David Dickinson, Author at Universe Today

February 3, 2014December 23, 2015 by David Dickinson

Watch Venus as it Wanders Through the Dawn in 2014

Venus as captured by Shahrin Ahmad (@shahgazer) on January 31st, 2014. Credit- Shahgazer.net.

Are you a chronic early riser? Observational astronomy often means late nights and early mornings as daylight lengths get longer for northern hemisphere residents in February through March. But this year offers another delight for the early morning crowd, as the Venus is hanging out in the dawn skies for most of 2014.

You may have already caught sight of the brilliant world: it’s hard to miss, currently shinning at a dazzling -4.5 magnitude in the dawn. Venus is the brightest planet as seen from Earth and the third brightest natural object in the night sky after the Sun and the Moon.

Venus just passed between the Earth and the Sun last month on January 11th at inferior conjunction. Passing over five degrees north of the Sun, this was a far cry from the historic 2012 transit of the solar disk, a feat that won’t be replicated again until 2117 AD.

But February and March offer some notable events worth watching out for as Venus wanders in the dawn.

The path of Venus from February 4th to September 23rd, 2014. The first (top) graphic lays out the path as seen at dawn from latitude 30 degrees north, while the bottom lays out the path of Venus as seen from latitude 30 degrees south. Note that the orientation of the ecliptic in the top frame is set for September 23rd, while the bottom frame is set for February 4th, respectively. Created using Starry Night Education software.

This week sees Venus thicken as a 48” 16% illuminated waxing crescent as it continues to present more of its daytime side to the Earth. We’ve always thought that it was a bit of cosmic irony that the closest planet too us presents no surface detail to observers: Venus is a cosmic tease. This assured that astronomers knew almost nothing about Venus until the dawn of the Space Age — guesses at its rotational speed and surface conditions were all widely speculative. Ideas of a vast extraterrestrial jungle or surface-spanning seas of seltzer water oceans gave way to the reality of a shrouded hellish inferno with noontime temps approaching 460 degrees Celsius. Venus is also bizarre in the fact that it rotates once every 243 Earth days, which is longer than its 224.7 day year — you could easily out walk a Venusian sunrise, that is if you could somehow survive to see it from its perpetually clouded surface!

Venus also passes 4.3 degrees from faint Pluto this week on February 5^th. And while Pluto is a tough catch at over a million times fainter than Venus, it’s interesting to consider that NASA’s New Horizons and ESA’s Rosetta spacecraft are also currently off in the same general direction:

Venus and the invisible lineup of deep space missions in the same general direction this week. Also note that Venus has been skirting the non-zodiac constellation of Scutum this season! Created using Starry Night Education Software, — Venus and the invisible lineup of deep space missions in the same general direction this week. Also note that Venus has been skirting the non-zodiacal constellation of Scutum this season! Created using Starry Night Education Software.

Venus also reaches greatest brilliancy at magnitude -4.6 next week on February 11^th. Venus is bright enough to cast a shadow onto a high contrast background, such as freshly fallen snow. Can you see your “Venusian shadow” with the naked eye? How about photographically?

Venus then goes on to show its greatest illuminated extent to us on February 15^th. This combination occurs because although the crescent of Venus is fattening, the apparent size of the disk is shrinking as the planet pulls away from us in its speedy interior orbit. Can you spy the elusive “ashen light of Venus” through a telescope? Long a controversy, this has been reported by observers as a dim “glow” on the nighttime hemisphere of Venus. Proposed explanations for the ashen light of Venus over the years have been airglow, aurorae, lightning, Venusian land clearing activity (!) or, more likely, an optical illusion.

And speaking of which, the crescent Venus gets occulted by the waning crescent Moon on February 26^th. Observers in western Africa will see this occur in the predawn skies, and the rest of us will see a close pass of the pair worldwide. Can you spot Venus near the crescent Moon in the daytime sky on the 26^th?

The Moon and Venus at dawn on February 25th for observers along the U.S. Eastern Seaboard. Created using Stellarium.

In March, Venus begins the slide southward towards the point occupied by the Sun months earlier and heads towards its greatest westward elongation for 2014 on March 22^nd at 46.6 degrees west of the Sun. Interestingly, Venus is tracing out roughly the same track it took 8 years ago in 2006 and will trace again in 2022, when it will also spend a majority of the year in the dawn once again. The 8-year repeating cycle of Venus is a result of the planet completing very nearly 13 orbits of the Sun to our 8. Ancient cultures, including the Maya, Egyptians, and Babylonian astronomers all knew of this period.

Through the telescope, Venus appears at a tiny “half-moon” phase 50% illuminated at greatest elongation, a point known as dichotomy. It’s interesting to note that theoretical and observed dichotomy can actually vary by several days surrounding greatest elongation. An optical phenomenon, or a true observational occurrence? When do you judge that dichotomy occurs in 2014?

In April, one of the closest planetary conjunctions occurs of 2014 on the 12^th involving Neptune and Venus at just 40’ apart, a little over the span of a Full Moon. Can you squeeze both into an eyepiece field of view? At +7.7th magnitude, Neptune shines at over 25,000 times fainter than Venus. Neith, the spurious “moon” of Venus described by 18th century astronomers lives!

But two even more dramatic conjunctions occur late in the summer, when Jupiter passes just 15’ from Venus on August 18^th and Regulus stands just 42’ from Venus on September 5^th. Fun fact: Venus actually occulted Regulus last century on July 7th, 1959!

From there on out, Venus heads toward superior conjunction on the far side of the Sun on October 25th, to once again emerge into the dusk sky through late 2014 and 2015.

Be sure to check out these dawn exploits of Venus through this Spring season and beyond!

January 31, 2014April 26, 2016 by David Dickinson

From Webcam to Planetcam: Planetary Imaging on the Cheap

It’s a question we get often.

“What sort of gear did you use to capture that?” folks ask, imagining that I’m using a setup that required a second mortgage to pay for.

People are often surprised at the fact that I’m simply using a converted off-the-shelf webcam modified to fit into the eyepiece-holder of a telescope, along with freeware programs to control the camera, stack,and clean up images. And while there are multi-thousand dollar rigs available commercially that yield images that would have been the envy of professional observatories even a decade ago, you may just find that you have the gear lying around to start doing planetary and lunar photography tonight.

OK, I’ll admit: you do need a laptop and telescope, (things that we typically have “laying around” our house!) but these are the two priciest items on the list to get started. Living the vagabond life of a veteran, a teacher, and a freelance science writer assures that our preferred cameras for conversion are always in the double-digit dollar range.

Converted "Planetcam" installed on the 'scope. — Our first converted “Planetcam” installed on the ‘scope.

But converted webcam imaging is not new. We first read about the underground movement over a decade ago. Back in the day, amateur astrophotographers were hacking their Phillips Vesta and ToUcam Pro webcams with stunning results. Celestron, Meade and Orion later caught up to the times and released their own commercial versions for planetary imaging some years later.

A few freeware installations and the modification of a Logitech 3000 that I bought on rebate for 50$ later, and I was soon imaging planets that same night.

Just about any webcam will yield decent results, though the discontinued Phillips ToUcam Pro webcams are still the heavily sought after Holy Grail of webcam astrophotography. The modification simply consists of removing the camera lens (don’t do this with any camera that you don’t want to gut and void the warranty) and attaching a standard 1 ¼” eyepiece barrel in its place using cement glue.

For camera control, I use a program called K3CCDTools. This was freeware once upon a time, now the program costs $50 to install. I still find it well worth using, though I’ve been turned on to some equally useful programs out there that are still free. (more on that in a bit).

K3CCDTools will process your images from start to finish, but I find that Registax is great for post-image processing. Plus, you don’t want to waste valuable scope time processing images: I do the maximum number of video captures in the field, and then tinker with them later on cloudy nights.

Screen cap — A screen capture of K3CCD tools during a daytime alignment test. Note the focusing dialog (FFT) box to the right.

Stacking video captures enables you to “grab” those brief moments of fine atmospheric seeing. Many astrophotographers will manually select the best frames from thousands one by one, but I’ll have to admit we’re often impatient and find the selection algorithm on Registax does an acceptable job of selecting the top 10% of images in a flash.

And like Photoshop, a college course could be taught around Registax. Don’t be intimidated, but do feel free to experiment! After stacking and optimizing, we find the true power in making the images “pop” often lies in the final step, known as wavelet processing. A round of sharpening and contrast boosting in Photoshop can also go a long way, just remember that the goal is to apply the minimum to get the job done, rather than looking unnatural and over-processed.

Photos by author — A photo mosaic of the historic Mars opposition of 2003.

At the eyepiece, the first target hurdle is object acquisition. A standard webcam can go after bright targets such as the Moon, the Sun (with the proper filter) planets, and bright double stars. We’ve even nabbed the International Space Station with our rig using a low-tech but effective tracking method. Your field of view, however, will typically be very narrow; my webcam coupled to a Celestron C8” Schmidt-Cassegrain typically yields a field of view about 10’ on a side. You’ll want to center the object in the eyepiece at the highest power possible, then plop the camera in place.

The next battle is centering and focusing the object on the screen. An out-of-focus planet scatters light: tweaking the focus back and forth sometimes reveals the silvery “doughnut” of the planet lurking just out of view.

From there, you’ll want the object in as razor sharp a focus as possible. K3CCDTools has a great feature for this known as a Fine Focusing Tool (FFT). Some observers also using focusing masks, which can also be easily built — remember, were being cheapskates! — out of cardboard. Be sure those reflector mirrors are properly collimated as well.

Don’t be surprised if the planet initially looks over-saturated. You’ll want to access the manual controls of via the camera software to take the brightness, contrast and color saturation down to acceptable levels. I typically shoot at about 15 frames a second. Fun Fact: the “shutter speed” of the dark adapted “Mark 1 human eyeball” is generally quoted around 1/20^th of a second, slower than you’d think!

Note: all those thousands of frames of video go somewhere… be sure to occasionally clean them off your hard-drive, as it will swiftly fill up!

When you image makes a big difference as well. The best time to shoot an object is when it transits the local north-south meridian and is at its highest point above the horizon. The reason for this is that you’re looking through the thinnest possible cross-section of the often turbulent atmosphere.

Universe Today reader Scott Chapman of Montpelier, Virginia also recently shared with us his exploits in planetary webcam imaging and his technique:

A webcam image of the Mare Crisium region on the Moon. Credit-Scott Chapman

“Recently, while looking for an affordable basic telescope, to see if I really had any interest in astronomy, searches and reviews led me to purchase a 70mm refractor. The last thing on my mind was that I could expect to take any pictures of what I might see.

Previously, I had assumed that the only way to take even basic pictures of sky objects was with equipment that was way out of my price range. Imagine my surprise to learn that I could use a simple webcam that I already had sitting around!”

Like many of us mere mortal budget astrophotographers, Scott’s goal was great images at low cost. He also shared with us the programs he uses;

–SharpCap2: For capturing .avi video files from the webcam connected to the telescope.

–VirtualDub: For shortening the .avi video.

–PIPP: For optimization of stacked images.

–AutoStakkert2: Selects and stacks the best frames into a single .tiff file using a simple 3-step process. Scott notes that its “MUCH easier for a beginner to use than Registax!”

-Registax6: The latest version of the software mentioned above.

–JPEGView: For final cropping and file conversion. (I sometimes also use ye ole Paint for this).

Even after a decade of planetary imaging, some of these were new to us as well, a testament to just how far the technique has continued to evolve. Astrophotography and astronomy are lifelong pursuits, and we continue to learn new things every day.

The current camera I’m shooting with is a Logitech c270 that I call my “Wal-Mart 20$ Blue Light Special.” (Yes, I know that’s Kmart!) Lots of discussion forums exist out there as well, including the QuickCam and Unconventional Imaging Astronomy Group (QCUIAG) on Yahoo!

Some observers have even taken to gutting and modifying their webcams entirely, adding in cooling fans, more sensitive chips, longer exposure times and more.

All great topics for a future post. Let us know of your trials and triumphs in webcam planetary photography!

-Watch Dave Dickinson pit his 20$ webcam against multi-thousand dollar rigs weekly in the Virtual Star Party.

-Be sure to send those webcam pics in to Universe Today!

January 30, 2014December 23, 2015 by David Dickinson

Stormy with a Chance of Molten Iron Rain: First Ever Map of Exotic Weather on Brown Dwarfs

Think the weather is nasty this winter here on Earth? Try vacationing on the brown dwarf Luhman 16B sometime.

Two studies out this week from the Max Planck Institute for Astronomy based at Heidelberg, Germany offer the first look at the atmospheric features of a brown dwarf.

A brown dwarf is a substellar object which bridges the gap between at high mass planet at over 13 Jupiter masses, and a low mass red dwarf star at above 75 Jupiter masses. To date, few brown dwarfs have been directly imaged. For the study, researchers used the recently discovered brown dwarf pair Luhman 16A & B. At about 45(A) and 40(B) Jupiter masses, the pair is 6.5 light years distant and located in the constellation Vela. Only Alpha Centauri and Barnard’s Star are closer to Earth. Luhman A is an L-type brown dwarf, while the B component is a T-type substellar object.

More to the story: Read a “behind the scenes” account of how this discovery was made — from the proposal to the press release.

“Previous observations have inferred that brown dwarfs have mottled surfaces, but now we can start to directly map them.” Ian Crossfield of the Max Planck Institute for Astronomy said in this week’s press release. “What we see is presumably patchy cloud cover, somewhat like we see on Jupiter.”

To construct these images, astronomers used an indirect technique known as Doppler imaging. This method takes advantage of the minute shifts observed as the rotating features on brown dwarf approach and recede from the observer. Doppler speeds of features can also hint at the latitudes being observed as well as the body’s inclination or tilt to our line of sight.

But you won’t need a jacket, as researchers gauge the weather on Luhman 16B be in the 1100 degrees Celsius range, with a rain of molten iron in a predominately hydrogen atmosphere.

The study was carried out using the CRyogenic InfraRed Echelle Spectrograph (CRIRES) mounted on the 8-metre Very Large Telescope based at the European Southern Observatory’s (ESO) Paranal observatory complex in Chile. CRIRES obtained the spectra necessary to re-construct the brown dwarf map, while backup brightness measurements were accomplished using the GROND (Gamma-Ray Burst Optical/Near-Infrared Detector) astronomical camera affixed to the 2.2 metre telescope at the ESO La Silla Observatory.

A closeup of the GROND instrument (the blue cylinder to the lower left) on the La Silla 2.2-metre telescope. Credit-ESO/European Organization for Astronomical Research in the Southern Hemisphere.

The next phase of observations will involve imaging brown dwarfs using the Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) instrument, set to go online at the Very Large Telescope facility later this year.

And that may just usher in a new era of directly imaging features on objects beyond our solar system, including exoplanets.

“The exciting bit is that this is just the start. With the next generations of telescopes, and in particular the 39-metre European Large Telescope, we will likely see surface maps of more distant brown dwarfs — and eventually, a surface map for a young giant planet,” said Beth Biller, a researcher previously based at the Max Planck Institute and now based at the University of Edinburgh. Biller’s study of the pair went even more in-depth, analyzing changes in brightness at different wavelengths to peer into the atmospheric structure of the brown dwarfs at varying depths.

“We’ve learned that the weather pattern on these brown dwarfs are quite complex,” Biller said. “The cloud structure of the brown dwarf varies quite strongly as a function of atmospheric depth and cannot be explained with single layer clouds.”

A rotational surface map of Luhman 16B Credit-ESO/I. Crossfield.

The paper on brown dwarf weather pattern map comes out today in the January 30^th, 2014 edition of Nature under the title Mapping Patchy Clouds on a Nearby Brown Dwarf.

The brown dwarf pair targeted in the study was designated Luhman 16A & B after Pennsylvania State University researcher Kevin Luhman, who discovered the pair in mid-March, 2013. Luhman has discovered 16 binary systems to date. The WISE catalog designation for the system has the much more cumbersome and phone number-esque designation of WISE J104915.57-531906.1.

We caught up with the researchers to ask them some specifics on the orientation and rotation of the pair.

“The rotation period of Luhman 16B was previously measured watching the brown dwarf’s globally-averaged brightness changes over many days. Luhman 16A seems to have a uniformly thick layer of clouds, so it exhibits no such variation and we don’t yet know its period,” Crossfield told Universe Today. “We can estimate the inclination of the rotation axis because we know the rotation period, we know how big brown dwarfs are, and in our study, we measured the “projected” rotational velocity. From this, we know we must be seeing the brown dwarf near equator-on.”

The maps constructed correspond with an amazingly fast rotation period of just under 6 hours for Luhman 16B. For context, the planet Jupiter – one of the fastest rotators in our solar system – spins once every 9.9 hours.

“The rotational period of Luhman 16B is known from 12 nights of variability monitoring,” Biller told Universe Today. “The variability in the B component is consistent with the results from 2013, but the A component has a lower amplitude of variability and a somewhat different rotational period of maybe 3-4 hours, but that is still a very tentative result.”

This first mapping of the cloud patterns on a brown dwarf is a landmark, and promises to provide a much better understanding of this transitional class of objects.

Couple this announcement with the recent nearby brown dwarf captured in a direct image, and its apparent that a new era of exoplanet science is upon us, one where we’ll not only be able to confirm the existence of distant worlds and substellar objects, but characterize what they’re actually like.

January 29, 2014December 23, 2015 by David Dickinson

NEOWISE Spots Mars-Crossing Comet

NASA's NEOWISE Mission takes aim at Comet A1 Siding Spring on January 16th, 2014 when the comet was 571 million kilometres distant. Credit: NASA/JPL-Caltech

One of the big ticket astronomical events of 2014 will be the close passage of Comet C/2013 A1 Siding Spring past the planet Mars in October 2014. Discovered just over a year ago from the Australian-based Siding Spring Observatory, this comet generated a surge of excitement in the astronomical community when it was discovered that it was going to pass very close to the planet Mars in late 2014.

Now, a fleet of spacecraft are poised to study the comet in unprecedented detail. Some of the first space-based observations of the comet have been conducted by NASA’s Hubble Space Telescope and the recently reactivated NEOWISE mission. And although the comet may not look like much yet in the infrared eyes of NEOWISE, its estimated 4 kilometre in diameter nucleus is already active and shedding about 100 kilograms of dust per second.

And although an impact has been since ruled out, it’s that dust that may present a hazard for Mars orbiting spacecraft, as well as a unique scientific observing opportunity.

“Our plans for using spacecraft at Mars to observe Comet A1 Siding Spring will be coordinated with plans for how the orbiters will duck and cover, if we need to do so that,” said NASA/JPL Mars Exploration Program chief scientist Rich Zurek.

The 2014 passage of Comet A1 Siding Spring through the inner solar system. Credit: NASA/JPL-Caltech

Comet A1 Siding Spring is projected to pass within just 138,000 kilometres of Mars on October 19^th, 2014. This is one-third the Earth-Moon distance, and 10 times closer than the closest recorded passage of a comet by the Earth, which was Comet D/1770 Lexell in the late 18^th century. The comet will also miss the Martian moons of Phobos and Deimos, which have the closest orbits of any moons in the solar system at just 5,989 and 20,063 kilometres above the surface of Mars, respectively.

Assets in orbit around the Red Planet are also slated to observe the close approach and passage of Comet A1 Siding Spring, as well as any extraterrestrial meteor shower that its dust may generate.

“We could learn about the nucleus – its shape, its rotation, whether some areas on its surface are darker than others,” Zurek said in a recent NASA/JPL press release.

The rovers Curiosity and Opportunity are currently active on the surface of Mars. Above in orbit, we’ve got the European Space Agency’s Mars Express, and NASA’s Mars Odyssey and the Mars Reconnaissance Orbiter (MRO). These will be joined by India’s Mars Orbiter Mission and NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft just weeks prior to the comet’s passage.

“A third aspect for investigation could be what effect the infalling particles have on the upper atmosphere of Mars,” Zurek said. “They might heat it and expand it, not unlike the effect of a global dust storm.”

Just last year, Mars based spacecraft caught sight of the ill-fated sungrazer Comet C/2012 S1 ISON as it passed Mars. But that dim passage yielded a scant pixel-sized view in the eyes of MRO’s HiRISE camera; Comet A1 Siding Spring will pass 80 times closer than Comet ISON and could yield a view of its nucleus dozens of pixels across.

Though the tenuous Martian atmosphere will shield to surface rovers from any micro-meteoroid impacts, they may also be witness to a surreptitious meteor shower from the debris shed by the comet, a first seen from the surface of another world.

But engineers will also be assessing the potential hazards that said particles may posed to spacecraft orbiting Mars as well.

“It’s way too early for us to know how much of a threat Siding Spring will be to our orbiters,” said JPL’s Mars Exploration Program chief engineer Soren Madsen recently. “It could go either way. It could be a huge deal or it could be nothing – or anything in between.”

In a worst case scenario, Mars orbiting spacecraft would be shuttered and oriented to “shelter in place” as the dust from the comet passes. There’s precedent for this in Earth orbit, as precious assets such as the Hubble Space Telescope were closed for business during the Leonid meteor storm of 1998.

“How active will Siding Spring be in April and May? We’ll be watching that,” Madsen continued. “But if the red alarm starts sounding in May, it would be too late to start planning how to respond. That’s why we’re doing what we’re doing right now.”

Comet A1 Siding Spring was the first comet discovered in 2013 at 7.2 Astronomical Units (AUs) distant. From our Earth based perspective, the comet will reach opposition on August 25^th at 0.96 AU from the Earth, and approach 7’ from Mars on October 19^th in the constellation Ophiuchus in evening skies. The comet reaches perihelion just 4 days later, and is slated to be a binocular comet around that time shining at magnitude +8.

The comet nucleus itself is moving in a retrograde orbit relative to Mars. Particles from A1 Siding Spring will slam into the atmosphere of Mars — and any spacecraft that happens to be in their way — at a velocity of 56 kilometres per second. For context, the recent January Quadrantids have a more sedate atmospheric impact velocity of 41 kilometres a second.

The unfolding 2014 drama of “Mars versus the Comet” will definitely be worth keeping an eye on… more to come!

January 27, 2014December 23, 2015 by David Dickinson

How to See Planet Mercury at its Best in 2014

Looking west on January 31st 30 minutes after sunset. (Created using Stellarium).

There’s an often told anecdote that astronomer Nicolaus Copernicus never spied Mercury. And while this tale is almost certainly apocryphal, it does speak to just how elusive the innermost planet of our solar system really is.

Never seen Mercury for yourself? This final week of January offers a good time to try, as Mercury reaches greatest elongation east of the Sun on Friday, January 31^st.

This will offer northern hemisphere viewers one on the best chances to spot the fleeting world low to the west immediately after local sunset. And although we get on average six apparitions of Mercury per year – three each in the dawn and dusk – all apparitions aren’t created equal.

The approximate moment of greatest elongation occurs on January 31^st at 10:00 UT / 5:00 AM EST, when Mercury is 18.4 degrees east of the Sun. This is only 0.5 degrees shy of the smallest elongation for Mercury that can occur, as the planet reaches perihelion just three days later on February 3^rd at 0.3075 Astronomical Units (AUs) from the Sun. The last time this was surpassed was the evening elongation of February 16^th, 2013^th, and the next time it’ll be topped is October 16^th, 2015 at just 18.1 degrees from the Sun.

Path of Mercury from January 27th to February 12th. (Created using Starry Night). — Path of Mercury from January 27th to February 12th as seen from latitude 30 degrees north. (Created using Starry Night Education Software).

And though this elongation is closer than usual, this also works in the Mercury-spotter’s favor. At greatest elongation, Mercury will present a 50% illuminated 7 arc second disk, readily apparent in a small telescope. But a also means that Mercury will appear almost a full magnitude brighter than it does when it reaches greatest elongation near aphelion, as it last did on March 31^st of last year, and will do again on March 14^th of this year.

Mercury will shine at magnitude -0.4 low towards the west into this coming weekend. We managed to pick up Mercury with binoculars on January 16th and have since managed to start tracking the planet unaided since January 18th.

Mercury also has another factor going for it, in terms of the angle of the evening ecliptic. Following ahead of the Sun, Mercury occupies a space that the Sun will trace up its apparent path along the ecliptic as it begins its long slow crawl northward towards the Vernal Equinox on March 20th. This means that Mercury is almost perpendicular above the western horizon at dusk and is currently getting a maximum boost above the atmospheric murk.

Mercury also gets joined by a razor thin waxing crescent Moon just over 24 hours past New sliding by it on the evening of Friday, January 31^st. Look for the Moon five degrees to the right of Mercury on the 31^st. The Moon will be a much easier catch on the February 1^st when its 10 degrees above Mercury. And can you spy the +1 magnitude star Fomalhaut in the constellation Piscis Austrinus just 20 degrees to the south of Mercury?

The orientation of the Moon and Mercury on the evening of February 1st. Credit: Stellarium.

And speaking of the Moon, this week’s New Moon is the second of the month, a feat that repeats in March 2014 and leaves the month of February “New Moon-less…” such an occurrence in either instance is informally known as a Black Moon.

Orbiting the Sun once every 88 days, Mercury completes about 4.15 circuits of the Sun for every Earth year. From our Earthbound vantage point, however, Mercury seems to only orbit the Sun 3.15 times a year. Thus 6 elongations (3 in the dusk and 3 in the dawn) will occur every year, through 7 can occur, as last happened in 2011 and will occur again next year in 2015.

Mercury (to the lower left) and the Moon on August 15th, 2012. (Photo by author).

After this weekend, Mercury will resume its plunge towards the horizon through early February. Mercury will begin retrograde (westward) apparent motion against the starry background on February 6th before resuming direct (eastward motion) on February 27th. And although astrologers may find that “Mercury in retrograde” is a convenient “blame magnet,” they’re also falling prey to a logical fallacy known as retrofitting, as Mercury spends a longer fraction of time than any other planet “in retrograde” at about 20%!

From there, Mercury heads towards inferior conjunction between the Earth and the Sun on Saturday, February 15^th, passing just 3.7 degrees north of the solar disk. You can catch Mercury entering into the field of view of the Solar Heliospheric Observatory’s (SOHO) LASCO C3 camera from February 12th to February 18th.

And although Mercury misses this time, we’re not that far away from the next transit of Mercury across the face of the Sun on May 9^th, 2016.

Up for more? An even tougher challenge is to attempt to spot Mercury… in the daytime. We’ve noted this possibility before as Mercury reaches maximum elongation from the Sun while still in the negative magnitude range. Of course, you want to physically block the Sun out of view, and don’t even try sweeping the sky near the Sun visually with binoculars or a telescope! You’ll need a clear, blue sky for maximum contrast and a polarizing filter may help in your quest… but this should be possible under exceptional conditions.

Good luck, and be sure to send those Mercury pics in to Universe Today!

January 24, 2014December 23, 2015 by David Dickinson

Nearby Brown Dwarf Captured in a Direct Image

A direct image of a brown dwarf companion (arrowed) taken at the Keck Observatory. (Credit: Crepp et al. 2014 APJ).

A recent find announced by astronomers may go a long ways towards understanding a crucial “missing link” between planets and stars.

The team, led by Friemann Assistant Professor of Physics at the University of Notre Dame’s Justin R. Crepp, recently released an image of a brown dwarf companion to a star 98 light years or 30 parsecs distant. This discovery marks the first time that a T-dwarf orbiting a Sun-like star with known radial velocity acceleration measurement has been directly imaged.

Located in the constellation Eridanus, the object weighs in at about 52 Jupiter masses, and orbits a 0.95 Sol mass star 51 Astronomical Units (AUs) distant once every 320-1900 years. Note that this wide discrepancy stems from the fact that even though we’ve been following the object for some 17 years since 1996, we’ve yet to ascertain whether we’ve caught it near apastron or periastron yet: we just haven’t been watching it long enough.

The T-dwarf, known as HD 19467 B, may become a benchmark in the study of sub-stellar mass objects that span the often murky bridge between true stars shining via nuclear fusion and ordinary high mass planets.

Brown dwarfs are classified as spectral classes M, L, T, and Y and are generally quoted as having a mass of between 13 to 80 Jupiters. Brown dwarfs utilize a portion of the proton-proton chain fusion reaction to create energy, known as deuterium burning. Low mass red dwarf stars have a mass range of 80 to 628 Jupiters or 0.75% to 60% the mass of our Sun. The Sun has just over 1,000 times Jupiter’s mass.

Researchers used data from the TaRgeting bENchmark-objects with Doppler Spectroscopy (TRENDS) high-contrast imaging survey, and backed it up with more precise measurements courtesy of the Keck observatory’s High-Resolution Echelle Spectrometer or HIRES instrument.

An artist's conception of a T-type brown dwarf. (Credit: Tyrogthekreeper under a Wikimedia Commons Attribution-Share Alike 3.0 Unported license). — An artist’s conception of a T-type brown dwarf. (Credit: Tyrogthekreeper under a Wikimedia Commons Attribution-Share Alike 3.0 Unported license).

TRENDS uses adaptive optics, which relies on precise flexing the telescope mirror several thousands of times a second to compensate for the blurring effects of the atmosphere. Brown dwarfs shine mainly in the infrared, and objects such as HD 19467 B are hard to discern due to their close proximity to their host star. In this particular instance, for example, HD 19467 B was over 10,000 times fainter than its primary star, and located only a little over an arc second away.

“This object is old and cold and will ultimately garner much attention as one of the most well-studied and scrutinized brown dwarfs detected to date,” Crepp said in a recent Keck observatory press release. “With continued follow-up observations, we can use it as a laboratory to test theoretical atmospheric models. Eventually we want to directly image and acquire the spectrum of Earth-like planets. Then, from the spectrum, we should be able to tell what the planet is made of, what its mass is, radius, age, etc… basically all of its relevant properties.

Discovery of an Earth-sized exoplanet orbiting in a star’s habitable zone is currently the “holy grail” of exoplanet science. Direct observation also allows us to pin down those key factors, as well as obtain a spectrum of an exoplanet, where detection techniques such as radial velocity analysis only allow us to peg an upper mass limit on the unseen companion object.

This also means that several exoplanet candidates in the current tally of 1074 known worlds beyond our solar system also push into the lower end of the mass limit for substellar objects, and may in fact be low mass brown dwarfs as well.

Another key player in the discovery was the Near-Infrared Camera (second generation) or NIRC2. This camera works in concert with the adaptive optics system on the Keck II telescope to achieve images in the near infrared with a better resolution than Hubble at optical wavelengths, perfect for brown dwarf hunting. NIRC2 is most well known for its analysis of stellar regions near the supermassive black hole at the core of our galaxy, and has obtained some outstanding images of objects in our solar system as well.

The hexagonal primary mirror of the Keck II telescope. (Credit: SiOwl. A Wikimedia Commons image under a Creative Commons Attribution 3.0 Unported liscense). — The hexagonal primary mirror of the Keck II telescope. (Credit: SiOwl. A Wikimedia Commons image under a Creative Commons Attribution 3.0 Unported license).

What is the significance of the find? Free floating “rogue” brown dwarfs have been directly imaged before, such as the pair named WISE J104915.57-531906 which are 6.5 light years distant and were spotted last year. A lone 6.5 Jupiter mass exoplanet PSO J318.5-22 was also found last year by the PanSTARRS survey searching for brown dwarfs.

“This is the first directly imaged T-dwarf (very cold brown dwarf) for which we have dynamical information independent of its brightness and spectrum,” team lead researcher Justin Crepp told Universe Today.

Analysis of brown dwarfs is significant to exoplanet science as well.

“They serve as an essential link between our understanding of stars and planets,” Mr. Crepp said. “The colder, the better.”

And just as there has been a controversy over the past decade concerning “planethood” at the low end of the mass scale, we could easily see the debate applied to the higher end range, as objects are discovered that blur the line… perhaps, by the 23^rd century, we’ll finally have a Star Trek-esque classifications scheme in place so that we can make statements such as “Captain, we’ve entered orbit around an M-class planet…”

Something that’s always been fascinating in terms of red and brown dwarf stars is also the possibility that a solitary brown dwarf closer to our solar system than Alpha Centauri could have thus far escaped detection. And no, Nibiru conspiracy theorists need not apply. Mr. Crepp notes that while possible, such an object is unlikely to have escaped detection by infrared surveys such as WISE. But what a discovery that’d be!

January 23, 2014December 23, 2015 by David Dickinson

Watch: An Amazing, Mesmerizing Full Rotation of Jupiter

Jupiter as imaged by Michael Phillips on July 25th, 2009... note the impact scar discovered by Anthony Wesley to the lower left. — Jupiter as imaged by Michael Phillips on July 25th, 2009.

Jupiter is a happening place in the solar system. While bashful Mars only puts on a good show once every two year opposition period, and inner worlds such as Mercury and Venus yield no surface details to backyard observers at all, the cloud tops of Jupiter display a wealth of changing detail in even modest backyard telescopes.

And this month is a great time to start observing Jupiter, as the largest planet in our solar system just passed opposition on January 5^th. Recently, veteran astrophotographer Michael Phillips amazed us here at Universe Today once again with a stunning time-lapse sequence of Jupiter and its moons Ganymede and Io. Now, he’s outdone himself with a new full rotation compilation of the gas giant planet.

The capture is simply mesmerizing to sit and watch. At 9.9 hours, Jupiter has the fastest rotational period of any planet in our solar system. In fact, with Jupiter currently visible low to the east at sunset, it’s possible to follow it through one rotation in the span of a single long January winter night.

We caught up with Michael recently and asked him about this amazing capture. The sequence was actually accomplished over the span of five successive evenings. This made it challenging to stitch together using a sophisticated program known as WINJupos.

“While this is possible on a long winter night when it is darker longer, I typically find it easier to do over multiple nights than one long sleepless night,” Michael told Universe Today. “If you wait too many days between observations, the features will change significantly, and then two nights will not match up clearly. The seams that result from using multiple nights are tricky to stick together. I created multiple non-overlapping seams and tried to blend them out against one another as layers in my image editing software. The result is smoother, but not quite the same as a single observation.”

A 14” f/4.5 Newtonian reflecting telescope was used for the captures. “Similar weather conditions and camera settings help quite a bit to make the multiple nights’ segments match up better,” Michael noted. “Keeping the same settings, using the same location away from my house in the corner of the yard (to reduce local atmospheric turbulence) night after night gives consistent results after removing the variability of the weather.”

Planetary photography also requires special considerations prior to imaging, such as getting Jupiter high enough in the sky and at specific longitudes to get full coverage in the rotation sequence.

“I try to consider the local weather patterns and atmospheric stability (seeing), but in reality, I pushed myself to get out as much and often as I could,” Michael told Universe Today. “Typically, I try to wait until Jupiter is at the highest in the sky, as the result is looking through less atmosphere and thus more stable conditions. Sometimes, the planets jiggle around and you just want to scream ‘SIT STILL!’ Basically around the time of opposition I go out as often as it’s clear, as those are opportunities that you don’t get back again until next year.”

Jupiter reaches opposition just over once every 13 months, moving roughly one constellation eastward each time. 2013 was an “oppositionless” year for Jupiter, which won’t occur again until 2025. Michael also notes that from his observing location at 35 degrees north latitude, Jupiter currently peaks at an altitude of 77 degrees above the horizon when it transits the local meridian. “I wasn’t going to squander it waiting for perfect conditions!”

In fact, Jupiter is currently in a region in the astronomical constellation of Gemini that will be occupied by the Sun in just over five months time during the June Solstice. Currently at a declination of around 22 degrees 45’ north, Jupiter won’t appear this high in the northern sky near opposition again until 2026.

It’s also amazing to consider the kind of results that backyard observers like Michael Phillips are now routinely accomplishing. It’s an interesting exercise to compare Michael’s capture side-by-side with a sequence captured by NASA’s New Horizons spacecraft during its 2006 flyby of Jupiter:

Both sequences capture a wealth of detail, including the enormous Great Red Spot, the Northern and Southern Equatorial Belts, and numerous white spots and smaller swirls and eddies in the Jovian atmosphere.

To date, six spacecraft (Pioneer 10 and 11, Voyagers 1 and 2, New Horizons and Cassini) have made flybys of Jupiter, and one, Galileo, orbited the planet until its demise in 2003. Juno is the next in this legacy, and will be inserted into orbit around Jupiter in July 2016.

Now is the time to get out and observe and image Jupiter and its moons, as it moves higher into the sky on successive evenings towards eastern quadrature on April 1st, 2014.

Congrats to Michael Phillips on an amazing sequence!

January 21, 2014December 23, 2015 by David Dickinson

An Incredible Time-lapse of Venus Passing Through Inferior Conjunction

Some of the most amazing celestial sights are hidden from our view in the daytime sky. Or are they? We recently challenged readers to try and follow the planet Venus through inferior conjunction as it passed between the Earth and the Sun on January 11^th. Unlike the previous pass on June 6^th, 2012 when Venus made its last transit of the Sun for the 21^st century, the 2014 solar conjunction offered an outstanding chance to trace Venus’s path just five degrees from the Sun from the dusk and into the dawn sky.

Expert astrophotographers Shahrin Ahmad based in Sri Damansara, Malaysia and Paul Stewart observing from New Zealand took up that daily challenge as Venus neared the limb of the Sun, with amazing results. Now, Shahrin has also produced an amazing time-lapse sequence of Venus passing through inferior conjunction.

You can actually see the illuminated “horns” of Venus as they thin, extend, and rotate around the limb as the planet passes the Sun.

And it’s what’s more incredible is that the capture was completed in the daytime. But such a feat isn’t for the unskilled. Shahrin told Universe Today of the special safety precautions he had to take to acquire Venus so close to the Sun:

“Since Venus was getting closer each day towards conjunction, I found it far too dangerous to find visually, either using the main telescope or the finderscope.”

Instead, Shahrin relies on computerized software named Cartes du Ciel to drive his Skywatcher EQ6 mount and pinpoint Venus in the daytime sky.

“The sky in Kuala Lumpur is never clear from here, thus it rarely appears dark blue, making it almost impossible to spot Venus visually, especially when it is less than 10 degrees from the Sun.”

Shahrin elaborated further on his special solar safety precautions:

“I always start with all covers in place and the solar filter on the main telescope. I will slew the telescope to the Sun, make some slight repositioning adjustments, and then synchronize the telescope to the new position. After ensuring the Sun is visible and centered on the computer screen, I slew to Venus. Once the mount has stopped in position, I remove the solar filter and replace it with a makeshift cardboard extender mounted on the existing dew-shield. This ensures that any direct sunlight is totally blocked from entering the optics.”

Shahrin notes that 90% of the time, Venus with appear on the computer screen after aligning. Otherwise, a brief spiral search of the field will slide it into view.

Shahrin observes from his ShahGazer Observatory, a roll-off-roof observatory just outside of Kuala Lumpur. He used the Skywatcher 120ED refractor pictured for the captures, with a 2x Barlow lens to achieve a focal length of 1800mm. Shahrin’s main camera is a QHY CCD IMG132e, and the rig is mounted on a Skywatcher EQ6.

A closeup of Sharin’s barlow and camera rig. Credit: Shahrin Ahmad.

“The experience of being able to track Venus approaching inferior conjunction over the Sun afterwards is exhilarating,” Shahrin told Universe Today. “It felt like watching and waiting for a total eclipse of the Sun, but in slow motion!”

Shahrin also counts himself lucky to have had a string of clear days leading up to and after inferior conjunction.

Shahrin’s capture of Venus 5 degrees from the Sun just 8 hours before inferior conjunction may also be a record. That’s a closer apparent separation than our visual sighting of Venus 7 hours and 45 minutes after inferior conjunction on January 16th 1998 as seen from North Pole Alaska, when the planet passed 5.5 degrees from the limb of the Sun.

“I’ve also noticed that in some of the photos, we can see a slight ‘glint’ of sunshine on part of Venus’ atmosphere,” Shahrin noted to Universe Today. “(This sighting) was actually confirmed by the RASC Edmonton Centre in Canada via their Twitter feed.”

An amazing capture, indeed. Venus is now back in the realm of visibility for us mere mortal backyard observers low in the dawn sky, shining at a brilliant magnitude -4.3. Expect it to vault up in a hurry for northern hemisphere observers as the favorable angle of the ecliptic will give it a boost in the dawn. Venus is also headed towards a spectacular 0.2 degree conjunction with Jupiter this summer on August 18th: expect UFO sightings to rise correspondingly. The Indian Army even briefly mistook the pair for Chinese spy drones early last year.

The waning crescent Moon approaches Venus on the morning of January 28th, 2014. Created using Stellarium.

Venus will spend most of 2014 in the dawn sky and is headed for superior conjunction on October 25^th, 2014. Venus spent a similar span in the dawn for the majority 2006, and will do so again in 2022. It’s all part of the 8-year cycle of Venus, a span over which apparitions of the planet roughly repeat. And the next shot we’ll have at inferior conjunction? That’ll be on August 15^th, 2015 for favoring the southern hemisphere and March 25^th, 2017 once again favoring the northern, when the planet very nearly passes as far from the Sun as it can appear at inferior conjunction at 8 degrees.

Congrats to Shahrin on his amazing capture!

-Follow the stargazing adventures of Sharin Ahmad on Google+ and as @shahgazer on Twitter

-Got pictures of Venus? Send ‘em in to Universe Today.

January 20, 2014December 23, 2015 by David Dickinson

The Moon Occults Saturn in the Dawn this Weekend

Saturn and the waning crescent Moon rising to the SE at about 4 AM local on January 25th, 2014. Created using Stellarium

Mark your calendars: the first in a series of interesting occultations of Saturn by the Moon for 2014 starts this weekend.

The year 2014 features 11 occultations of the planet Saturn by the Moon, and there are 23 total for 2014 of every planet except Neptune and Jupiter.

An occultation occurs when one foreground celestial object completely obscures another. Technically, a total solar eclipse is an occultation of the Sun by the Moon, although it’s never referred to as such. The term finds modern usage mainly for the blocking of stars and planets by the Moon. Very occasionally, an asteroid or planet can occult a distant star as well.

And yes, the modern astronomical term “occultation” traces its hoary roots back to the days when astronomy was intertwined with the pseudoscience of astrology. To this day, the term still makes some folks wonder if astronomers are secretly casting horoscopes. Trust us, you’re still on a solid astronomical footing to use the term “occultation.”

Unfortunately, the January 25^th occultation of Saturn by the Moon will only grace part of Antarctica, southern Argentina and Chile, and the Falkland Islands post-sunrise. The rest of us still will see a very photogenic pass of Saturn near the waning crescent Moon on the morning of Saturday, January 25^th. The Moon will pass just about a degree — two times its apparent width — south of Saturn for northern hemisphere observers.

The footprint for the January 25th occultation of Saturn by the Moon. dashed lines indicate where the events occurs in the daytime sky. (Created using Occult 4.0.11 software)

Both the Moon and Saturn will reside in the astronomical constellation of Libra this weekend during closest passage. The pair will rise around 2 AM local. After their brief tryst, the Moon will head towards New on January 30^th while Saturn will continue to rise successively earlier as its heads towards opposition and the start of evening Saturn observing season on May 10^th, 2014.

January 2014 is also notable for having two New Moons, an occurrence informally known as a Black Moon. This occurs again this year in March, and February 2014 is devoid of a New Moon. February is the only month that can be “missing a Moon phase” as it’s the only one shorter the synodic period of 29.5 days, in which the Moon returns to like phase.

In the telescope, Saturn will present a +0.8 magnitude disk 16” across (38” with rings from tip-to-tip). Saturn’s rings are tipped open to our line of sight by about 22 degrees in 2014, and are widening towards a maximum of 27 degrees in 2016 through 2017. If you have an equatorial telescope with tracking capability, it may be possible this weekend to follow Saturn up into the daytime sky. Though Saturn isn’t quite bright enough to see in the daytime unaided, it might just be possible to spy using binoculars on the 25^th using the nearby crescent Moon as a guide. Saturn is a tough daytime target to be sure, but it’s not impossible to acquire with a little skill and patience.

The current cycle of occultations of Saturn began on December 1^st, 2013 and ends on November 22^nd, 2014. The cycle will move progressively northward through the year.

The Moon and Saturn put on a repeat performance over almost the same exact location (this time in darkness) on April 17^th, 2014, and the best event in the cycle for North America will be the August 31^st daytime occultation of Saturn by the waxing crescent Moon.

Now for the wow factor of what you’re seeing. On Saturday morning, the Moon is just over 371,000 kilometres distant, or a little over a light second away. Saturn is over four thousand times more remote at just over 10.1 astronomical units (AUs) distant, which works out to 1.5 billion kilometres, or over 83 light minutes away. And although the Moon is over a 112 times larger in apparent diameter than Saturn as seen from the Earth, the globe of Saturn is actually over 34 times bigger.

Saturn and the Moon crossing the local meridian shortly after sunset on January 25th. Created using Starry Night Education Software.

And though we’ve been to the Moon lots since the dawn of the Space Age, only two spacecraft (Voyagers 1 and 2) have made brief flybys of the ringed world, and only one – Cassini – has orbited it. Note that China’s Chang’e-3 lander and rover are about to experience their second sunset this weekend as well from the lunar surface since landing on the Moon last month.

And although lots of planets get occulted by the Moon in 2014, no stars brighter than +1^st magnitude lie in its path. In fact, the next cycle of bright star occultations by the Moon doesn’t resume until the Moon meets Aldebaran in January 29^th, 2015.

There are, however, over a 100 lesser events involving the Moon occulting naked eye stars worldwide in 2014. Two such events occur this week as well, when the 48% illuminated Moon occults the +4.5^th magnitude star Lambda Virginis for west-central South America on the morning of January 24^th, and the occultation of the +2.8^th magnitude star Alpha Librae (Zubenelgenubi) for central Asia on January 25th.

Don’t miss these celestial events, and be sure to send those pics in to Universe Today… there’s something for everyone happening in the sky this week worldwide!

January 16, 2014December 23, 2015 by David Dickinson

A “MiniMoon” Seen Around the World

A 99% illuminated Moon within 24 hours of Full. Image Credit: Stephen Rahn.

So, did last night’s Full Wolf Moon seem a bit tinier than usual? It was no illusion, as avid readers of Universe Today know. As we wrote earlier this week, last night’s Full Moon was the most distant for 2014, occurring just a little under three hours after apogee.

The Full Moon, a "Moon Dog" halo, and a rare parhelic (or do you say Palunic?) arc as seen from North Slope Borough County, Alaska. Credit-Jason Ahrns. — The Full Moon, a “Moon Dog” halo, and a rare parhelic (or do you say Palunic?) arc as seen from North Slope Borough County, Alaska. Credit-Jason Ahrns.

Sure, the Moon reaches apogee every lunation, at a distance nearly as far. In fact, the Moon at apogee can be as far as 406,700 kilometres distant, and last night’s apogee, at 406,536 kilometres, is only the second farthest for 2014. The most distant apogee for 2014 falls on July 28^th at 3:28 Universal Time (UT) at just 32 kilometres farther away from our fair planet at 406,568 kilometres distant.

A 20 image composite shot using a Canon 60Da camera and a a 10" Newtonian telescope. Credit-Stephen Rahn. — A 20 image composite shot using a Canon 60Da camera and a a 10″ Newtonian telescope. Credit-Stephen Rahn.

What made last night’s MiniMoon special was its close proximity in time to the instant of Full phase. The July 2014 apogee, for example, will occur just a day and four hours from New phase.

The 2014 MiniMoon rising behind clouds from Hudson, Florida. Photo by author.

Of course, it isn’t the Moon that’s doing the shrinking, though you’d be surprised the stuff we’ve seen around ye ole Web even on reputable news sites over the past week. The variation of the apparent size of the Full Moon does make for an interesting study in perception. The Moon varies in size from apogee to perigee from about 29.3’ across to 34.1’. This is variation amounts to 14% in apparent diameter.

The Full MiniMoon, clouds, and Jupiter. Credit- Shaun Reynolds, Bungay UK. — The Full MiniMoon, clouds, and Jupiter. Credit– Shaun Reynolds (@shaunreylec), Bungay UK.

Here’s an interesting challenge that you can do for a one year period, requiring just a working set of eyes: observe the Full Moon for 12 successive lunations. Can you judge which one was the “SuperMoon” and which one was the “MiniMoon” without prior knowledge?

A "MiniMoon Nebula..." The Full Moon illuminating foreground clouds. The HDR visualization of the Moon was added for context. Taken with a tripod mounted Nikon P90 Bridge camera. Credit: Giuseppe Petricca of Sulmona, Abruzzo, Italy. — A “MiniMoon Nebula…” The Full Moon illuminating foreground clouds. The HDR visualization of the Moon was added for context. Taken with a tripod mounted Nikon P90 Bridge camera. Credit: Giuseppe Petricca of Sulmona, Abruzzo, Italy.

And as you can see, we also got plenty of pictures here at Universe Today from readers of the Mini-Moon from worldwide.

The MiniMoon shot using a mobile phone held up to the eyepeice of a telescope. Credit-Andrew Millarkie (@Millarkie) — The MiniMoon shot using a mobile phone held up to the eyepiece of a telescope. Credit-Andrew Millarkie (@Millarkie) Glasgow, Scotland.

The rare occurrence of an “Extreme-MiniMoon” — or do you say “Ultra?” — also sparked a lively discussion about the motion of the Moon, how rare this event is, and when it was last and will next be surpassed. A fun online tool to play with is Fourmilab’s Lunar Apogee and Perigee Calculator. Keep in mind, the motion of the Moon is complex, and accuracy for most planetarium programs tends to subside a bit as you look back or forward in time. The distances used in Fourmilab’s calculations are also geocentric, accounting for the center-to-center distance of the Earth-Moon system.

The MiniMoon versus streetlights as seen from Nueva Casarapa, Venezulua. Credit: Jose Mauricio Rozada (@jmrozada) — The MiniMoon versus streetlights as seen from Nueva Casarapa, Venezuela. Credit: Jose Mauricio Rozada (@jmrozada)

Suffice to say, this year’s Full MiniMoon was the most distant for several decades before 2014 or after.

Anthony Cook of the Griffith Observatory notes that JPL’s Horizons web interface gives a max distance for the Moon of 406,533 kilometres at 1:35 UT earlier today, 3 hours and 19 minutes prior to Full.

The Full MiniMoon glimpsed between clouds as seen from central Illinois. Credit-Matt Comerford, (@kb9uwu)

The next closest spread of apogee versus perigee occurs on November 18^th, 1994 at 1 hour and 51 minutes apart, and 2014’s Mini-Moon won’t be surpassed in this regard until May 13^th, 2052. Looking at the distances for the Moon on these dates using Starry Night, however, we get an slightly closer occurrence of 406,345 kilometres for 1994 and 406,246 kilometres for 2052.

The Full MiniMoon rising behind a stand of trees. Credit- Sculptor Lil. — The Full MiniMoon rising behind a stand of trees. Credit– Sculptor Lil.

And to top it off, the 1994 Mini-Moon was during a partial penumbral eclipse as well… we’ll leave that as a homework assignment for the astute readers of Universe Today to calculate how often THAT occurs. It should be fairly frequent over the span of a century, as the Moon has to be at Full phase for a total lunar eclipse to occur.

The MiniMoon as captured by Manish Agarwal from Rajasthan, India. — The MiniMoon as captured by Manish Agarwal (@iManishAgarwal) from Rajasthan, India.

Looking over a larger span of time, @blobrana notes on Twitter that closer occurrences of apogee versus Full Moon with the same approximate circumstances as 2014 also occurred on October 29^th 817 AD (with a 1 hour and 38 minute difference) and won’t occur again until December 20^th, 2154. If research can prove or disprove that these events were even more distant, then the 2014 Extreme MiniMoon was a millennial rarity indeed…

Perhaps this won’t be the last we’ve heard on the subject!