s start with the most dramatic impact in our planet’s history: the one that formed the moon and re-melted the solidifying Earth in the process.
Moon rocks brought back during the Apollo missions led to the now widely accepted theory that the moon formed when a Mars-size object crashed into early Earth. Energy from the impact would have spurred the still forming Earth to develop its mostly iron core. When this happened, iron-loving metals should have followed molten iron down from the planet’s mantle and into the core. But we know that gold and other iron-lovers are found in modest abundances in Earth’s mantle. [National Geographic]
Remember one year ago, when NASA’s LCROSS mission (Lunar Crater Observation and Sensing Satellite) blasted the moon to kick up a plume of debris? The satellite’s first look at that plume saw that, yes, there was water ice there, much to DISCOVER’s delight. One year later, scientists have published an in-depth analysis of the LCROSS plume and found that there might be even more water than they first thought: In certain places, the moon could be twice as wet as the Sahara Desert.
“It’s really wet,” said Anthony Colaprete, co-author of one of the Science papers and a space scientist at NASA Ames Research Center at Moffett Field, Calif. He and his colleagues estimate that 5.6% of the total mass of the targeted lunar crater’s soil consists of water ice. In other words, 2,200 pounds of moon dirt would yield a dozen gallons of water. [Wall Street Journal]
China successfully launched its second lunar probe on Friday, taking another step towards its goal of becoming a full-fledged space power. The probe, named Chang’e-2, made several maneuvers over the weekend to correct its trajectory, and is expected to reach the moon’s orbit this week.
The first Chang’e probe (they’re named after a Chinese moon goddess) orbited the moon for 16 months before self-destructing in a controlled impact with the lunar surface. This second craft is expected to return better data, because it will orbit closer to the surface than its predecessor and carries a higher resolution camera.
Chang’e-2 will orbit 100 kilometers above the moon’s surface and drop down to 15 kilometers on a mission to take detailed pictures of a candidate landing area for a follow-on craft, Chang’e-3, that is expected to be launched toward the end of 2014 or early 2015. [Science Insider]
The area of interest is known as the Bay of Rainbows, and the head of China’s lunar exploration program, Wu Weiren, says it’s the top choice for a landing spot.
Is there less of the moon to love than there used to be?
Yesterday came the news that our natural satellite might have shrunk 100 meters in diameter in relatively recent geologic time. The Lunar Reconnaissance Orbiter found a plethora of scarps across the lunar surface, far more than we knew about before. These cliff-like features can appear on Earth from tectonic shifts, but there’s no continental drift on the moon. Thus, the most likely explanation is: The moon shrunk. If it did, the surface would buckle under the pressure and create these scarps. Astronomers say that the gradual cooling of the moon’s interior probably caused the shrinkage.
Don’t worry about the tides disappearing, though. “Recent” means a different thing to geologists than to everyone else, and in this case it has taken a billion years for the moon to shrink in diameter just 0.003 percent.
For plenty more on the find, check out Phil Plait’s post at Bad Astronomy.
Bad Astronomy: The Moon Is Shrinking!
80beats: Study: There’s Water on the Lunar Surface, but Inside It’s Bone Dry
80beats: Found on the Moon: A Soviet Laser Reflector That Was Lost for 40 Years
Wet. Dry. Wet. Dry. You’d think the moon were a vacuum cleaner infomercial.
A series of studies in the last few years has raised our hopes that the moon is not completely dry—researchers have said that it’s still drier than the driest places on Earth, but some small amount of water ice is there. Then, this afternoon, along comes another study to reassert that the interior of the moon is drier than bone-dry.
For his paper in Science, Zachary Sharp peered into the lunar samples brought back to Earth by the Apollo missions. Where previous studies of those Apollo rocks suggested water ice was locked inside the minerals, Sharp’s assessment focuses on the chlorine in the sample because it could tell him about the moon’s history.
Most scientists think the moon was born when a huge object roaming the inner solar system — something about the size of Mars — smashed into the embryonic Earth. Debris from the collision coalesced to form the moon. As it cooled, an ocean of magma covering its surface began to crystallize. Sharp and his colleagues studied what happened to two isotopes of the element chlorine during that process [Science News].
They went to investigate solar wind-stirred storms in our planet’s magnetic field, but, after working for three years, two NASA solar-powered probes faced a dark demise, trapped in the Earth’s shadow. NASA researchers now think they can give the twin satellites another shot by altering their courses and sending them instead to study the moon.
NASA launched the probes in 2007 as a set of five identical satellites in the THEMIS Mission (Time History of Events and Macroscale Interactions during Substorms), meant to orbit Earth and send information during brief (2-3 hour) “substorms” when the magnetic field surrounding the Earth releases stored energy from solar winds. To understand the start of these “space tornadoes” responsible for the northern and southern lights, NASA placed the probes in very precise orbits, but for two craft that meant, one day, they would face prolonged battery-draining time in the Earth’s shadow.
“When we realized that the satellites would be going into very deep shadows, we started thinking of different methods for saving them–even before they were launched,” lead scientist Vassilis Angelopoulos, at the University of California, Berkeley, told Discovery News. “We realized that if we had enough fuel to change their orbits, the moon’s gravity would start pulling them up.”[Discovery News]
1969: “We landed on the moon. It’s dry.”
2008: “Excellent, we were wrong: It’s not totally dry.”
2010: “Actually, we may have been very wrong about that: There could be even hundreds of times more water there than we thought.”
That last statement is the latest in a rising tide of announcements of water on the moon; DISCOVER covered when the news broke in March, and now the study is out in the Proceedings of the National Academy of Sciences. To sum up: After reanalyzing moon samples from the Apollo landings and meteorites of lunar origin, a team led by Francis McCubbin calculated a water content of 64 parts per billion to 5 parts per million. That’s paltry compared to even the driest places on Earth. But, they write, “This lower limit range of water contents is at least two orders of magnitude [100X] greater than the previously reported value for the bulk Moon, and the actual source region water contents could be significantly higher.”
As exciting as that is, it raises the question: How did we miss this for 41 years?
Robot steps are what you take, walking on the moon.
A group of Japanese satellite makers called the Space Oriented Higashiosaka Leading Association (SOHLA) says that it will spend more than $10 million to put a humanoid, bipedal robot on the moon by 2015. Maido-kun would hitchhike on board a moon mission by the Japanese space agency JAXA that year and plant the country’s flag on our planet’s natural satellite. And maybe it will walk around—if it can keep from falling over:
Designing a robot that can balance and move on two legs will be a major challenge, says Roger La-Brooy of the Royal Melbourne Institute of Technology in Australia. “Human beings are relatively unstable, and when designing robots for unpredictable terrain, three legs are better than two.” If the robot were to fall over, it could have trouble getting up again, says Rodney Brooks, a roboticist at MIT [New Scientist].
Four decades ago, the Soviet Union put a reflector on the moon able to bounce laser signals back to the Earth. There was just one problem: They lost it.
But now the marooned reflector has been found, thanks to the determined hunting of University of California, San Diego researchers. NASA’s Lunar Reconnaissance Orbiter, in orbit around the moon, photographed the landing area where the USSR’s Luna 17 mission dropped off the missing reflector, Lunokhod 1, in 1970. The photos turned up a faint reflective dot, and the team thought that was it.