A Moondog, captured over Hampton Bays, New York in December 2011. Credit: Jeff Schultz
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You’ve probably heard of — and likely have even seen — a Sundog, the atmospheric phenomenon that creates rainbow-colored blobs or arcs of light on either side of the Sun. But did you know the Moon can have ‘dogs’ too? Also known as mock moons, false moons, or the scientific name of paraselenae, Moondogs aren’t seen as often as Sundogs. However, the conditions needed to create either of the ‘dogs’ are about the same. This great image of a Moondog, above, by Jeff Schultz is a perfect example of the kind of night you might see this gorgeous phenomenon.
What are the secrets to how Moondogs are produced?
A bright Moondog on January 20, 2012 seen in Wiltshire, England. Credit: Richard Fleet
Moondogs are seen most often in the winter when ice crystals may be present in the atmosphere. But they can appear anytime of the year when hexagon-shaped ice crystals might be high in the sky, or also when thin cirrus or cirrostratus clouds are just right. What happens is that the ice crystals or clouds refract the moonlight, creating blobs or arcs of light to the left and right of the Moon, or sometimes just on one side.
Also, the Moon usually needs to be full or nearly full, along with being low in the sky for the effect to be produced. The angular separation of the light blobs from the Moon is usually 22 degrees.
Sometimes, a full halo of light around the Moon will also appear in conjunction with the Moondogs; other times smaller arcs of light will be part of the effect, but often Moondogs appear without any other effects.
Moondogs can appear colorful like a Sundog or ‘shine’ with a light similar to the Moon.
A Moondog seen over Adelaide, Australia on November 28, 2012. Credit: Ian Musgrave.
Moondogs are seen in both hemispheres, as this image from Ian Musgrave in Australia attests, but it seems that the effect is seen most often the farther north you are in the northern hemisphere and the farther south you are in the southern hemisphere.
You never know exactly when you might be lucky enough to see a Moondog, so we recommend looking at the Moon every night! Also, don’t forget to wink at the Moon, too.
For more detailed information and images of Moondogs, Sundogs and other optical effects, Richard Fleet (the photographer who captured the second image in this article) has a great website: “Glows, Bows and Haloes.”
Venus and the Moon on 1-10-13 from Tucson, Arizona. Credit: Robert Sparks
For the past week or so, we’ve had either a waxing or waning crescent Moon (save for the New Moon on January 11) and astrophotographers have been out in full force capturing the beauty of this sliver of light, and sometimes, like the image above by Rob Sparks (hale_bopp37 on Flickr) even a little Earthshine. Enjoy these stunning photos from our readers around the world!
Luna, January 14, 2013. Credit and copyright: Raymond GilchristThe 2% waxing crescent Moon at sunset, January 12, 2013. Credit and copyright, Tavi Greiner.Waxing crescent Moon on January 14, 2013 from London, England. Credit and copyright: Sculptor Lil on Flickr.The crescent Moon taken at sunrise on January 9, 2013 from Carmyllie, Scotland. Credit and copyright: Mike Walton.Earthshine on January 15, 2013 from Kuala Lumpur. Credit and copyright: Shahrin Ahmad.The crescent Moon -- the 'easy way' -- a hand-held camera, no tripod, just a Lumix DMC-FZ48 at maximum optical zoom. Credit and copyright: Daniel Fischer.
Astrophotographer (and blogger) Daniel Fischer notes that his image, above, was taken freehand with a simple camera, “a ‘work’ of a few seconds,” he said. “Might encourage others to give it a try with their own cameras.”
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
Artist's conception of the twin GRAIL spacecraft, called Ebb and Flow. Credit: NASA/JPL-Caltech
As a fond farewell, here are some of the final images taken by the GRAIL MoonKAM educational cameras on board Ebb and Flow, the twin spacecraft for the mission. This footage was shot just three days prior to when the mission ended with the planned impacts on a rim of a crater near the lunar north pole. At that point in the mission, the spacecraft had lowered their orbit to only about 11 km above the lunar surface. While these images aren’t of the highest of resolution, they provide a great sense of what it would be like to orbit close to the Moon. Additionally, they are an inspiration to school children. With MoonKAM (Moon Knowledge Acquired by Middle School Students) the cameras took more than 115,000 total images of the lunar surface, and imaging targets were proposed by middle school students from across the country and the resulting images returned for them to study.
The two probes were purposely crashed into the Moon because they no longer had enough altitude or fuel to continue science operations.
When the Moon was receiving its highest number of impacts, so was Earth. Credit: Dan Durda
Some questions about our own planet are best answered by looking someplace else entirely… in the case of impact craters and when, how and how often they were formed, that someplace can be found shining down on us nearly every night: our own companion in space, the Moon.
By studying lunar impact craters both young and old scientists can piece together the physical processes that took place during the violent moments of their creation, as well as determine how often Earth — a considerably bigger target — was experiencing similar events (and likely in much larger numbers as well.)
With no substantial atmosphere, no weather and no tectonic activity, the surface of the Moon is a veritable time capsule for events taking place in our region of the Solar System. While our constantly-evolving Earth tends to hide its past, the Moon gives up its secrets much more readily… which is why present and future lunar missions are so important to science.
Take the crater Linné, for example. A young, pristine lunar crater, the 2.2-km-wide Linné was formed less than 10 million years ago… much longer than humans have walked the Earth, yes, but very recently on lunar geologic terms.
It was once thought that the circular Linné (as well as other craters) is bowl-shaped, thus setting a precedent for the morphology of craters on the Moon and on Earth. But laser-mapping observations by NASA’s Lunar Reconnaissance Orbiter (at right) determined in early 2012 that that’s not the case; Linné is actually more of a truncated inverted cone, with a flattened interior floor surrounded by sloping walls that rise up over half a kilometer to its rim.
On our planet the erosive processes of wind, water, and earth soon distort the shapes of craters like Linné, wearing them down, filling them in and eventually hiding them from plain sight completely. But in the Moon’s airless environment where the only weathering comes from more impacts they retain their shape for much longer lengths of time, looking brand-new for many millions of years. By studying young craters in greater detail scientists are now able to better figure out just what happens when large objects strike the surface of worlds — events that can and do occur quite regularly in the Solar System, and which may have even allowed life to gain a foothold on Earth.
Most of the craters visible on the Moon today — Linné excluded, of course — are thought to have formed within a narrow period of time between 3.8 and 3.9 billion years ago. This period, called the Late Heavy Bombardment, saw a high rate of impact events throughout the inner Solar System, not only on the Moon but also on Mars, Mercury, presumably Venus and Earth as well. In fact, since at 4 times its diameter the Earth is a much larger target than the Moon, it stands to reason that Earth was impacted many more times than the Moon as well. Such large amounts of impacts introduced material from the outer Solar System to the early Earth as well as melted areas of the surface, releasing compounds like water that had been locked up in the crust… and even creating the sorts of environments where life could have begun to develop and thrive.
(It’s been suggested that there was even a longer period of heavy impact rates nicknamed the “late late heavy bombardment” that lingered up until about 2.5 billion years ago. Read more here.)
In the video below lunar geologist David Kring discusses the importance of impacts on the evolution of the Moon, Earth and eventually life as we know it today:
“Impact cratering in Earth’s past has affected not only the geologic but the biologic evolution of our planet, and we were able to deduce that in part by the lessons we learned by studying the Moon… and you just have to wonder what other things we can learn by going back to the Moon and studying that planetary body further.”
It’s these sorts of connections that make lunar exploration so valuable. Keys to our planet’s past are literally sitting on the surface of the Moon, a mere 385,000 km away, waiting for us to just scoop them up and bring them back. While the hunt for a biological history on Mars or resource-mining an asteroid are definitely important goals in their own right, only the Moon holds such direct references to Earth. It’s like an orbiting index to the ongoing story of our planet — all we have to do is make the connections.
Learn more about lunar research at the LPI site here, and see the latest news and images from LRO here.
A very creative and stunning use of perspective, timing and distance! BASE jumper Dean Potter walks a highline at Cathedral Peak in Yosemite National Park just as the Moon rises. This was shot with a zoom lens from over a mile away, and is part of a bigger project for National Geographic called The Man Who Can Fly.
LROC view looking obliquely of the south rim of Aristarchus from the west (NASA/GSFC/Arizona State University)
Flying over at an altitude of 135 km, NASA’s Lunar Reconnaissance Orbiter captured this lovely oblique view of the crater Aristarchus, looking down at the 40-km (25-mile) -wide crater’s southern rim from the west.
The broad flank of Aristarchus’ 300-meter (980-foot) central peak and surrounding hills can be seen at left, casting lengthening shadows in the setting sun.
Named after the Greek astronomer who first proposed a controversial heliocentric model for the Solar System in the 3rd century BCE, Aristarchus is a prominent crater located near the Moon’s northwestern limb within the geologically-diverse Oceanus Procellarum — the “Ocean of Storms.” Surrounded by rays of bright ejecta that extend down its stepped rim, the floor of Aristarchus drops 3.7 km (2.3 miles) below the surrounding lunar landscape.
The bright material seen in the ejecta streaks seems to echo the patterns of light and dark material lining the slopes of Aristarchus’ central peak, suggesting that they may be the made of similar material.
Detail of the 4.5-km-long central peak of Aristarchus (NASA/GSFC/Arizona State University)
The impact that created Aristarchus an estimated 450 million years ago excavated subsurface material, melting and spraying it tens of kilometers over the surrounding plateau. It’s thought that the central peak is likely composed of the same stuff, dredged up by the impact and frozen in place.
Future lunar explorers, should they ever visit this region, would be able to collect samples from the base of the central peak and compare them to samples from the bright rays to see if they match up, allowing researchers to learn about the composition of the material underlying the plateau from rocks scattered conveniently around the surface… this is the beauty of such (relatively) recent craters! The digging’s already been done for us.
The Moon and Jupiter above the dishes in Canberra, Australia. Credit: Carlos Orue.
The full Moon today is considered a bonus for 2012, since it is the 13th full Moon of the year. But this full Moon has also been a bonus in the sense that we’re getting several nights in a row of nearly full Moons. According to Universe Today’s Phases of the Moon App, the face of the Moon on the night of the 25th was 96% illuminated; on the 26th it was 99% illuminated; the night of the 27th/morning of the 28th was the full Moon, (officially, the Moon was most full at 10:21 UTC (4:21 EST this morning), and tonight, the 28th, the face of the Moon is again 99% illuminated. And if you’re enjoying a wintery landscape like I currently am, the brilliance of the Moonlight on snow is bright enough to keep you awake at night.
Enjoy some great astrophotos submitted for photographers around the world of the bonus — and final — full Moon of 2012.
The last full Moon of 2012 — the Full Cold Moon, as seen from the James C. Veen Observatory near Lowell, Michigan. Credit: Kevin on Flickr.
The last full moon of the year as seen from the Middle Eastern Technical University Physics department in Ankara, Turkey. Credit: Nükleer Kedi
Closeup of Tycho Crater on Dec. 23, 2012. Credit: Fred Locklear
Closeup of the Moon on Dec. 26, 2012. Credit: César Cantú
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
Captured on camera by astrophotographer Rafael Defavari from his location in São Bernardo do Campo, Brazil, this video shows the Moon passing in front of Jupiter during an occultation event on December 25, 2012. Nice work!
The video plays at 5x actual speed.
Although Jupiter appeared to be “right next to” the Moon on Christmas night from our viewpoint here on Earth, in reality the two worlds were 388 million miles (625 million km) apart. The Moon blocked the view of the giant planet for a full hour and ten minutes.
‘Tis the season for lunar occultations, too… the last one occurred on November 28, and the next will be on January 22, 2013.
See more photos of the Dec. 25 event from viewers in Brazil here.
Color-composite of Dione made from raw Cassini images acquired on Dec. 23, 2012. (NASA/JPL/SSI. Composite by J. Major.)
Although made mostly of ice and rock, Saturn’s moon Dione (pronounced dee-oh-nee) does have some color to it, as seen in this color-composite made from raw images acquired by Cassini on December 23.
700 miles (1120 km) wide, Dione is covered pole-to-pole in craters and crisscrossed by long, bright regions of “wispy line” terrain — the reflective faces of sheer ice cliffs and scarps that are too steep for darker material drifting in from Saturn’s E ring to remain upon.
The composite was assembled from raw images captured in red, green and blue visible light wavelengths by Cassini from a distance of 154,869 miles (249,238 km).
The view above looks at a region on Dione’s mid-northern hemisphere. The bright-walled crater in the center surrounded by warmer-hued terrain is named Creusa, and the long rift system next to it is Tibur Chasmata, which runs north-to-south. Dione’s north pole is to the upper left.
Dione’s heavily cratered areas are most common on its trailing hemisphere. Logically, a moon’s leading hemisphere should be the more heavily cratered, so it has been hypothesized that a relatively recent impact spun Dione around 180 degrees. The moon’s small size mean that even a modest-scale impact could have done the job.
Relative sizes of Earth, Moon and Dione (J. Major)
Dione orbits Saturn at a distance of 209,651 miles (377,400 km), closer than our Moon is to us.
Lunar and Planetary Rovers covers both the manned rovers used on the final three Apollo lunar missions with the unmanned rovers used to explore the surface of Mars - under one book. Photo Credit: NASA/Jack Schmitt
40 years ago on December 19, 1972, Apollo 17 splashed down on Earth, marking the end of the manned moon missions. The astronauts came back with a treasure trove of rocks collected in 22 hours of extra-vehicular activity on the lunar surface, including “orange” soil that ended up coming from an ancient volcano.
Twitter wasn’t around back then, but anyone tuning into several Twitter accounts recently week would have a chance to experience what it could it have been like. Using mission transcripts and historical accounts of Apollo 17, these folks took it upon themselves to tweet the Apollo 17 mission, moment by moment, as “live” as possible.
Universe Today caught up with two of the tweeters. This is an edited version of what they said about the experience.
Liz Suckow (@LizMSuckow), a NASA contract archivist who tweeted on her own time
Researching a mission is divided into two parts, prelaunch and flight. For prelaunch, I use whatever official NASA documents, histories, and relevant astronaut and mission controller autobiographies I can find.
From what I’ve seen on the missions I’ve tweeted, until Apollo, no prelaunch conversation was transcribed at all. For Apollo, the last hour or so before liftoff is on the mission transcript. So, I can schedule those tweets. But, prelaunch activities for the astronauts start as long as 10 hours before liftoff. So, I use whatever resources I can to find references to the time of important events, and the rest of the prelaunch scheduling is educated guesswork. Flight is easy.
I have been trying to tweet as if I was the Johnson Space Center public affairs officer during the particular mission. When I joined Twitter in November of 2010 and was looking for accounts to follow, I came across a dead feed from JSC, I can’t remember the account name, that tweeted what had happened during a shuttle mission in real time.
Apollo 17, the only lunar mission to launch at night. Image Credit: NASA/courtesy of nasaimages.org
I thought, “Wow, that’s cool! Somebody ought to do that for the historical missions.” The celebration of the 40th anniversary of Apollo was still a big deal at NASA at the time, and the next mission up was Apollo 14. I figured someone else at NASA would have the same idea, but it was never mentioned. So, I figured I would do it on my personal account, just to see if it could be done and if anybody else (even if it was only a few people) liked the idea.
I am definitely going to be doing another one. I think the next anniversary is either Gordon Cooper‘s Mercury flight in May 2013, or the first Skylab missions. Not quite sure how I want to handle Skylab yet, may throw that one open to followers for ideas. Why do I do it? I do it because it is fun. Sometimes, I get so mentally involved the mission I get excited for what’s coming next as I am scheduling the tweets (even though I know full well what’s going to happen).
Buck Calabro (@Apollo17History), space fan who live-Tweeted along with Thomas Rubatscher
I’m live tweeting because I’m interested in Apollo. It’s a life-long interest. I myself live Tweet mostly by actually typing the tweet into HootSuite.com or Twitter.com. I have collaborated with Thomas by creating a spreadsheet of candidate tweets that he can upload into HootSuite’s bulk uploader for time-delayed tweeting.
My tweets mostly center around the command module pilot, Ron Evans. He spent three days all by himself in the CM, doing photography, mapping and other experiments. Not exactly the same sort of fame that the moonwalkers got. It’s a different kind of grit. Imagine being Evans, as AMERICA goes around the limb of the moon, completely cut off from every human being in the universe. Nothing but some fans, pumps and procedure to keep you going.
I have no plans for leveraging the Tweets. I’ll probably do another one someday. It’s a lot of work. As far as resources, I prefer source material. I have copies of the original transcripts for ground-to-air communications. The Apollo Lunar Surface Journal is a treasure trove of images and transcripts for the lunar surface portion of the mission, and the Lunar and Planetary Institute has an extensive catalog of imagery by camera magazine (which can be found in the transcripts.) NASA has scanned vast quantities of Apollo-era documentation, and the experiment results are likewise mostly available in the public domain.
