Lunar Water as Old as the Moon
NASA/GSFC/Arizona State University
Signatures for water from deep under the lunar crust have been found in the central peaks of Bullialdus Crater, indicating the water was there when the moon formed.
On June 22 and 23, the Earth's only natural satellite put on a dazzling show. Although the 'supermoon' phenomenon isn't exactly an astronomical term, and it's not an event of any great scientific consequence, it captivated the world. The cosmic coincidence of the moon being at its full phase as it made its closest approach (perigee) in its elliptical orbit, caused the 2013 supermoon to be 14 percent larger in the sky (when compared to its furthest point in orbit, or apogee) and 30 percent brighter, according to NASA. It rapidly became a beautiful astronomical spectacle.
Several of our @Discovery_Space Twitter friends who were lucky to have clear skies shared their views of this lovely celestial opportunity -- a selection of which we've showcased here.
Sean Parker, Twitter: @seanparkerphoto
"Tonight's Supermoon was considered a wanning supermoon, but still a supermoon nonetheless! Here is a 3-photo HDR image of the supermoon rising over downtown Tucson, Arizona."
"Super Moon from north Tampa, FL at 6:50 AM Monday. Competition with sunrise."
Adam Ait, Twitter: @braindrink
"Supermoon through an 80mm Meade, taken with an iPhone."
Ian Kluft, Twitter: @ikluft
"I got pic of #supermoon rise Sat from Mt Lassen in Lassen Volcanic Nat'l Park."
The moon probably had water when it first formed four and a half billion years ago, according to a new study.
Research reported in the journal Nature Geoscience, found evidence of water that was brought to the surface from deep within the lunar mantle by a series of ancient impacts.
"I think it would be very tough to have this water be anywhere other than original to the material that formed the moon," said the study's lead author Rachel Klima of Johns Hopkins University.
"I don't think this was cometary water that was somehow mixed in and excavated back out, or solar wind water. I think this had to be water that was initially there when the materials forming the moon accreted, and what we found supports that idea."
The new water signatures, in the form of hydroxyl molecules, were detected in the central peak of Bullialdus Crater on the moon's near side, according to Klima.
Hydroxyls are molecules consisting of an oxygen atom connected to a hydrogen atom. The pairing is often seen as a substructure of a water molecule.
"Hydroxyls can form when hydrogen in the solar wind flux hits the minerals in the rocks on the lunar surface," said Klima.
"That tends to happen in cooler areas, and there have been signs that it migrates with the lunar day. So basically when it's cooler it will form and stick to the surfaces, and when it gets warmer later in the lunar day it will move."
When Klima first detected hydroxyl in her spectroscopic readings, she assumed it was solar wind generated surface hydroxyls, similar to what had been seen previously.
"But looking at the crater in more detail and at different times during the lunar day, I found there was no change in the hydroxyl signature," said Klima.
Klima and colleagues were also unable to detect any hydroxyls in the surrounding lunar soil. The only hydroxyls were in the crater's central peak, indicating that it had been dredged up from deep underground.
"It was only in the center of the crater where the rocks from the deepest part of that area had been brought up to the surface, that we saw this hydroxyl signature," said Klima.
"This crater is only about 60 kilometers across, but it occurs on the rim of a larger impact basin, which would have excavated much deeper.
"So we have a two-stage excavation with a big-impact event bringing material up from very deep, and the smaller crater impacting into this material bringing it up to the surface."
Klima estimates the hydroxyl-embedded rocks may have been up to 69 kilometers below the lunar surface, prior to impact.