Bob King, Author at Universe Today

January 2, 2014December 23, 2015 by Bob King

Comets Prospects for 2014: A Look Into the Crystal Ball

Comet C/2013 R1 Lovejoy starts the new year as the brightest comet in the sky at around magnitude 6. In this photo taken on Dec. 31, two tails are visible. The longer one is the ion or gas tail; the broader fan is the dust tail. Credit: Damian Peach

As 2014 opens, most of the half dozen comets traversing the morning and evening sky are faint and require detailed charts and a good-sized telescope to see and appreciate. Except for Comet Lovejoy. This gift to beginner and amateur astronomers alike keeps on giving. But wait, there’s more. Three additional binocular-bright comets will keep us busy starting this spring.

Track of Comet C/2013 R1 Lovejoy in the morning sky marked at 3-day intervals shortly before the start of dawn (6 a.m. local time) tomorrow through Jan. 31. Stars shown for Dec. 29 to magnitude 5.8. Her = Hercules and Oph = Ophiuchus. Click to enlarge. Created with Chris Marriott's SkyMap software — Track of Comet C/2013 R1 Lovejoy in the morning sky marked at 3-day intervals shortly before the start of dawn (6 a.m. local time) tomorrow through Jan. 31. Stars shown for Dec. 29 to magnitude 5.8. Her = Hercules and Oph = Ophiuchus. Click to enlarge. Created with Chris Marriott’s SkyMap software

Still glowing around the naked eye limit at magnitude 6, the Lovejoy remains easy to see in binoculars from dark skies as it tracks from southern Hercules into Ophiuchus in the coming weeks.

The best time to view the comet is shortly before the start of dawn when it sails highest in the eastern sky at an altitude of around 30 degrees or “three fists” up from the horizon. By January’s end, the comet will still be 25 degrees high in a dark sky. My last encounter with Lovejoy was a week ago when 10×50 binoculars revealed a bright coma and 1.5 degree long tail to the northwest. Through the telescope the stark contrast between bright, compact nucleus and gauzy coma struck me as one of the most beautiful sights I’d seen all month.

Path of Comet C/2012 K1 PANSTARRS this spring when it should be a nice comet for small to medium sized telescopes. Created with Chris Marriott's SkyMap software — Path of Comet C/2012 K1 PANSTARRS this spring when it should be a nice comet for small to medium sized telescopes. Created with Chris Marriott’s SkyMap software

Looking ahead to 2014 there are at present three comets beside Lovejoy that are expected to wax bright enough to see in binoculars and possibly with the naked eye: C/2012 K1 PanSTARRS, C/2013 V5 Oukaimeden and C/2013 A1 Siding Spring The first lurks in Hercules but come early April should bulk up to magnitude 9.5, bright enough to track in a small telescope for northern hemisphere observers. Watch K1 PANSTARRS amble from Bootes across the Big Dipper and down through Leo from mid-spring through late June hitting magnitude 7.5 before disappearing in the summer twilight glow. K1 will be your go-to comet during convenient viewing hours.

Come early September after K1 PANSTARRS leaves the sun’s ken, it reappears in the morning sky, traveling westward from Hydra into Puppis. Southern hemisphere observers are now favored, but northerners won’t suffer too badly. The comet is expected to crest to magnitude 5.5 in mid-October just before it dips too far south for easy viewing at mid-northern latitudes.

Comet Oukaimeden may glow around 8th magnitude in late August 2014 when it rises with the winter stars before dawn. Stellarium.

Comet C/2013 V5 (Oukaimeden), discovered November 15 at Oukaimeden Observatory in Marrekesh, Morocco. Preliminary estimates place the comet at around magnitude 5.5 in mid-September. It should reach binocular visibility in late August in Monoceros the Unicorn east of Orion in the pre-dawn sky before disappearing in the twilight glow for mid-northern latitude observers. Southern hemisphere skywatchers will see the comet at its best and brightest before dawn in early September and at dusk later that month.

Comet C/2013 A1 Siding Spring is currently a faint 14th magnitude object in Eridanus. Photo taken on Dec. 30, 2013. Credit: Rolando Ligustri

2014’s most anticipated comet has to be C/2013 A1 Siding Spring, expected to reach magnitude 7.5 and become binocular-worthy for southern hemisphere skywatchers as it traverses the southern circumpolar constellations this September. Northerners will have to wait until early October for the comet to climb into the evening sky by way of Scorpius and Sagittarius. Watch for an 8th magnitude hazy glow in the southwestern sky at that time.

As October ticks by, A1 Siding Spring creeps closer and closer to Mars until it overlaps the planet on the 19th. Normally, a comet will only appear to pass in front of stars and deep sky objects because it’s in the same line of sight. Not this time. Siding Spring may actually “touch” Mars for real.

Comet C/2013 A1 Siding Spring will overlap Mars on October 19, 2014. With the planet at magnitude — Comet C/2013 A1 Siding Spring will overlap Mars on October 19, 2014. Assuming magnitude 8 at the time, the comet should look like a hazy glow around the planet through binoculars and telescopes. Stellarium

On October 19 the comet will pass so close to the planet that its outer coma or atmosphere may envelop Mars and spark a meteor shower. The sight of a bright planet smack in the middle of a comet’s head should be something quite wonderful to see through a telescope.

While the list of predicted comets is skimpy and arguably not bright in the sense of headliners like Hale-Bopp in 1997 or even L4 PANSTARRS from last spring, all should be visible in binoculars from a dark sky site.

Every year new comets are discovered, some of which can swiftly brighten and put on a great show like Comet Lovejoy (discovered Sept. 7) did last fall and continues to do. In 2013, 64 new comets were found, 14 of them by amateur astronomers. Comets with the potential to make us ooh and aah are out there – we just have to find them.

January 1, 2014December 23, 2015 by Bob King

See the Youngest Moon of Your Life Tonight

A 24-hour-old moon photographed from Duluth, Minn. U.S. on in May 2010. Credit: Bob King

The new year starts out with a bang, offering the chance to spy an exceptionally thin crescent moon shortly after sunset. Here’s how to find it.

The moon’s age is determined by how many hours or days have passed since new moon phase. New moon occurs once a month when the moon lies in nearly the same direction as the sun in the sky. No one can see a new moon because it stays very close to the sun and lost in the glare of daylight.

To attempt your personal youngest moon yet, find a flat horizon to the southwest and start looking about 10 minutes after sunset. This panel shows the sky from four different locations. The times shown are 20 minute after local sunset and the moon's elevation at those times is also noted. Created with Stellarium — To attempt your personal youngest moon yet, find a flat horizon to the southwest and start looking about 10 minutes after sunset. This panel shows the sky from four different locations. The times and moon’s elevation are shown for 20 minutes after local sunset. The moon’s orientation is approximate. Created with Stellarium

Under favorable circumstances it isn’t too difficult to spot a 1-day-old moon, referred to as a young moon because it’s the first or youngest bit of moon we see after new moon. Young moons are delicate and tucked far down in the twilight glow shortly after sunset. Spotting one fewer than 24 hours old requires planning. You need a flat horizon, haze-free skies and a pair of binoculars. Being on time’s important, too. Be sure to arrive at your observing spot shortly before sundown. Knowing the point on the horizon where the sun sets will guide you to the crescent’s location.

An 18-hour-old crescent moon photographed in a 12-inch telescope on April 22, 2012. Credit and copyright: John Chumack and Maurice Massey

Ready to rock and roll? New moon occurred at 5:14 a.m. (CST) today. For the U.S. Midwest that makes the moon approximately 12 hours old at sunset this evening. Since the moon moves to the east or away from the sun at the rate of one moon-diameter per hour, skywatchers in the western U.S. will have it somewhat easier shot at seeing it. In Denver, the moon will be 13 hours old, while in San Francisco it will have aged to 14 hours. Hawaii residents will have their shot at a 16-hour-old moon, still very young but farther yet from the sun and easier to see. To know exactly when the sun and moon set for your city, click HERE.

Luckily you’ll have more than just the sunset point to help know in which direction to look; Venus, itself a very thin crescent moon at the moment, hovers 7-8 degrees to the upper left of the moon. You should have no problem seeing a crescent Venus in binoculars.

The record for youngest moon spotted with the naked eye goes to writer and amateur astronomer Steven James O’Meara, who nabbed a 15 hour 32 minute crescent in May 1990. The skinniest moon ever seen with optical aid goes to Mohsen G. Mirsaeed of Tehran on September 7, 2002 at just 11 hours 40 minutes past new.

Venus, seen here several years back to the lower right of the moon along with Jupiter, will not only help with focus tonight but will guide toward the thin crescent. Credit: Bob King — Venus, seen here several years back to the lower right of the moon along with Jupiter, will not only help with focusing tonight but will guide skywatchers toward the thin crescent. Credit: Bob King

Based on these facts, it’s likely few will see the faint arc of moon with the naked eye especially in the eastern U.S. where the crescent will be only 11 hours old. Binoculars and telescopes will be required for most of us. To meet tonight’s challenge, make sure your binoculars are focused at infinity before you start. Again, Venus comes to our aid. Carefully focus the planet until you see its crescent as sharply as possible. You can also focus on any clouds that might be present. Lacking that, aim for the most distant object in the landscape. Focus is critical. If you’re off, the thin moon will soften, spread out and appear even fainter.

I couldn't resist adding this pic of the waning moon taken by one of the International Space Station astronauts as it rose over the limb of the Earth. Credit: NASA — I couldn’t resist adding this fine photo of the waning moon taken by one of the International Space Station astronauts as it rose over the limb of the Earth. Credit: NASA

Start looking for the moon about 10 minutes after sundown in nearly the same direction as the sunset point within a strip of sky as wide as a typical binocular field of view or about 5 degrees. Slowly scan up and down and back and forth over the next 25 minutes looking for a wispy sliver of light against the deepening blue sky. Should you find the moon, you might be surprised at the broken appearance of the arc. These seeming breaks are caused by oblique lighting on crater walls and mountain peaks creating shadows long enough to bite into and hide portions of the moon’s sunlit edge.

I wish you the best in your search tonight for what could be one of the rarest astronomical sightings of your life. It won’t be easy. Whether you succeed or not, please drop us a comment and share your story.

December 30, 2013December 23, 2015 by Bob King

Jan. 16 May Be Last Best Chance to Search for Comet ISON’s Remains

Comet ISON revolves around the sun in steeply inclined orbit. Earth will pass through the plane of that orbit on Jan. 16. As we look "up" toward the comet our edgewise perspective could cause a temporary brightening of ISON's dust remnant. Credit: solarsystemscope.com with annotations by the writer.

Is there any hope of detecting what’s left of Comet ISON after the sun proved too much for its delicate constitution? German amateur astronomer Uwe Pilz suggest there remains a possibility that a photographic search might turn up a vestige of the comet when Earth crosses its orbital plane on January 16, 2014.

Update: See an image below taken by Hisayoshi Kato of the comet’s location in Draco on December 29!

Comet ISON is located high in the northern sky near the familiar "W" or "M" or Cassiopeia during the time of orbital crossing. Stellarium — Comet ISON is located high in the northern sky near the familiar “W” or “M” or Cassiopeia during the time of orbital crossing. Stellarium

On and around that date, we’ll be staring straight across the sheet of debris left in the comet’s path. Whatever bits of dust and grit it left behind will be “visually compressed” and perhaps detectable in time exposure photos using wide-field telescopes. To understand why ISON would appear brighter, consider the bright band of the Milky Way. It stands apart from the helter-skelter scatter of stars for the same reason; when we look in its direction, we peer into the galaxy’s flattened disk where the stars are most concentrated. They stack up to create a brighter band slicing across the sky. Similarly, dust shed by Comet ISON will be “stacked up” from Earth’s perspective on the 16th.

Comet L4 PanSTARRS bizarre beam-like appearance on May 28 near the time of orbital plane crossing. Credit: Michael Jaeger — Comet L4 PanSTARRS beam-like appearance on May 28 near the time of orbital plane crossing. Credit: Michael Jaeger

This isn’t the first time a comet has leapt in brightness at an orbital plane crossing. You might recall that Comet C/2011 L4 PanSTARRS temporarily brightened and assumed a striking linear shape when Earth passed through its orbital plane on May 27.

Comet ISON debris simulations for Jan. 12 and 14, 2014. Credit: Uwe Pilz — Comet ISON debris simulations for Jan. 12 and 14, 2014. The aqua line points toward the sun; the black line is 1 degree long. Credit: Uwe Pilz

Pilz, a longtime contributor to the online Comets Mailing List for dedicated comet observers, has made a series of simulations of Comet ISON for mid-January using his own comet tail program. He bases his calculations on presumed larger particle sizes 1 mm – 10 mm – not the more common 0.3-10 micrometer fragments normally shed by comets. The assumption here is that ISON has remained virtually invisible since perihelion because it broke up into a smaller number of larger-than-usual pieces that don’t reflect light nearly as efficiently as larger amounts of smaller dust particles.

A slivery ISON on Jan. 16 widens a bit two days later in Pilz's simulations. Credit: Uwe Pilz — A slivery ISON on Jan. 16 widens a bit two days later in Pilz’s simulations. Click to see additional simulations. Credit: Uwe Pilz

The images look bizarre at first glance but totally make sense given the unique perspective. Notice that the debris stream becomes thinner as we approach orbital crossing; any potential dust blobs appear exactly edge-on similar to the way Saturn’s rings narrow to a “line” when Earth passes through the ring plane.

Besides the fact that not a single Earth-bound telescope has succeeded to date in photographing any of ISON’s debris, amateurs who attempt to fire one last volley the comet’s way will face one additional barrier – the moon. A full moon the same day as orbital crossing will make a difficult task that much more challenging. Digital photography can get around moonlight in many circumstances, but when it comes to the faintest of the faint, the last thing you want in your sky is the high-riding January moon. One night past full, a narrow window of darkness opens up and widens with each passing night.

Will anyone take up the challenge?

UPDATE Dec. 30 10 a.m. (CST): We may have our very first photo of Comet ISON from the ground! Astrophotographer Hisayoshi Kato made a deep image of the comet’s location in Draco on December 29 using a 180mm f/2.8 telephoto lens near the Mauna Loa Observatory in Hawaii at 11,000 feet. He stacked 5 exposures totaling 110 minutes to record what could be the ISON’s debris cloud. It’s incredibly diffuse and faint and about the same brightness as the Integrated Flux Nebula, dust clouds threading the galaxy that glow not by the light of a nearby star(s) but instead from the integrated flux of all the stars in the Milky Way. We’re talking as dim as it gets. What the photo recorded is only a tentative identification – followup observations are planned to confirm whether the object is real or an artifact from image processing. Stay tuned.

The sausage-like glow running from upper left to lower right in this negative image may the dusty remains of Comet ISON as photographed on Dec. 29 from Hawaii. Click to enlarge. Credit: Hisayoshi Kato — The sausage-like glow running from upper left to lower right in this negative image may the dusty remains of Comet ISON as photographed on Dec. 29 from Hawaii. The blue dot shows the predicted position of the comet; the green type gives the names of stars. Click to enlarge. Credit: Hisayoshi Kato

December 27, 2013December 23, 2015 by Bob King

Venus Slip-Slides Away – Catch it While You Can!

Venus reflected in the Pacific Ocean late this fall seen from the island of Maui, Hawaii. The planet is now quickly dropping toward the sun. Credit: Bob King

I put down down the snow shovel to give my back a rest yesterday evening and couldn’t believe what I saw. Or didn’t see. Where was Venus? I looked to the south above the tree line and the goddess was gone! Sweeping my gaze to the right I found her again much closer to the western horizon point and also much lower.

As Venus revolves around the sun interior to the Earth's orbit, we see it pass through phases just like the moon. Tonight it's still to the east of the sun (left side) and visible in the evening sky. On Jan. 11 it passes through conjunction and then appears on the other side of the sun in the morning sky. Illustration: Bob King — As Venus revolves around the sun interior to Earth’s orbit, we see it pass through phases just like the moon. Tonight it’s still to the east of the sun (left side) and visible in the evening sky. On Jan. 11 it passes through conjunction and then appears on the other side of the sun in the morning sky. Illustration: Bob King

As 2013 gives way to the new year, Venus winds up its evening presentation as it prepares to transition to the morning sky. Catch it while you can. Each passing night sees the planet dropping ever closer to the horizon as its apparent distance from the sun shrinks. On January 11 it will pass through inferior conjunction as it glides between Earth and sun. Come the 12th, Venus nudges into the dawn sky – don’t expect to see it with the naked eye until around midmonth, when it’s far enough from the sun to bust through the twilight glare.

Phases of Venus during 2004 photographed through a telescope. When very close to inferior conjunction (bottom right) the crescent is seen to extend fully around the planet. Credit: Statis Kalyva / Wikipedia

Though the planet is departing, don’t let it disappear without at least a glance through binoculars. As conjunction approaches, Venus gets as close (and as large) as it can get to Earth and displays a most attractive crescent phase. Even 7x binoculars will show its thinning sickle shortly at dusk. Tonight (Dec. 27) Venus measures nearly 1 arc minute in diameter or 1/30 the width of the full moon and shines brightly at magnitude -4.5.

Venus is only about 12 degrees high in the southwestern sky some 20 minutes after sunset this evening Dec. 27. Stellarium

As the planet drops ever lower, the crescent grows both larger and thinner. A few days before conjunction, a telescope will show it extending beyond the usual 180-degree arc as sunlight beaming from behind Venus is scattered by the planet’s thick cloudy atmosphere.

When the air is transparent and seeing steady, amateur astronomers have photographed and observed the crescent wrapping a full 360 degrees around the planet’s disk – a sight quite unlike anything else in the sky.

Before Venus departs the evening sky watch for it to pair up with a very thin crescent moon shortly after sunset on Jan. 2, 2014. Stellarium — Before Venus departs the evening sky, watch for it to pair up with a very thin crescent moon shortly after sunset on Jan. 2, 2014. Stellarium

In the coming week, watch for Venus starting about 15 minutes after sunset low in the southwestern sky. With each day, the planet becomes slightly less conspicuous as it competes against the twilight glow.

After final farewells late next week, we’ll look forward in the new year to welcoming the goddess in her new guise as morning star.

December 20, 2013December 23, 2015 by Bob King

Hubble Looks but Finds No Trace of Comet ISON

Each of the four panels is a combination of two separate exposures made by the Hubble Space Telescope as it tracked Comet ISON's position. Had the comet been in any of these frames, it would have appeared as a small fuzzy glow or stellar point(s) in the center. The stars are trailed because the camera tracked the comet. Credit: NASA/ESA

On December 18, the Hubble Space Telescope slewed to Comet ISON’s expected position and found nothing down to the incredibly faint magnitude of 25. According to astronomer Hal Weaver, who planned the ISON search, that limit implies any remaining fragments would have to be smaller than about 500 feet (160 meters) in diameter.

Composite photo of one of two Comet ISON locations photographed by the Hubble in a way that suppresses features not in the same place. No trace of the comet is visible. Credit: NASA/ESA — Composite photo of one of two Comet ISON locations photographed by the Hubble Space Telescope. No trace of the comet is visible. Credit: NASA/ESA

Nothing is visible in any of the images in the photo panel except trailed stars and galaxies, reflections and the occasional zap of a cosmic ray. After ISON was torn asunder by the sun, there existed the possibility that comet’s remains would follow a slightly different orbit. To make sure he was covered, Weaver photographed two separate comet positions, stacking several exposures together.

Comet ISON photographed at a second location. Again, nothing detected. Credit: NASA/ESA

“The images have been combined so that features not at the same place in the various images are suppressed. Any comet fragments would show up more clearly in this composite, though stars still show up as faint streaks”, writes Zolt Lavay, author of the ISONblog at the Hubble site.

Again, nothing shows up in these either. While no one can say that ISON has completely disappeared, we now know that at the very least it’s broken into pieces too small for even Hubble to see. What was once a beautiful sight in binoculars has expanded into a vast cloud of gas and dust thinner than Ebenezer Scrooge’s gruel.

December 19, 2013December 23, 2015 by Bob King

Visions of Earth through the Yutu Rover’s Eyes

Earth eclipses the sun from Chang'e 3's location in the Sea of Rains on April 15, 2014. At the same time, we'll see a total lunar eclipse from the ground. Stellarium

Last night I used my telescope to eye-hike the volcanic plains of the Sea of Rains (Mare Imbrium) where the Yutu rover and lander sit beneath a blistering sun. With no atmosphere to speak of and days that last two weeks, noontime temperatures can hit 250 degrees Fahrenheit (122 C) . That’s hot enough that mission control at the Beijing Aerospace Command and Control Center has decided to draw the shades and give the rover a nap from science duties until December 23 when things cool down a bit.

While studying the subtle gray hues of the Imbrium lava flows I got to wondering what the sky might look like if I could don a spacesuit and visit the landing site “where the skies are not cloudy all day” (to quote a famous song). With no atmosphere to speak of, stargazing can be done both day and night on the moon though I suspect it’s better at night when there’s less glare from your surroundings. Night, defined as the time from sunset to sunrise (no twilights here), lasts about 14.5 Earth days. Days are equally long.

Lunar landscape photographed by the Chang'e 3 lander on Dec. 15, 2013. Credit: CCTV — Lunar landscape photographed by the Chang’e 3 lander on Dec. 15, 2013. Credit: CCTV

From Yutu’s point of view, it’s very nearly lunar noon today (Dec. 19) with the sun halfway up in the southern sky. Looking at the map of the sky from the lander’s location, you’ll see a few familiar constellations and one very familiar planet – Earth!

Phases of the moon and Earth are complementary. When the moon is full, Earth's a crescent. This map shows the Earth in Capricornus on Dec. 20 as thin blue crescent. Stellarium — Phases of the moon and Earth are complementary. When the moon is full, Earth’s a crescent. This map shows the Earth in Capricornus on Dec. 20 as thin blue crescent. Stellarium

Today Earth appears as a very thin crescent a short distance to the left or east of the sun. Because the moon takes just as long to rotate on its axis as it does to revolve around the Earth, the same face of the moon always faces our planet. Because the two are in synchrony, astronomers call it synchronous rotation.

From the perspective of someone standing on the moon, Earth stands still in one spot of sky throughout the 29.5 day lunar day-night cycle. Well, not perfectly still. Because the moon’s orbit is inclined about 5 degrees to Earth’s orbit and its speed varies along its non-circular orbit, Earth describes a little circle in the lunar sky about 10 degrees in diameter every four weeks.

As the sun slowly moves off to the west, our blue planet remains nearly stationary from Yutu’s perspective and undergoes all the familiar phases we see the moon experience back here on Earth: an evening crescent to start followed by a first quarter Earth, Full Earth last quarter and finally, New Earth. I like the ring of that last one.

The lunar landscape at the rover's location is bathed in pale blue light on Dec. 31, 2013 during "Full Earth". Stellarium — The lunar landscape at the rover’s location is bathed in pale blue light on Dec. 31, 2013 during a Full Earth. Stellarium

Yutu and the lander will see the sun drift to the west while Earth moves east, rises higher in the lunar sky and putting on the pounds phase-wise. Today Earth’s glides across the border of Sagittarius into Capricornus. The next Full Earth happens on New Year’s Eve when the sun is directly opposite the Earth in the lunar sky.

Full Earth always happens around local midnight or about one week before sunrise during the long lunar day. On the moon the sun is up for about two weeks and then disappears below the horizon for another two weeks before rising again. At Full Earth time, the sun remains hidden around the lunar backside. When the nights are blackest, the bright ball of Earth spreads a welcome blue glow over the desolate landscape.

Earth covering the sun with a flash of the "diamond ring effect" just before total solar eclipse on April 15 and Oct. 8 next year. Stellarium — Simulated eclipse of the sun by the Earth just before totality on April 15 and Oct. 8 next year. On both dates, we’ll see a total lunar eclipse from the ground. Stellarium

Things really get interesting during lunar eclipses when the moon moves behind the Earth into the planet’s shadow. The next one’s on April 15, 2014. Here on the ground we’ll see the moon gradually munched into by Earth’s shadow until totality, when sunlight from all the sunrises and sunsets around the rim of the planet are refracted by the atmosphere into the shadow, coloring the moon a coppery red.

Two pictures of the ring of sunset-sunrise fire around the Earth as it totally eclipsed the sun from the moon. Credit: NASA

Yutu will see just the opposite. Looking back toward the Earth from inside its shadow, the rover will witness a total eclipse of the sun by the Earth. If by some wonder the Chinese are able to photograph the event, we’ll see photos of the black ball of Earth rimmed in red fire from sunset and sunrise light refracted by our atmosphere. My interpretation using sky mapping software only hints at the wonder of the scene. Beijing Aerospace, if you’re reading this, please make it happen.

Earth eclipses the sun filmed by Japan’s Kaguya lunar orbiter. There are really two eclipses here – the Earth eclipsed by the limb of the moon at the video’s start followed by the solar eclipse.

On two other occasions, our robotic emissaries have photographed solar eclipses from Luna. NASA’s Surveyor 3 snapped a couple crude pictures of the April 24, 1967 eclipse from inside a crater in Mare Cognitium, the Sea that has Become Known. Japan’s orbiting Kaguya probe did the job much more eloquently on video during the February 9, 2009 penumbral lunar eclipse. In a penumbral eclipse (seen from Earth) the moon misses Earth’s dark inner shadow called the umbra, passing only through the outer penumbra, but because the Earth is three times larger than the sun (seen from the moon), it easily covered the sun completely in the complementary total solar eclipse.

And the best thing about watching eclipses from the moon? Guaranteed clear skies!

December 18, 2013December 23, 2015 by Bob King

Smack! A New Crater Appears on the Moon/ Yutu Rover Update

Before and after views of the March 17, 2013 impact taken by the LRO camera. Credit: NASA/GSFC/Arizona State University

Where there’s smoke, there’s fire, or in this instance, a new hole in the moon. NASA’s Lunar Impact Monitoring Program recorded the brightest meteoroid impact ever in its 8-year history on March 17 this year. The flash of light, as luminous as a 4th magnitude star and lasting about one second, was caught on video striking the moon in the Sea of Rains (Mare Imbrium) not far from the prominent crater Copernicus. Some time after the event, the Lunar Reconnaissance Orbiter (LRO) swept in for a closer look and spied a brand new impact crater.

Since 2005 the program has detected over 300 flashes which are presumed to be from meteoroid impacts.

Bright impact flash made by a foot-wide rock that struck the moon on March 17, 2013. The moon was a crescent in the evening sky at the time. The impact occurred in the dark, earthlit part of the moon away from the sun-lit crescent. Click photo to see video about the event. Credit: NASA

Based on the flash brightness and duration of the St. Pat’s Day smack, the space boulder measured between one to 1.5 feet long (0.3-0.4 meters) and struck the moon traveling at 56,000 mph with a force of 5 tons of TNT. Scientists predicted then that the impact could produce a crater up to 65 feet (20 meters) in diameter.

Left: Fresh material brought to the surface makes the new 59-foot-wide crater look like it was spray painted white. Credit: NASA/GSFC/Arizona State University. Right: The meteoroid strike occurred near the prominent crater Copernicus in Mare Imbrium. Credit: Bob King — Left: Fresh material brought to the surface makes the new 59-foot-wide crater look like it was spray painted white. Credit: NASA/GSFC/Arizona State University. Right: The meteoroid strike occurred near the familiar crater Copernicus in the Sea of Rains (Mare Imbrium). Credit: Bob King

Well, guess what? When LRO dropped by for a look and compared images taken of the flash site before and after March 17. Staring it in the face was a brand new crater 59 feet across (18 meters). Wow! Just look at how reflective the crater and its rays of ejecta appear. That’s all unweathered, fresh dust and rock excavated from beneath the surface courtesy of 5 tons of extraterrestrial TNT. While impressive from LRO’s 31-mile altitude, the “St. Pat” crater is unfortunately invisible in even the largest telescopes from Earth.

Over time, cosmic rays, solar irradiation and micrometeoroids darken and redden the lunar soil. Millions of years from now, the once brilliant crater will blend into the moonscape. Can you imagine how bright larger craters like Tycho and Copernicus must have looked once upon a time?

Now it's the Chinese Yutu rover's turn to take a photo of the lander. Credit: CCTV — Now it’s the Chinese Yutu rover’s turn to take a photo of the lander. Credit: CCTV

The March 17 impact wasn’t the first new crater seen by LRO, but it does appear to be one of the largest. The LRO camera team has been systematically searching its archive of before and after images for many more lunar landscape changes. Some of those results – including these photos – were presented at the American Geophysical Union Fall Meeting last week; more new craters will be announced in the near future.

Left: The lander's new location in northern Mare Imbrium. Right: LRO scientists have so far nailed down the lander's position somewhere inside the red box on the rim of a small crater with exposed rocky outcrops. Picture is about 1,750 feet side to side. Credit: NASA — Left: The lander’s new location in northern Mare Imbrium. Right: LRO scientists have so far nailed down the lander’s position somewhere inside the red box on the rim of a small crater with exposed rocky outcrops. Picture is about 1,750 feet side to side. Credit: NASA

While we’re on the topic of flyover discoveries, NASA will photograph the Chinese Yutu rover and lander when LRO orbits over western Mare Imbrium on Dec. 24 and 25. As it turns out, the lander didn’t land in Sinus Iridium as reported earlier but in nearby Mare Imbrium, a good distance east of the original site but still within the official “landing box”.

Fortuitously, this location turns out to be a great spot to examine young lavas not sampled during the Apollo missions. All the Apollo rocks ranged in age from 3.1 to 3.8 billion years old. Based on crater counts and the flow’s relatively fresh appearance, Yutu sits at the northern edge of a lava sheet dated at between 1 and 2.5 billion years. In lunar years, that’s fresh!

Flow lobes in the lavas of Mare Imbrium. Chang’e 3 landed at the extreme northern end of this sequence of lavas, which are very young in lunar terms. Credit: NASA / Apollo 15

Younger flows experience less erosion, so the lunar bedrock isn’t buried beneath as much rock as at the Apollo sites. Where Yutu sits, the lunar soil or regolith goes down some 6-7 feet (2 meters) instead of 10-26 feet (3-8 meters) at other landing sites. That means easier excavation of much sought after lunar bedrock. We may even be seeing blocks of bedrock littered about the ~35 foot wide crater (10 meters) in one of the first photos sent back to Earth by the Chinese lander.

The boulders strewn about the crater rim at the Chang'e 3 landing site might be samples of lunar bedrock. Credit: CCTV — The boulders strewn about the crater rim at the Chang’e 3 landing site might be samples of lunar bedrock. Credit: CCTV

For a great analysis of the Chang’e 3 landing site, I recommend reading A New Site to Explore on the Moon by lunar geologist Paul D. Spudis

November 25, 2013December 23, 2015 by Bob King

Guide to Safely Viewing Comet ISON on Perihelion Day, November 28

Comet ISON joins Earth and Mercury in this photo made by NASA's STEREO-A (Ahead) spacecraft in the early morning hours of Nov. 23, 2013. Click to see additional images.

The day of truth is fast approaching. Will Comet ISON’s sungrazing ways spark it to brilliance or break it to bits? How bright will the comet become? Studying the latest images from NASA’s STEREO Ahead sun-watching spacecraft, it’s obvious that ISON remains healthy and intact. The most recent pictures taken from the ground confirm that no major breakup has occurred. Assuming that ISON doesn’t crumble apart on Nov. 28, when it passes just 730,000 miles (1.2 million km) from the sun, it could brighten to -4 magnitude or better in the hours leading up to and after the moment of perihelion at 12:24:57 p.m. CST (18:24:57 UT).

This beautiful photo of Comet ISON was taken from a mountaintop observatory with a 300mm lens by Juan Carlos Casado of Spain on Nov. 24, 2013. Casado “stacked” or composited four photos to enhance the brightness of the comet against twilight. Click to enlarge.

For comparison, the planet Venus hovers around -4 magnitude and is routinely visible visible with the naked eye in broad daylight if you know exactly where to look. For the sake of establishing a baseline, let’s imagine that ISON will match Venus in magnitude during its crack-the-whip fling around the sun. Naturally, this would put the comet within range of naked eye visibility smack in the middle of the day. Well, maybe. ISON presents us with a little problem. While it may grow bright enough to view in daylight, it will be very close to the sun on perihelion day. Not only will it be difficult to tease from the solar glare, but with the sun only a degree or two away, there’s a real danger you could damage your eyes if you stray too close.

Comet ISON swings rapidly around the sun on perihelion day Nov. 28. Times shown are CST with north up and west to the right. Created with Chris Marriott's SkyMap software — Comet ISON swings rapidly around the sun on perihelion day Nov. 28. Positions are shown hourly with north up and west to the right. Created with Chris Marriott’s SkyMap software

During the early morning hours of the 28th, ISON will lie approximately 2.5 degrees from the sun’s limb or edge. At the time of perihelion that separation narrows to less than 1/2 degree or one solar diameter. This is likely when the comet will shine brightest, but with the sun so close, it will be next to impossible to spot it with naked eye or binoculars at that time. Matter of fact, don’t even try – it’s not worth the risk of damaging your retinas. An expert observer with a carefully-aimed telescope might pick it up, but must use extreme caution that sunlight not enter the field of view. Come sunset, the distance widens again to a somewhat more comfortable 2.5 degrees.

Once, when following Venus as a crescent through inferior conjunction, I dared track it within 2.5 degrees of the sun. THAT was almost too close for comfort. I had to avert my vision from a brilliant wedge of internally reflected sunlight along one side of the view and wear sunglasses to temper the brilliance of the “safe zone” where Venus appeared.. Red and polarizing filters can help reduce glare and increase contrast for near-sun viewing of comets and planets.

Comet McNaught on Jan. 13, 2007 photographed with a 500mm lens. "Comet was easily visible by naked eye," said photographer Mark Vornhusen of Gais, Switzerland. Click to enlarge — Comet McNaught on Jan. 13, 2007 photographed with a 500mm lens. “Comet was easily visible by naked eye,” said photographer Mark Vornhusen of Gais, Switzerland. Will ISON give us a similar show? Click to enlarge. Credit: Mark Vornhusen / Wikipedia

In mid-January 2007, Comet C/2006 P1 McNaught had a similar close brush with the sun and peaked around magnitude -5. For several days around perihelion on Jan. 12 it was plainly visible with the naked eye in broad daylight. I spotted it 5.6 degrees from the sun at magnitude -3.5 (twice as faint as Venus) at 10 a.m. on Jan. 13 and 5 degrees from the sun the following day when I estimated its magnitude at -4.5. While close, 5 degrees is a much more comfortable distance for comet and inner planet viewing.

Example using a rooftop to block the sun so you can search near it for any sign of the comet. If using binoculars, BE SURE you focus them at infinity before daytime comet hunting otherwise there's no way to know if the comet will be in focus. I use clouds (the best) or a distant treeline. Credit: Bob King — Example using a rooftop to block the sun. When using binoculars for daytime comet hunting, BE SURE you focus them first at infinity otherwise there’s no way to know if the comet will be in focus. I use clouds (the best) or a distant treeline. Credit: Bob King

Whether naked eye, binocular or telescope, the favorite method for finding Comet McNaught in 2007 remains the best for Comet ISON in 2013. Block out the sun by placing something with a crisp edge in its way. Power poles, street lights (finally a good use for them), buildings, roof gables, church steeples and even clouds make ideal sun filters. They effectively remove the sun and allow you to look as close as is safe. Safety is critical here – never look directly at the sun. The damage to your retina will be swift and painless. No comet is worth losing your precious sense of sight.

As Earth rotates, the sun slowly moves across the sky. When using binoculars, if you start to see a bright reflection from approaching sunlight in the field of view, shift your position and re-cover the sun. I’ve been asked if you can simply hold an appropriate solar filter over your eye to dim the sun. Yes you can, but the filter will also completely block your view of the much, much fainter comet. Use the filter instead to dim the sun so you can hunt nearby for the comet.

Use these little pictures to help you know in what direction from the sun to look for Comet ISON every 2 hours from 8 a.m. to 2 p.m. CST Thursday Nov. 28. Stellarium — Use these little pictures to help you know what direction from the sun to look for Comet ISON between 8 a.m. and 2 p.m. CST Thursday Nov. 28. Add one hour for Eastern time; subtract 1 hour for Mountain and 2 hours for Pacific. Be sure to face the direction shown when using the diagrams and completely block the sun from view. Stellarium

Our final view shows the comet shortly before sunset in the southwestern sky when it lie about 2.5 degrees directly above the sun. — Our final view shows the comet shortly before sunset in the southwestern sky when it lie about 2-2.5 degrees directly above the sun. Time is 4 p.m. CST

Since ISON will be 2.5 degrees from the sun in the early morning and again just before sunset, those might be the best times to find it. Compared to the hour or two around perihelion, the glare will be less though ISON will likely be a little fainter. You can use the diagram above, suitable for mid-northern latitudes, to know in what direction from the sun to look for the comet. If ISON becomes at least as bright as Venus and your sky is deep blue and haze-free, you might just see it on Thursday before sitting down to that Thanksgiving turkey dinner. But of course much depends upon the comet.

Comet ISON will be under constant view Nov. 27-30 in the SOHO coronagraph, an instrument that blocks the sun so scientists can study the near-solar environment. Click to see images. Credit: NASA/ESA

Don’t fret if it’s cloudy. Head over to the Solar and Heliospheric (SOHO) website. There you’ll have a ringside seat Nov. 27-30 as Comet ISON makes its death-defying turn around the sun. Thereafter it will appear risk-free in the morning sky with what we hope will be a beautiful tail.

November 18, 2013December 23, 2015 by Bob King

Comet ISON Grows Wings; Comet Lovejoy, a Fountain

Comet ISON on Nov. 17 with a tail nearly 8 degrees long and small, highly condensed coma! It looks more like a jet contrail. Credit: Michael Jaeger

Wonderful photos of Comets ISON and Lovejoy with their swollen comas and developing tails have appeared on these pages, but recently, amateur and professional astronomers have probed deeper to discover fascinating dust structures emanating from their very cores. Most comets possess a fuzzy, starlike pseudo-nucleus glowing near the center of the coma. Hidden within this minute luminous cocoon of haze and gas lies the true comet nucleus, a dark, icy body that typically spans from a few to 10 kilometers wide. Comet ISON’s nucleus could be as large as several kilometers and hefty enough (we hope!) to survive its close call with the sun on Nov. 28.

Sketch using Photoshop of the inner region of Comet Lovejoy's coma showing the false nucleus and the curious dust fountain observed on Nov. 13 in a 15-inch (37-cm) telescope. Credit: Bob King. The dust fountain or plume captured on Nov. 12 next to the false nucleus deep within the coma of Comet Lovejoy. Credit: Luc Arnold — Sketch using Photoshop of the inner region of Comet Lovejoy’s coma showing the false nucleus and the curious dust fountain observed on Nov. 13 in a 15-inch (37-cm) telescope. Credit: Bob King. At right the same plume photographed on Nov. 12 with north up and east to the left. Credit: Luc Arnold

Last Wednesday morning Nov. 13 when calm air allowed a sharp view inside Comet Lovejoy’s large, 15-arc-minute-wide coma I noticed something odd about the false nucleus at low magnification, so I upped the power to 287x for a closer look. Extending from the fuzzy core in the sunward direction was a small cone or fountain-shaped structure of denser, brighter dust shaped like a miniature comet. It stretched eastward from the center and wrapped slightly to the south. Usually it’s harder than heck to see any details within the fuzzy, low-contrast environment of a comet’s coma unless that comet is close to Earth and actively spewing dust and ice. Lovejoy scored on both.

Negative image taken Nov. 14 of Lovejoy's nucleus and dust fan. Credit: Dr. P. Clay Sherrod — Negative image taken Nov. 14 of Lovejoy’s nucleus and dust fan. North up, west to the right. Credit: Dr. P. Clay Sherrod

By good fortune, Dr. P. Clay Sherrod of the Arkansas Sky Observatories, USA, and Luc Arnold of Saint-Michel-l’Observatoire, France, shared images they’d made at high magnification of the identical feature right at the same time as my own observation. There’s no doubt that what we saw was a jet or combined jets of dust and vapor blasting from Lovejoy’s true nucleus. Jets are linear or fan-shaped features and carry ice, dust and even snowballs from inside the nucleus out into space. They typically form where freshly-exposed ice from breaks or fissures in the comet’s crust vaporizes in the sun’s heat.

What I wouldn’t give to see one up close. Wait – we can. Take a look at the photo of Comet 103P/Hartley made during NASA’s EPOXI flyby mission in November 2010. Notice that most of Hartley’s crust appears intact with the jets being the main contributors to the dust and gas that form the coma and tail.

Multiple jets were actively spewing ice and dust when NASA's EPOXI mission zoomed by Comet Hartley 2 in November 2010. Credit: NASA — Multiple jets were actively spewing ice and dust when NASA’s EPOXI mission zoomed by Comet Hartley 2 in November 2010. The fuzzy spots are balls of fluffy snowballs measuring between 1 inch and 1 foot across. Credit: NASA

Spotting a jet usually requires good seeing (low atmospheric turbulence) and high magnification. They’re low-contrast features but worth searching for in any bright comet. Jets often point toward the sun for good reason – the sunward side of the comet is where the heating is happening. Activity dies back as the comet rotates to face away from the sun during the night and early morning hours. By studying the material streaming away from a comet via jets, astronomers can determine the rotation period of the nucleus.

Nightly images of Comet Hale-Bopp made March 24-30, 1997 by Brad D. Wallis of the Cassini imaging team at JPL. The photos were assembled into this animation by Sky & Telescope — Nightly images of Comet Hale-Bopp’s rotating nucleus and spiraling jet made March 24-30, 1997 by Brad D. Wallis of JPL. The photos were assembled into this animation by Sky & Telescope

Sometimes material sprayed by jets expands into a curved parabolic hood within the coma. This may explain the wing-shaped structures poking out from Comet ISON’s coma seen in recent photos. Possibly the Nov. 13-14 outburst released a great deal of fresh dust that’s now being pushed back toward the tail by the ever-increasing pressure of sunlight as the comet approaches perihelion.

The inner coma of Comet Hale-Bopp developed a striking series of hoods in March 1997 when a dust jet spewed material night after night from the comet’s rotating nucleus. The animation captures garden sprinkler effect beautifully. Since the nucleus spun around every 11 hours 46 minutes, multiple spiraling waves passed through the coma in the sunward direction. To the delight of amateur astronomers at the time, they were plainly visible through the telescope.

Processed images showing a possible jet next to Comet ISON' nucleus as well as the new wing-like coma structures on Nov. 17, 2013. The jet's position angle or PA is 150 degrees or southeast of the nucleus. Credit: Denis Buczynski and Nick James — Processed images showing a possible jet extending southeast (PA 150 degrees) of Comet ISON’s nucleus as well as the new wing-like hoods on Nov. 17, 2013. Credit: Denis Buczynski and Nick James of the BAA

When examining a comet, I start at low magnification and note coma shape, compactness and color as well as tail form and length and details like the presence of streamers or knots. Then I crank up the power and carefully study the area around the nucleus. Surprises may await your careful gaze. If Comet ISON does break up, the first sign of it happening might be an elongation or stretching of the false nucleus. If it’s no longer a small, star-like disk or if you notice a fainter, second nucleus tailward of the main, the comet’s days may be numbered.

Symmetrical "wings" photographed branching from Comet ISON's coma on Nov. 15. At right, the photo has been specially processed to show the structure more clearly. Credit: Erik Bryssinck — Another view of the symmetrical “wings” photographed branching from Comet ISON’s coma on Nov. 15. At right, the photo has been specially processed to show the structure more clearly. Credit: Erik Bryssinck

November 15, 2013December 23, 2015 by Bob King

See Comet ISON Fly through Earth’s Sky with this Awesome Interactive Simulator

Frame grab from the "Earth view" of Comet ISON from Inove's simulator. The horizontal line is the horizon and the comet's position is shown around 5:30 a.m. at the start of dawn today Nov. 15. The sun is in Libra and still well below the horizon at that time. Credit: INOUVE

Here’s a handy tool. The folks at INOVE Space Models have just updated their awesome Comet ISON flyby simulation with a second point of view – how it looks from Earth. The first version let us watch from afar as ISON dives across across the solar system until it makes a hard left at the sun and returns to deep space. The new view lets you watch it track across the sky across from any location on Earth. Go to the link and toggle the Switch to Earth option in the upper left of the display and you’re off. The website attempts to automatically pinpoint where you are, but for me it was a tad off, selecting a town about 75 miles away. But a few miles this way or that make little difference given how far the comet is from Earth. If you need to make an adjustment, click the Location icon (upper right) and select your latitude and longitude.

Comet ISON on perihelion day (Nov. 28) seen from the Upper Midwest, U.S. The sun and comet will be in Scorpius. Credit: INOVE — *Simulation of Comet ISON at noon CST on perihelion day (Nov. 28) seen from the Upper Midwest, U.S.A. The sun and comet will be in Scorpius. Credit: INOVE*

You have two options for viewing. If you click the single arrow play button at the bottom of the screen, the display shows a horizon line with the stars, sun and comet rising and setting over a single day. In a day’s time the comet moves only a small distance in the sky, so it will appear in nearly the same spot the next day. Except around perihelion on Nov. 28. Then it moves so quickly – over 800,000 mph (1.3 million km) – fast enough to watch move hour by hour.

Besides just being plain cool to watch, the simulator is truly useful. The background star field shows constellation outlines and stars down to about 5th magnitude. Assuming the comet is reasonably bright, say 5th magnitude or brighter, you can use the simulations as locator maps now through the end of January. By clicking on the Time Box at upper right, you can set it to any time you like, grab a frame and head outside for a look.

*Spectacular photo of Comet ISON taken this morning Nov. 15 from Charleston, Rhode Island, USA showing the recent outburst. Click to enlarge. Credit: Scott MacNeill*

Pressing the double arrow fast-forward button shows changes in position one day after another. To know what day you’re on just consult the timeline at the bottom of your screen. You can manually pull the time arrow to speed up, slow down or select a particular time of month. Other refinements are available in the Options box at upper left. Should you tire with Comet ISON from an earthly perspective, just click on Switch to Space at upper left and you’ll zoom back out for a solar system perspective. Enjoy the journey!

Another view of Comet ISON this morning photographed by Leonid Elenin

The un-simulated Comet ISON underwent a powerful outburst on Nov. 14 brightening by two magnitudes, as the two images here from Leonid Elenin and Scott MacNeil attest (and you can see more in our article from yesterday)

What had been a faint object in binoculars has become much more impressive. I caught it in my 10x50s in some small cracks between the clouds this morning (Nov. 15) and estimated its magnitude at 5.0. Had it been clear, I would have seen it with the naked eye. Through a 15-inch (37 cm) telescope at 64x the coma, now twice its pre-outburst diameter, glowed more blue than green with a dense core that looked like a bright, fuzzy star. Frankly, ISON was beautiful. Let’s hope this little outburst leads to better things to come and not early signs of the comet’s dissolution. Take a look yourself at the next opportunity and there might be a surprise waiting for you.