occultation Archives

July 26, 2016 by David Dickinson

Celestial Photobomb: Rare Occultation of Mercury by the Moon Set for Next Week

Mercury and the Moon over the ramparts of Assilah, Morocco. Photo by author

Have you caught sight of Mercury yet? This coming week is a good time to try, looking low to the west at dusk. We just managed to to nab it with binoculars for the first time during the current apparition this past Sunday from the rooftop of our Air BnB in Casablanca, Morocco.

Mercury is a tough grab under any circumstance, that’s for sure. Brilliant Venus and Jupiter make great guides to finding the elusive planet in late July, as it ping-pongs between the two. The waxing crescent Moon joins the scene in the first week of August, and for a very lucky few, actually occults (passes in front of ) the diminutive innermost world shortly after passing New.

Mercury (arrowed) near the Moon on the morning of June 3rd, 2016. Image credit: Dave Dickinson.

Here’s the low down on everything Mercurial, and circumstances for the coming weeks.

Mercury passes 18′ from the star Regulus on Saturday, July 30^th at 19:00 Universal Time (UT), representing the closest passage of a planet near a first magnitude star for 2016.

The Moon then reaches New phase, marking the start of lunation 1158 on August 2^nd at 20:45 UT. The Moon then moves on to occult Mercury on Thursday, August 4^th at 22:00 UT, just over 48 hours later. The occultation is visible at dusk for observers based in southern Chile and southern Argentina. The rest of us see a close pass. Note that although it is a miss for North America, viewers based on the continent share the same colongitude and will see Mercury only a degree off of the northern limb of the Moon on the night of August 4^th. Mercury shines at magnitude +0.01, and presents a 67% illuminated disk 6.3” in size, while the Moon is a slender 5% illuminated.

Occultations of Mercury for 2016. Credit: Occult 4.2. (click image to enlarge).

How early can you see the waxing crescent Moon? Catching the Moon with the naked eye under transparent clear skies isn’t usually difficult when it passes 20 hours old. This cycle, first sightings favor South Africa westward on the night of August 3^rd.

Mercury reaches greatest elongation 27.4 degrees east of the Sun 12 days after this occultation on August 16^th.

How rare is it? Well occultations of Mercury by the Moon are the toughest to catch of all the naked eye planets, owing to the fact that the planet never strays far from the Sun. Nearly all of these events go unwitnessed, as they occur mainly under daytime skies. And while you can observe Mercury in the daytime near greatest elongation with a telescope, safety precautions need to be taken to assure the Sun is physically blocked from view. Astronomers of yore did exactly that, hoping to glimpse fleeting detail on Mercury while it was perched higher in the sky above the murk of the atmosphere low to the horizon.

In fact, a quick search of ye ole web reveals very few convincing captures of an occultation of Mercury (see the video above). The closest grab thus far comes from astrophotographer Cory Schmitz on June 3^rd 2016 based in South Africa:

Image credit: — Can you see it? The Moon about to occult Mercury on June 3rd. Image credit and copyright: Cory Schmitz.

Can’t wait til next week? The Moon crosses the Hyades open star cluster this week, occulting several stars along the way. The action occurs on the morning of Friday, July 29^th culminating with an occultation of +1 magnitude Aldebaran by the 23% illuminated Moon. Texas and Mexico are well-placed to see this event under dark skies. A small confession: we actually prefer occultations of planets and stars by the waxing Moon, as the dark edge of the Moon is leading during ingress, making it much easier to witness and the exact moment the Moon blots out the object.

Still want more? The Moon actually goes on to occult Jupiter on August 6^th for the South Pacific. Viewers farther west in southeast Asia might just spy this one in the daytime. This is the second occultation of Jupiter by the Moon in a series of four in 2016.

Looking west on the evening of August 4th. Image credit: Stellarium.

Keep and eye on those planets in August, as they’re now all currently visible in the dusk sky. The Moon, Regulus and Venus also form a tight five degree triangle on the evening of August 4^th, followed by a slightly wider grouping of Venus, Jupiter and the Moon around August 25^th.

More to come on that soon. Be sure to check the planet Mercury off of your life list this coming week, using the nearby waxing crescent Moon as a guide.

August 8, 2014December 23, 2015 by Elizabeth Howell

Video: Watch The Moon Slowly Blot Out Saturn In Australia

Wow! Check out this video of the Moon passing in front of Saturn from a viewpoint in Brisbane, Australia. This type of phenomenon, called an occultation, happens when one celestial body passes in front of the other from an observer’s standpoint. You can see some information about a June 10 occultation of Saturn, for example, at this link.

“There has been a fair amount of post-processing done on the images to get to this result. The first stage was to adjust the source images so that detail was visible both on Saturn and on the Moon. This is because the two objects are quite different in brightness, and so each individual exposure results in a slightly over-exposed Moon and a slightly under-exposed Saturn,” wrote Teale Britstra, who created the video, on Vimeo.

“After initial processing, the series of images were imported into video editing software, and the resulting footage stabilized to eliminate some small tracking errors between shots,” Britstra continued.

“There was also one LARGE tracking error, where I had to physically move the telescope. This was because the Moon was sinking towards the western horizon and some nearby, large trees which would have obscured the shot had the scope not been moved. This can be seen in the resulting footage as the period where the Moon appears to slow down and slightly change direction.”

Britstra has done a few other videos on Vimeo as well, including a dramatic sunrise at Horseshoe Bay in Australia.

May 15, 2014December 23, 2015 by Nancy Atkinson

Astrophotos: Occultation of Saturn

Saturn heading behind the Moon on May 14, 2014. Credit and copyright: Silveryway on Flickr.

Observers in Australia and New Zealand had a special treat this week: watching Saturn disappear behind the Moon during an event called an occultation. (You can read all the details of how and why this happens here in our preview article.) Catching an event like this with a camera is tricky… the bright Moon can wash out the comparatively tiny (from our vantage point) planet Saturn. But here, several astrophotographers had success. Above is a nice view from Silveryway on Flickr.

See an animation of the event below from astroblogger Ian Musgrave:

An animated gif of the occulation of Saturn by the Moon on May 14, 2014. Credit and copyright: Ian Musgrave.

Ian Musgrave from Australia used a 4″ Newtonian telescope, with a “Point and Shoot” Canon IXUS attached with inifinty to infinity focussing, 3xZoom, and a 25mm eye piece. You can see his entire set of images on his website here.

Widefield view of the occultation of Saturn on May 14, 2014. Credit and copyright: Ian Musgrave.

Peter Lake, also from Australia not only took images of the event, but also did a live Hangout on G+.

“Live hangouts and driving a telescope live is a tricky business,” Peter wrote on his website. “I lost focus playing around trying to improve the image due to the thin cloud.” He added that the night sky wasn’t ideal that evening. “The full moon was shining through thin clouds, washing out a bit of the detail.”

Saturn getting ready to head behind the Moon. Credit and copyright: Peter Lake.

You can watch a replay of Peter’s Hangout below:

Saturn and the Moon diffusion. The clouds drifted across the sky, Saturn and the Moon shone bright, the view from the UK. Credit and copyright: Sarah and Simon Fisher.

Sarah and Simon Fisher from the UK captured this “diffused” view of Saturn close the Moon on the evening of May 13, 2014.

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.

May 12, 2014December 23, 2015 by Bob King

Saturn Disappears Behind the Full Flower Moon May 14 – Watch it Live

Simulation of the moon closing in on Saturn just prior to occultation. Credit: Gianluca Masi using SkyX software

Funny thing. Skywatchers are often just as excited to watch a celestial object disappear as we are to see it make an appearance. Early Wednesday morning (May 14) the Full Flower Moon will slip in front of Saturn, covering it from view for about an hour for observers in Australia and New Zealand. If you don’t live where the dingoes roam, no worries. You can watch it online.And no matter where you are on the planet, the big moon will accompany the ringed planet across the sky this Tues. night-Weds. morning.

Moon-Saturn occultation from Perth, Australia Feb. 22, 2014 captured by Colin Legg

Occultations of stars happen swiftly. The moon’s limb meets the pinpoint star and bam! it’s gone in a flash. But Saturn is an extended object and the moon needs time to cover one end of the rings to the other. Planetary occultations afford the opportunity to remove yourself from planet Earth and watch a planet ‘set’ and ‘rise’ over the alien lunar landscape. Like seeing a Chesley Bonestell painting in the flesh.

Saturn and the moon tomorrow night just before midnight as viewed from the Midwestern U.S. View faces south-southeast. Stellarium — Saturn and the moon Tuesday night (May 13) just before midnight as viewed from the U.S. Stellarium

As the moon approaches Saturn, the planet first touches the lunar limb and then appears to ‘set’ as it’s covered by degrees. About an hour later, the planet ‘rises’ from the opposite limb. Planetary occultations are infrequent and always worth the effort to see.

Seen from the northern hemisphere and equatorial regions, the nearly full moon will appear several degrees to the right or west of Saturn tomorrow night (May 13). As the night deepens and the moon rolls westward, the two grow closer and closer. They’ll be only a degree apart (two full moon diameters) during Wednesday morning twilight seen from the West Coast. Northern hemisphere viewers will notice that the moon slides to the south of the planet overnight.

Map showing the region where the occultation of Saturn will be visible. Click to get the times of Saturn's disappearance and reappearance for individual cities. Times are given in UT or Universal Time. Add 9.5 hours for Australian Central Standard Time. Credit: IOTA — Map showing the region where the occultation of Saturn will be visible. Click to get times of Saturn’s disappearance and reappearance for individual cities. Times shown are UT or Universal Time. Add 9.5 hours for Australian Central Standard Time. Credit: IOTA

Skywatchers in Australia will see the moon cover Saturn during convenient early evening viewing hours May 14:

* 8:09 p.m. local time from Adelaide

* 9:05 p.m. Brisbane

* 8:50 p.m. Melbourne

* 8:53 p.m. Canberra

* 8:56 p.m. from Sydney (More times and a map – click HERE)

Before the occultation, Saturn will shine close to the moon’s upper right and might be tricky to see with the naked eye because of glare.

Binoculars will easily reveal the planet, but a telescope is the instrument of choice. Even a small scope magnifying at least 30x will show Saturn and its rings hovering above the bright edge of the moon. Stick around. About an hour later, Saturn will re-emerge along the moon’s lower left limb.

Saturn and its moons Tuesday night May 13 around 10 p.m. CDT. Titan's the brightest and easiest. Iapetus ranges from magnitude +10 when it's west of Saturn and we see its bright hemisphere to magnitude +12 when it's west of the planet as it will be this week. Created with Meridian software — Saturn and its moons Tuesday night May 13 around 10 p.m. CDT. Titan’s the brightest and easiest moon to see at magnitude +8.5. Iapetus ranges from magnitude +10 when it’s west of Saturn and we see its bright hemisphere to magnitude +12 when it’s east of the planet. Created with Meridian software

Meanwhile, back in the western hemisphere, we’ll watch the nearly full Flower Moon make a close pass of the planet. If you’ve had difficulty finding the celestial ring bearer, you’ll have no problem Tuesday night. Take a look at Saturn’s wonderful system of rings in your telescope – they’re tipped nearly wide open this year. For even more fun, see how many moons you can spot. And don’t forget, you can watch it online courtesy of astrophysicist Gianluca Masi. His Virtual Telescope website will broadcast the occultation live starting at 10:15 Universal Time May 14 (6:15 a.m. EDT, 5:15 CDT, 4:15 MDT and 3:15 PDT).

March 26, 2014December 23, 2015 by Elizabeth Howell

Surprise! Asteroid Hosts A Two-Ring Circus Above Its Surface

Artist's impression of what the rings of the asteroid Chariklo would look like from the small body's surface. The rings' discovery was a first for an asteroid. Credit: ESO/L. Calçada/Nick Risinger (skysurvey.org)

Rings are a tough phenomenon to spot. As late as 1977, astronomers thought that the only thing in the solar system with rings was the planet Saturn. Now, we can add the first asteroid to the list of ringed bodies nearby us. The asteroid 10199 Chariklo hosts two rings, perhaps due to a collision that caused a chain of debris circling its tiny surface.

Besides the 250-kilometer (155-mile) Chariklo, the only other ringed bodies known to us so far are (in order of discovery) Saturn, Uranus, Jupiter and Neptune.

“We weren’t looking for a ring and didn’t think small bodies like Chariklo had them at all, so the discovery — and the amazing amount of detail we saw in the system — came as a complete surprise,” stated Felipe Braga-Ribas of the National Observatory (Observatório Nacional) in Brazil, who led the paper about the discovery.

Illustration of how Asteroid Chariklo may have gotten its rings. Copyright: Estevan Guzman for Universe Today.

The rings came to light, so to speak, when astronomers watched Chariklo passing in front of the star UCAC4 248-108672 on June 3, 2013 from seven locations in South America. While watching, they saw two dips in the star’s apparent brightness just before and after the occultation. Better yet, with seven sites watching, researchers could compare the timing to figure out more about the orientation, shape, width and more about the rings.

The observations revealed what is likely a 12.4-mile (20-kilometer)-wide ring system that is about 1,000 times closer to the asteroid than Earth is to the moon. What’s more, astronomers suspect there could be a moon lying amidst the asteroid’s ring debris.

Artist's impression of two rings discovered around the asteroid Chariklo. It was the first such discovery made for an asteroid. Credit: ESO/L. Calçada/M. Kornmesser/Nick Risinger (skysurvey.org) — Artist’s impression of two rings discovered around the asteroid Chariklo. It was the first such discovery made for an asteroid. Credit: ESO/L. Calçada/M. Kornmesser/Nick Risinger (skysurvey.org)

If these rings are the leftovers of a collision as astronomers suspect, this would give fodder to the idea that moons (such as our own moon) come to be from collisions of smaller bits of material. This is also a theory for how planets came to be around stars.

The rings haven’t been named officially yet, but the astronomers are nicknaming them Oiapoque and Chuí after two rivers near the northern and southern ends of Brazil.

Because these occultation events are so rare and can show us more about asteroids, astronomers pay attention when they occur. Part of the Eastern Seabord enjoyed a more recent asteroid-star occultation on March 20.

The original paper, “A ring system detected around the Centaur (10199) Chariklo”, will soon be available on the Nature website.

Source: European Southern Observatory

Artist's impression of rings around the asteroid Chariklo. This was the first asteroid where rings were discovered. Credit: ESO/L. Calçada/M. Kornmesser/Nick Risinger (skysurvey.org) — Artist’s impression of rings around the asteroid Chariklo. This was the first asteroid where rings were discovered. Credit: ESO/L. Calçada/M. Kornmesser/Nick Risinger (skysurvey.org)

March 19, 2014April 26, 2016 by Bob King

Clouds May Scotch Tomorrow’s Rare Erigone-Regulus Occultation

The bright star Regulus will disappear for observers living along the path between the red lines. The disappearance is longest - up to 14 seconds - along the center green line. Credit: Google Maps / IOTA

North America’s brightest predicted asteroid occultation may be one-upped by a much bigger occultation – a solid blanket of clouds. Asteroid 163 Erigone will cover or occult the bright star Regulus shortly after 2 a.m. Eastern Daylight Time tomorrow morning March 20. Observers along a 45-mile-wide (73-km) belt stretching from the wilderness of Nunavut to the salty seas of Bermuda could see the star vanish for up to 14 seconds. Provided they can find a hole in the clouds.

ggggggg — National forecast map for 8 p.m. EDT tonight March 19. A low pressure region is expected to bring rain and snow to the Northeast and Ontario today and overnight with clearing skies later tomorrow. Click for latest New York City weather forecast. Credit: NOAA

Overcast skies with a mix of rain or snow are predicted along virtually the entire track from the tiny berg of Cochrane in northern Ontario south through New York City, Connecticut and New Jersey. A sluggish cold front isn’t expected to clear skies until … no surprise here … after the event is over.

Bermuda, perhaps the best place to watch the occultation, crosses the eastern edge of the asteroid's shadow. The red line marks — Bermuda, perhaps the best place to watch the occultation, crosses the eastern edge (blue line) of the asteroid’s shadow. The red line marks one sigma of uncertainty in the shadow edge. Credit: Google Maps/IOTA

But there is one place where maybe, just maybe, the clouds may part to let Erigone do its job. Bermuda. The Bermuda Weather Service forecast calls for highs in the low 70s mid-week, but that balmy air may come packaged with a partly to mostly cloudy sky at the time of the occultation. A few determined observers are on their way there right now, hoping for better weather. In case the islands are socked in, some plan to rent planes to rise above the low-lying clouds typical this time of year and revel in the shadow of an asteroid. Even if clear, Bermuda lies near the eastern edge of the path. Any occultation there will be brief.

Illustration showing asteroid 163 Erigone about to cover Leo’s brightest star Regulus around 2:07 Eastern Daylight Time Thursday morning March 20, 2014. As the asteroid’s shadow passes over the ground, observers will see Regulus disappear for up to 14 seconds. Illustration: Bob King with help from photos by the ESO/NASA - — Illustration showing asteroid 163 Erigone about to cover Leo’s brightest star Regulus around 2:07 Eastern Daylight Time Thursday morning March 20, 2014. As the asteroid’s shadow passes over the ground, observers will see Regulus briefly disappear. Illustration: Bob King with ESO/NASA images

Yes, there will be more occultations, but bright ones that the public can enjoy with the naked eye are rare.

Skywatchers are nothing if not hopeful. We believe in the sucker hole, the name given to rogue clearings in an otherwise overcast sky. We are patient and steadfast when it comes to glimpsing the rarest of the rare. I know this because my friends and I have stood outside on winter mornings staring at the western sky, waiting for clouds to peel back that we might glimpse a Martian dust storm or new comet.

To find Regulus, face southwest shortly before 2 a.m. The star will be about 40 degrees high (four ‘fists’ held at arm’s length against the sky). Brilliant Jupiter shines well to its lower right. You may also notice a ‘coathangar’ or ‘backwards question mark’ shape of stars above Regulus called the Sickle of Leo. Stellarium — If it does clear tomorrow, face southwest shortly before 2 a.m. to find Leo’s brightest star Regulus. The star will be about 40 degrees high (four ‘fists’ held at arm’s length against the sky). Above is the the Sickle of Leo, shaped like a backwards question mark. Brilliant Jupiter shines well to its lower right. Stellarium

If there’s an astronomer’s credo, it’s this: “The sky might clear yet!” The latest weather word (9 a.m. March 19) for U.S. and Canadian observers indicates thinner clouds along the southern end of the track in New Jersey. Many of us considered driving to the event but changed our minds because of work, worries about weather and other commitments. Assuming the credo holds true, you’ll be able to watch Regulus disappear live from the comfort of your home thanks to the efforts of several observers planning to stream the event on the Web.

Here’s a list of streamers so far:

* Brad Timerson plans to go live with audio at 2 a.m. at a rest area along I-90 just west of Syracuse, NY.

* Ted Blank on UStream

* Steve Preston will broadcast an image of his camcorder screen

* Vagelis Tsamis will try to broadcast from Canada

* SLOOH

As always, everything depends on the weather. Let’s hope Mother Nature loses focus and lets a little clear sky slip by.

February 24, 2014December 23, 2015 by Jason Major

Watch Saturn Slip Behind the Moon

Occultation of Saturn on Feb. 22, 2014 by Colin Legg

Or, more accurately, watch the Moon pass in front of Saturn. Either way you get the same result: a beautiful video of planetary motion in action!

On the morning of Saturday, Feb. 22, the Moon drifted in front of the planet Saturn from the point of view of certain locations on Earth. Luckily one of those locations was Perth, Australia, where astrophotographer Colin Legg happens to be, and thus we all get to enjoy the fantastic results of his photographic and astronomical acumen.

Check out the video below:

The occultation — as such events are called whenever one celestial object passes in front of, or “hides,” another (the root of the word means “to conceal”) — may make it look like a tiny Saturn is getting absorbed by a giant Moon. But (obviously) they are separated by a vast distance: at the time of the occultation, 9.658 AU, or about 1,444,816,000 kilometers (897.7 million miles).

These sort of events will become a bit more common as the Moon is “headed towards a ‘shallow’ year in 2015 relative to the ecliptic; it will then begin to slowly open back up and ride high around 2025,” according to a recent Universe Today article by David Dickinson.

For those of you interested, Colin lists his equipment as a Celestron C8, f/10, prime focus. His camera is a Canon 5D2, running Magic Lantern RAW video firmware in 3x crop mode @ 1880 x 1056 resolution. Footage was taken at 1/60 sec exposure, ISO 200, 10 fps.

See more of Colin’s work on his Facebook page here.

October 8, 2013December 23, 2015 by Elizabeth Howell

Tale Of Two Moons Reveals Asteroid’s Insides

Artist's concept of the triple asteroid system: Sylvia (in the center) is surrounded by two moons, Romulus and Remus. Inset: The differentiated interior of Sylvia. Credit: Danielle Futselaar/SETI Institute

Fluffy, with a core of density. That’s what the interior of the asteroid 87 Sylvia likely looks like, astronomers say. The neatest thing about that observation? It didn’t require a drill or even a spacecraft visit. That came from watching the orbits of the asteroid’s two moons, Romulus and Remus.

The discovery illustrates the power of amateur and professional astronomers working together, the team said. On Jan. 6, dozens of small telescopes across France, Greece and Italy were set up to watch a celestial show: watching Sylvia move in front of an eleventh-magnitude star. The professionals received assistance from European Asteroidal Occultations (EURASTER), a group of professional and amateur observers, for this event.

“Observers at different locations see different parts of the asteroid, or its moons, passing in front of the star,” the team stated in a press release. “Such occultations allow exquisitely precise measurements of the relative positions and sizes of the occulting objects.”

Of the 50 observers watching the show, twelve of them saw the occultation, which lasted anywhere from four to 10 seconds depending on where the observers were.

The path of the occultation of 87 Sylvia and an eleventh-magnitude star on Jan. 6, 2013. On the map, Sylvia is represented by a black line, with its path limits marked by blue lines. Its moons -- Romulus and Remus -- are represented by green and orange lines. Credit: IMCCE — The path of the occultation of 87 Sylvia and an eleventh-magnitude star on Jan. 6, 2013. On the map, Sylvia is represented by a black line, with its path limits marked by blue lines. Its moons — Romulus and Remus — are represented by green and orange lines. Credit: IMCCE

Subsequently, the professional astronomers determined how Sylvia is shaped by using that information and combining it with other data, such as recordings of the asteroid’s light variations that happened as it spun, and some direct images using adaptive optics. The team noted that Romulus and Remus don’t seem to change in their paths in space due to Sylvia’s non-circular shape, making them conclude that it has an interior of different materials.

All told, there were 66 adaptive optics observations of the asteroids using 8 to 10 meter telescopes at the W. M. Keck Observatory, the European Southern Observatory, and Gemini North. Calculations of the system came from the Institute of Celestial Mechanics and Ephemerides Calculations (IMCCE) of the Paris Observatory.

The sun sets on Mauna Kea as the twin Kecks prepare for observing. Credit: Laurie Hatch/ W. M. Keck Observatory

“Four observers detected a two-second eclipse of the star caused by Romulus, the outermost moon, at a relative position close to our prediction. This result confirmed the accuracy of our model and provided a rare opportunity to directly measure the size and shape of the moon,” stated Jérôme Berthier, an IMCCE astronomer.

“Combined observations from small and large telescopes provide a unique opportunity to understand the nature of this complex and enigmatic triple asteroid system,” added Francis Marchis, a senior research scientist at the Carl Sagan Center of the SETI Institute, who led the research. “Thanks to the presence of these moons, we can constrain the density and interior of an asteroid, without the need for a spacecraft’s visit. Knowledge of the internal structure of asteroids is key to understanding how the planets of our solar system formed.”

The results were presented yesterday (Oct. 7) at the American Astronomical Society’s division of planetary sciences meeting in Denver.

Source: W.M. Keck Observatory

September 5, 2013April 26, 2016 by David Dickinson

See Venus and the Moon Together in the Sky on September 8

A close conjunction of Venus and the crescent Moon as seen on February 27th, 2009. (Photo by author).

Sky watchers worldwide are in for a treat Sunday evening September 8, 2013 as the waxing crescent Moon passes near the dazzling planet Venus. And for a select few, the Moon will actually pass in front of Venus, in what is known as an occultation.

The action has already started this week, as the Moon reached New phase earlier today at 7:36 AM EDT/11:36 UT. The appearance of the slim crescent Moon nearest to the September equinox marks the start of the Jewish New Year with the celebration of Rosh Hashanah, which this year began as early as it possibly can at sundown on September 4^th. As per tradition, Rosh Hashanah formally begins when the sky is dark enough for three stars to be seen. The convention established by Hillel II in 363 A.D. uses the mean motion of the Moon to fix the start dates of the Jewish luni-solar calendar, which means that occasionally Rosh Hashanah can start a day early. This also occurred in 2002.

The New Moon has also been historically an opportune time for nighttime military operations to commence —Desert Storm in 1991 and the raid against Bin Laden in 2011 were both conducted under the darkness afforded by the absence of moonlight around a New Moon. It’s yet to be seen if planners looking to conduct airstrikes on Syria are planning on taking advantage of the same conditions to begin operations soon.

Tonight, you can see the +1^st magnitude star Spica less than two degrees away from -4^th magnitude Venus. This places Venus at 100 times brighter than Spica and visible before sunset if you know exactly where to look for it.

The brightest star in the constellation Virgo, Spica is 260 light years distant and on the short list of nearby stars that will eventually go supernova. Fortunately for us, Spica is well outside of the ~100 light year radius “kill zone”.

You might just be able to spy the Moon and the -1st magnitude planet Mercury low to the west at dusk for the first time for this lunation tonight or (more likely) Friday night. This is also a great time to check out LADEE’s future home as it departs for lunar orbit from Wallops Island in Virginia on Friday night.

Hey, LADEE sitting on the pad atop its Minotaur V rocket with the slim crescent Moon in the background at dusk Friday night would be a great money shot, I’m just sayin’…

This weekend will see the Moon increase in illumination and elevation above the western horizon each evening until Spica, Venus, and the waxing crescent Moon fit within a four degree circle on Sunday night. The Moon will be 12% illuminated, while Venus is currently at a gibbous phase and 72% lit.

Looking west from latitude 30 north Sunday night from the US east coast... note that Mercury and Saturn are in the picture as well! (Created by the author in Stellarium). — Looking west from latitude 30 north Sunday night from the US east coast… note that Mercury and Saturn are in the picture as well! (Created by the author in Stellarium).

This will also present a good chance to see Venus during the daytime, using the nearby crescent Moon as a guide. This is a fun thing to try, and no gear is required! Though Venus may seem tough to find against the bright daytime sky, appearances are deceptive. With an albedo of 67% versus the Moon’s average of 14% Venus is actually brighter than the Moon per square arc second of size!

The Moon will also occult Spica on the evening of September 8^th for observers in the Middle East and Europe right around sunset. Spica is one of four bright stars that the Moon can occult in the current epoch, along with Antares, Aldebaran, and Regulus. This is also part of a series of fine occultations of Spica by the Moon ongoing from 2012 to 2014.

Sundown on September 8^th offers a special treat, as the 3-day old Moon passes less than a degree from Venus worldwide. The pair will fit easily into the field of view of binoculars or a telescope at low power and present an outstanding photo op.

And for observers based in Argentina and Chile, the Moon will actually occult Venus. Occultations are grand events, a split-second astronomical event in a universe that seems to usually move at a glacial pace. This particular occultation occurs for South American observers just before & after sunset.

The occultation of Venus by the Moon; the footprint over South America. (Credit: Occult 4.1.0.2).

We witnessed and recorded a similar pairing of Venus and the daytime Moon from the shores of our camp on Saint Froid Lake in northern Maine back in 2007:

Also, keep an eye out for a ghostly phenomenon known as the ashen light on the dark limb of the Moon. Also known as Earthshine, what you’re seeing is the reflection of sunlight off of the Earth illuminating the (cue Pink Floyd) dark side of the Moon. When the Moon is a crescent as seen from the Earth, the Earth is at gibbous phase as seen from the nearside of the Moon. Remember, the lunar farside and darkside are two different things! Earthshine can vary in brightness, based on the amount of cloud and snow cover present or absent on the Earth’s moonward side. My Farmer’s Almanac-consulting grandpappy would call ashen light the “Old Moon in the New Moon’s arms,” and reckon rain was a comin’…

Be sure to check out these astronomical goings on this weekend, and send those pics in to Universe Today!

July 8, 2013April 26, 2016 by David Dickinson

Conjunctions to Watch For in July

The waxing crescent Moon joins the evening sky early this week. (Photo by author).

The planets are slowly returning into view this month, bashfully peeking out from behind the Sun in the dawn & dusk sky. This month offers a bonanza of photogenic conjunctions, involving the Moon, planets and bright stars.

The action begins tonight on July 8^th, as the waxing crescent Moon joins the planet Venus in the dusk sky. The razor thin Moon will be a challenge on Monday night, as it just passed New on the morning of the 8^th at 3:14AM EDT/7:14 Universal Time (UT). The record for spotting the thin crescent with the naked eye currently stands at 15 hours and 32 minutes, completed by Stephen O’Meara on May 1990. Binoculars help considerably in this endeavor. Wait until 15 minutes after local sunset, and then begin patiently sweeping the horizon.

Mr. Thierry Legault completed an ultimate photographic challenge earlier today, capturing the Moon at the precise moment of New phase!

The Moon & Venus on the evening of July 9th from latitude 30 degrees north, about 30 minutes after sunset. (Created by the author using Stellarium). — The Moon & Venus on the evening of July 9th as seen from latitude 30 degrees north, about 30 minutes after sunset. (Created by the author using Stellarium).

This week marks the start of lunation 1120. The Moon will be much easier to nab for observers worldwide on Tuesday night, July 9^th for observers worldwide. The sighting of the waxing crescent Moon will also mark the start of the Muslim month of Ramadan for 2013. Due to the angle of the ecliptic in July, many northern hemisphere observers may not spot the Moon until Wednesday night on July 10^th, about 6.7 degrees south west of -4.0 magnitude Venus.

Did you know? There are Guidelines for the Performance of Islamic Rites for Muslims aboard the International Space Station. It’s interesting to note that the timing of the rituals follows the point from which the astronaut originally embarked from the Earth, which is exclusively the Baikonur Cosmodrome in Kazakhstan for the foreseeable future of manned spaceflight.

Malaysia’s first astronaut, Sheikh Muszaphar Shukor observed Ramadan aboard the International Space Station in 2007.

From there, the crescent Moon fattens, meeting up with Saturn and Spica on the evenings of July 15^th and 16^th. The Moon will actually occult (pass in front of) the bright star Spica on the evening of July 15/16^th at ~3:33UT/11:33PM EDT (on the 15^th) for observers in Central America and western South America. The rest of us will see a near miss worldwide.

The waxing crescent Moon nearing Spica on the evening of the 15th at 10PM EDT. The Moon reaches 1st Quarter on the same evening at 11:18PM EDT. (Created by the author using Starry Night). — The waxing crescent Moon nearing Spica on the evening of the 15th at 10PM EDT. The Moon reaches 1st Quarter phase on the same evening at 11:18PM EDT. (Created by the author using Starry Night).

This is the 13th in a cycle of 18 occultations of Spica by our Moon spanning 2012-2013. Spica is one of four stars brighter than magnitude +1.4 that lie close enough to the ecliptic to be occulted by our Moon, the others being Antares, Regulus and Aldebaran. Saturn will lie 3 degrees from the Moon on the evening of July 16^th.

Can you nab Spica and Saturn near the Moon with binoculars in the daytime around the 15^th? It can be done, using the afternoon daytime Moon as a guide. Crystal clear skies (a rarity in the northern hemisphere summertime, I know) and physically blocking the Sun behind a building or hill helps.

The waxing gibbous Moon will also occult +2.8 Alpha Librae for South Africa on July 17^th around 17:09UT & +4.4^th magnitude Xi Ophiuchi for much of North America on the night of July 19^th-20^th.

And speaking of Regulus, the brightest star in the constellation Leo lies only a little over a degree (two Full Moon diameters) from Venus only the evenings of July 21^st & the 22^nd. 77.5 light years distant, Regulus is currently over 100 times fainter at magnitude +1.4. Can you squeeze both into the field of view of your telescope at low power? Venus’s mythical ‘moon’ Neith lives!

Venus can even occult Regulus on rare occasions, as last occurred on July 7th, 1959 and will happen next on October 1st, 2044.

But there’s morning action afoot as well. The planets Mars and Jupiter have emerged from solar conjunction on April 18th and June 19th, 2013 respectively, and can now be seen low in the dawn skies about 30 minutes before sunrise.

Mars and Jupiter in a close conjunction on the morning of July 22nd, about 30 minutes before sunrise as seen from latitude 30 degrees north. (Created by the author using Starry Night).

Mars approaches Jupiter in the dawn until the pair is only 0.79 degrees (about 48 arc minutes) apart on Monday, July 22^nd. Mars shines at magnitude +1.6 and shows a tiny 3.9” disk, while Jupiter displays a 32.5” disk shining at magnitude -1.9 on this date. Conjunction occurs at about 7:00 UT/3:00 AM EDT, after which the two will begin to race apart. Mercury is visible beginning its morning apparition over 5 degrees to the lower right of the pair (see above).

Jupiter will reach opposition and reenter the evening sky on January 5th, 2014, while Mars won’t do the same until April 8th of next year. Weird factoid alert: neither Jupiter or Mars reach opposition in 2013! What effect does this have on terrestrial affairs? Absolutely none, well unless you’re a planetary imager/observer…

Mars also reaches its most northern declination of 2013 of 24 degrees in the constellation Gemini on July 16^th at 7:00 AM EDT/11:00 UT. Mars can wander as far as declination 27 degrees north, as last happened in 1993.

Finally, are you observing from southern Mexico this week and up for a true challenge? The asteroid 238 Hypatia occults a +7.4 magnitude star from 10:13-10:49 UT on July 10^th in the constellation Pisces for up to 29 seconds. This event will be bright enough to watch with binoculars- check out our best prospects for asteroid occultations of stars in 2013 here and here.

Good luck, clear skies, and be sure to post those astro-pics in the Universe Today’s Flickr community!