April 6, 2020

Review: The Kaguya Lunar Atlas.

On Sale Now from Springer Books!

You’ve never seen the Moon like this before… On September 14th, 2007, SELENE, or the SELenological and ENgineering Explorer rocketed out of JAXA’s Tanegashima Space Center on her way to the Moon. [Read more...]

02.04.11: Stalking an Impact.

On February 11 of this year, Stefano Sposetti and Marco Iten of Gnosca Observatory Switzerland used a Borg 125 ED refractor and a high speed video camera along with a similar setup attached to a Celestron 11 at a separate location to record a flash on the nighttime side of the then just past 1st Quarter Moon.

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AstroEvent: A Lunar Occultation.

Lunar occultations can be fun events to observe. As the moon continues its 27+ day long path around our planet, it sweeps out a 0.5 degree wide path and occasionally covers up a distant background star or planet. Such occasions can be fun events to observe, as the star winks out and later seems to pop back into existence from behind the lunar limb. Such an event occurs this Sunday, the night of March the 13-14th, as the waxing crescent Moon occults the semi-bright star Mu (µ) Geminorum.

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The Solstice Eclipse: An Update

This is just a brief update: the solstice lunar eclipse was one for the record books, a bright Danjon “L4″ and easily visible thoughout totality. A coppery red, this was one of the brightest on record for this seasoned observer… expect a more through after action report in this space later today… more pics can also be seen here at our shinny new Flickr account. Now… sleep!

…a brief nap and the astronomer’s friend, coffee, has brought with it some more processed results, including the stop motion/live footage above and the processed stills below. For those interested, I shot with a JVC Digicam afocally through the 8″SCT, while shooting stills with a piggybacked 800-1600 DSLR. The rig worked out pretty good, all in all; having WWV radio call out time signals in the background was a huge help, as I just let the video run while shooting stills at the top of each minute.

Also, our Twitter “danjon count” was a huge success, with a clean sweep for a Danjon number of L4, the brightest eclipse possible… the power of crowd sourcing in action!

Astro-Challenge: Spotting O’Neill’s Bridge.


 Area of "O'Neill's Bridge". (Photo by Author).     

The region of “O’Neill’s Bridge.” (Photo by Author).

   Sometimes the most interesting visual challenges are objects that never were. This type of “non-event” can give us pause, to wonder exactly what those skilled observers of yore might have seen… such a challenge comes to us this week in the form of the spurious lunar formation known as O’Neill’s Bridge. This formation lies on the edge of the Mare Crisium along the meeting points of two lunar headlands: Promontorium Lavinium and Olivium, respectively. In the early morning hours of July 29, 1953,observer John O’Neill reported spying a tiny fan of light shining under what appeared to be a natural arc. He was using a 4-inch refractor with a magnification of 125x to 250x. Reports confirming his observation soon spread. The troubling thing was, natural bridges such as those in the American southwest are formed most by water and erosion processes that aren’t present on the Moon. And the dimensions of O’Neill’s bridge would have to be huge; something on the order of 20 miles long and one mile high! Clearly, something odd was at work here. O’Neill’s bridge also garnered a brief controversy in the pre-space travel era when it was suggested that it might be artificial! The bridge also gathered a moment of science fiction fame in Arthur C. Clarke’s novel A Fall of Moondust

So what did O’Neill and so many others see? Are alien engineers setting up shop on our Moon, building bridges to nowhere?  Part of the mystery and solution lies in the fact that lighting angles on the Moon change dramatically from one apparition to another. Apollo 17 images show a tiny crater almost exactly centered between the two points; the thinking is that at the exact right lighting angle, the straight wall of the crater can look like a bridge between the two points, with perhaps a central peak just grabbing the sunlight to complete the illusion of an arch. A discussion of this came our way via Stephen O’Meara’s outstanding column The Secret Sky in the July 2010 edition of Astronomy magazine, and we felt it was an interesting challenge to share. O’Neill’s bridge seems to be most apparent when the sun angle is at a co-longitude of 127 degrees. This occurs about two days after Full, although the area of O’Neill’s bridge is illuminated from about 3 days after New until just past Full. Optimal viewing dates for the rest of the year are:

19:50UT October 25th

09:40UT November 24th

00:05UT December 24th

Good luck and maybe you’ll see or capture the illusion as it bridges the gap!  

The astro-word for this week is Terminator. This is one of the more ominous sounding science fiction terms mostly thanks to the killer robot movie franchise of the same name. The terminator of an object is simply the dividing line between illumination and darkness. On most populated areas on Earth, you stand directly under the terminator twice a day, once at sunrise and at sunset. On the airless Moon, the terminator can appear abrupt and sharp, and most of the intriguing detail occurs along this line. I especially like to watch crater rims catching the first or last rays of sunlight while the floors are still in darkness, or seeing the tips of the lunar peaks lit while surrounded in darkness. Just what would it be like to camp out on those lunar ridges, watching the sunrise on a two week long “day” as the Earth is perched high overhead?

Review: NASA’s Moonbase Alpha.

It’s hard to weld in a spacesuit… This week, we take a look at Moonbase Alpha. No, this isn’t a resurrection of the 70’s TV series Space: 1999 re-imagined, but NASA’s new online interactive game. We’ve been playing it for a few weeks now since its release in early July. Just how does its authenticity, educational use, and just plain fun factor stack up?

Right off, I’ll admit that we’re not much for online gaming; I get beaten regularly by my computer at chess, mastered Age of Empires II on my Razor while sitting through endless streams of meetings, and wasted a mints worth of quarters playing Asteroids as a kid. [Read more...]

AstroEvent: A Close Binary Occultation.

Astronomical occultations are always fun to catch. Unlike other astronomical events that often happen over glacial time scales, occultations happen with abrupt swiftness. And besides just being plain cool, occultations can produce real scientific value, data that you can contribute to from your own backyard… and there’s no bigger occulting body in the night sky than our own Moon. This week, I’d like to bring to your attention a fairly bright and interesting star that is currently undergoing a series of lunar occultations this year; Sigma Scorpii. This star shines at magnitude +2.9 in the heart of the constellation Scorpius and is itself a close binary difficult to separate with a telescope. This star is also known as Al Niyat, or Arabic for the “Shield of the Heart,” possibly referring to its visual proximity to brilliant Antares. Sigma Sco is itself a complex system, with a 9th magnitude companion about 20” distant.

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AstroEvent: Exploring Clavius.

This week, as the Moon moves past 1st Quarter on the 23rd toward Full on the 30th is a good time to explore the lunar environs. Specifically, I’d like to turn your attention towards Clavius crater, a prominent feature in the southern lunar highlands. One of the largest impact craters on the Moon at 152.2 miles across, it’s large enough to actually see the lunar curvature in its structure, and houses many smaller craters within its walls. It is visible starting at 9-10 days after New Moon, and presents a slightly different face each lunation. In fact, Clavius is one of the few craters that may be discerned by keen eyed viewers with the naked eye. In a small telescope, the relatively ancient structure of Clavius contrasts well with the nearby splashiness of young Tycho. Are these ancient, broad floored craters the result of impacts, or do they suggest early volcanic activity? Most of the rocks returned by Apollo astronauts were igneous and basaltic by nature, suggesting the young Moon once had a molten crust.

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Astro Event: The Closest Full Moon of the Year.

(Editor’s note: Due to a flurry of astronomical events, February’s events of the week will be released on an accelerated schedule; hang on!)

Amid the opposition of Mars, two launches out of the KSC and the Cape next week, and an exceptionally fine elongation of Mercury in the early morning skies, this weekend brings us a special treat; the closest Full Moon of the year. This Moon, known also as the Full Wolf Moon, is technically full at precisely 06:00 Universal time on Saturday morning, the 30th of January. This comes only 3 hours prior to perigee, when the Moon is closest to Earth in its orbit. At this time, the Moon will be only 217,862 miles distant, and appear 34.1’ arc minutes in size, as opposed to 29.3’ arc minutes at apogee. An added plus is that this Full Moon occurs at a very northerly declination in the constellation Cancer, and hence will be riding high for northern hemisphere viewers all night. And don’t forget ruddy Mars, just 7° degrees north of the Moon!

The astro word for this week is albedo. Think that bright silvery Full Moon is bright? Science says otherwise. Albedo is the measure of the percentage of light reflected back by an astronomical object; 100% is a full mirror, optimal reflection, and 0% is pitch black. On Earth, fresh snow reflects about 85% of the light that falls on it, and the average albedo of Earth is about 30%, depending on the amount of cloud cover and the percentage of land versus ocean presented to the Sun. In fact, this phenomenon of reflectivity may play a key role in a lesser known effect impacting global climate; that of global dimming. Now for the real shocker; the average albedo for the Moon is about 10%, slightly less than worn asphalt! Ask the Apollo astronauts; the Moon is in fact, a very grey-to-black place! The reason that this weekend’s Full Moon looks bright is that you are seeing the sum of 5% of the Sun’s reflected light crammed into an area tinier than a fingernail at arm’s length. In fact, anyone who has stood under a 99% percent eclipsed Sun, as occurred earlier this month, will tell you that even 1% of the sun’s output is still pretty bright!

Top Astronomy Events for 2010.

Ah, it’s that most hallowed time of year yet again; a time to look ahead at what astro- wonders await in 2010. Here’s a quick month-by-month rundown of the curious, unique and bizarre coming to a sky near you. Like last year, rather than bore you with a laundry list of every obscure wide conjunction and moon phase, we distilled ‘em down to the best of the best.

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07.11.09:Attack of the Lunar Rovers!

NASA plans to send new hardware back to a familiar place; the Moon. Specifically, scientists at the Planetary Science Institute in Tucson, Arizona are studying the hugely successful rover activities on Mars to see if they can be emulated in a low-cost fashion on the Moon. It isn’t generally known that much of the Moon is largely unexplored from a ground-level perspective; the early unmanned Surveyor-style landers in the 60′s were stationary, and the Apollo astronauts were restricted to nearside, equatorial landing sites. Intelligent lunar rovers would allow for extensive surveys of unexplored areas such as the South Pole Aitken Basin, one of the largest impact basins in the solar system. Rovers could also scout out future manned landing sites as well as search for that treasure of treasures; water. Unlike the Martian rovers, the signal round trip is negligible, thus allowing for near real-time control. So, when might we see this new breed of lunar robots? Well, NASA has unofficial plans to place its first rover in 2014. The Chinese however, may beat us to tasting lunar dirt with the Chang’e-3 mission in 2013…who will win the battle of the 21st century lunar rovers? Stay tuned!

Review: From Earth to the Moon.

A few years back, I unearthed a hidden gem at Zia Records in Tucson, my all time favorite of a dying breed, the local record store. That gem was HBO’s From Earth to the Moon box set, and it is still well worth hunting down. Hosted by Tom Hanks and directed by Ron Howard, it originally ran as a twelve part mini series covering the US space program through the Mercury, Gemini, and Apollo series of missions. Now that Apollo 11s’ 40th is winding down, (will anybody mark the splashdown?) the LRO and LCROSS satellites are in lunar orbit, and the Ares X-1 is ramping up for its first test flight later this year, its a good time to reflect on how we got here. [Read more...]

AstroEvent of the Week: 6.7.09: Can you spot the Penumbral?



This week, I give you what is surely the meekest of all eclipses; a very shallow penumbral eclipse. At about 5:38 Eastern Standard time on the morning of Tuesday, July 7th, the northern edge of the Moon will find itself not quite a quarter submerged in the Earth’s penumbra, the light outer part of the planet’s shadow. The geometry for most of the continental United States is not good, as the Moon will be setting in the brightening dawn twilight. So why should you care to wake up early for an almost non-eclipse? [Read more...]

AstroEvent of the Week, February 8th-15th, 2009; A Penumbral Eclipse.



This weeks’ astro-event of the week isn’t exactly a real barn-burner, but is always interesting to note, none the less; a penumbral eclipse of the Moon. This occurs around 14:38 Universal Time on Monday, the 9th of February as seen from the Pacific Rim hemisphere of the planet.

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Determine your Longitude: the Lunar Eclipse Method Part II

Hopefully, you had clear skies at your locale. My luck was pretty good… mostly clear skies through-out! My initial impressions were that of a very bright eclipse; the southern rim of the moon seemed especially bright. The color ranged from a dark blood red on the northern edge to an overall brownish glow. This seemed particularly prominent through binocs. And it was extremely cold! Temps ranged around zero Fahrenheit. The night was even punctuated by a fast pass of spy satellite USA 193, on what turned out to be its final orbit. So much for a scoop by Astroguys…

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A Lunar Eclipse Update:

A quick update concerning tonight’s Lunar Eclipse; in the event of clouds at your location, the eclipse can be viewed live via webcast on several sites. [Read more...]