Triple shadow transit makes for triple the fun

Will Gator shot this excellent series of Jupiter portraits during different phases of the triple shadow transit last night and this morning with an 8-inch telescope. North is up and east to the left. In “D”, the top “dot” on the left side is the moon Callisto. The others are the shadows of (l-r) Europa, Callisto and Io. Credit: Will Gator

I had to dog last night’s triple shadow transit to see it but I’m glad I did. We had clouds nearly the entire time. But even with a crummy sky, Jupiter was bright enough to push through the ceiling at key times during the event.

Through the scope the planet drew a sharp profile with nice cloud belt detail. It was really fun to watch Io’s shadow catch up with and merge with Callisto’s shadow and then separate (panel C above). For a while the two looked like an headless ant or “negative double star”. Even more amazing was seeing the moon Io overlap Callisto’s shadow at 12:20 a.m.

For just a few minutes, Callisto’s black shadow turned a pale orange-gray, obviously lighter in tone than the neighboring shadow of Io. It simply looked wrong! Three minutes later Callisto returned as the biggest and most dominant shadow. Never seen anything like it.

When Europa squeezed onto the Jupiter’s disk at around 12:30 a.m. the show moved into high gear. It took a bit of concentration to see Europa as it casts the smallest shadow of the four Galilean moons. Just to its south, along the southern edge of the South Equatorial Belt, I could easily make out the moon Callisto. I managed about seven minutes of triple shadow viewing before the clouds became impenetrable.

After packing all the equipment away, I happily sat down and shared a glass of wine with my wife. Hope we’re all still around for 2032 when the next trifecta takes place.

Guide to Friday’s rare triple moon shadow-blast on Jupiter

Shadow transit of Jupiter’s moon Io captured on January 8th this year. Late this Friday night, Io, Europa and Callisto will cast their shadows simultaneously on the planet in a rare triple shadow transit event. Credit: John Chumack

We’re down for a very rare event this weekend that won’t happen again until December 30, 2032 – at least across the Americas. Between 12:28 – 12:52 a.m. (CST) Saturday morning, Jupiter’s moons Io, Europa and Callisto will simultaneously cast shadows on the planet’s cloud tops. Naturally, you’ll need a telescope to see this but only a modest one. You can follow the entire show in a 4 1/2 inch or larger instrument magnifying around 75x.

As Galileo was the first to note, Jupiter’s four brightest moons – Europa, Io, Callisto and Ganymede – revolve about the planet like a solar system in miniature. Each has its own period of revolution ranging from 1.7 days for innermost Io to 16.7 days for more distant Callisto. The moons periodically pass behind the planet (and temporarily get hidden from view), off to one side where they pass through Jupiter’s shadow in eclipse and in front of the planet.

Simulation of Jupiter around 12:40 a.m. (CST) Saturday, January 24th. Two moons and all three shadows will appear projected against the planet’s pale white equatorial zone.
Created with WinJUPOS

When in front of Jupiter, the moons cast their own shadows on its cloud tops. Through a telescope they look like jet black pinpoints for the smaller satellites (Io, Europa) and small dots for Callisto and Ganymede. Amateur astronomers look forward to watching these black dots move across the Jupiter’s cloud belt in part because we’re watching an eclipse happening on another planet. Imagine if you were there within the shadow looking back toward the Sun. From that perspective the moon would cover the Sun in partial or total eclipse. Cool thought.

So here’s the deal. One shadow transit every so often isn’t unusual, two at the same time is more so and a triple happens on average only once or twice every decade. In a word, don’t miss this opportunity.

If you want to catch all three shadows, you’ve got 24 minutes between 12:28 and 12:52 a.m. (CST) Saturday morning January 24th. Before and after that slot, you’ll see the shadows of one or two of the moons but not all three. Below is a list of the CST times, with Universal or UT times in parentheses) when each shadow enters and exits the planet’s face. To convert to your time zone, add an hour for Eastern time, subtract an hour for Mountain and 2 hours for Pacific.

Friday night Jan. 23 – Saturday morning Jan. 24:

* Callisto’s shadow enters disk – 9:11 p.m. (3:11 UT)
* Io’s shadow enters disk – 10:35 p.m. (4:35 UT)
* Europa’s shadow enters the disk – 12:28 a.m. (6:28 UT)
** TRIPLE TRANSIT from 12:28 – 12:52 a.m. (6:28 – 6:52 UT)
* Io’s shadow leaves disk – 12:52 a.m. (6:52 UT)
* Callisto’s shadow leaves disk – 2:00 a.m. (8:00 UT)
* Europa’s shadow leaves disk – 3:22 a.m. (9:22 UT)

Jupiter at 11:52 p.m. (CST) Friday night when Io and Callisto’s shadows will appear to merge. Meanwhile, Io undergoes a partial eclipse in the shadow “beam” cast by Callisto. Source: WinJUPOS

This triple event is unique enough, but there’s even more happening in what I like to call the “pre-game show”. As each moon enters the planet’s face like actors in a play, their shadows will cross over and bump into one another. I’ve included diagrams showing what to expect. For more details on the triple play and special events leading up to it I hope you won’t mind clicking over to this article I wrote for Sky and Telescope online.

The pre-game show wraps up with the moon Io transiting over Callisto’s shadow around 12:20 a.m. CST. The change in the shadow’s appearance should be obvious to the eye. Source: WinJUPOS

Since it was overcast here for the last triple shadow transit in October 11-12, 2013 you can imagine how much I’d like to see clear skies this time around. 2032′s a long, long ways out.

Once-in-6-year-alignment makes Jupiter’s moons dance in shadows

Jupiter and his Great Red Spot photographed on January 3rd through a 14-inch telescope. Credit: Paul Maxson

Now that Jupiter’s up in the east by 9 o’clock local time, we have lots of opportunities to observe it before bedtime. That’s good because the Jupiter system is currently edge-on to the Earth and Sun, allowing us to see the planet’s brightest moons eclipse and occult one another now through August.

Io, Europa, Ganymede and Callisto all orbit very close to the plane of Jupiter’s equator. From our perspective on Earth, the moons usually pass a little above or below one another and escape each other’s shadows. But every six years or so, Earth and Sun cross the plane of the satellites’ orbits putting us “level” with Jupiter’s equator.

Instead of missing one another, the moons appear to merge into one during occultations and cast their shadows on one another during eclipses. This cyclic but relatively rare planetary alignment last happened in 2009 and won’t again until 2020.

The six varieties of eclipses and occultations possible among Jupiter’s four brightest moons now through August. Credit: Dave Dickinson

While you may not be able to resolve the four brightest moons in your telescope, you’ll have no difficulty watching them approach one another and meld into either an extremely close “double moon” or a single object during an occultation. Minutes later, the pair breaks apart as each moon follows its own track around the mothership.

Io eclipses Ganymede back on August 16, 2009. Credit: Christopher Go

During an eclipse, one moons will cast a shadow on another, causing it to fade the same way our moon dims when entering Earth’s shadow during a lunar eclipse. Assuming a fairly deep eclipse, you’ll be able to watch a Jovian moon fade and then re-brighten in a matter of minutes.

Again, you won’t see the shadow itself because the moons are so tiny, but the drop in brightness is clearly visible especially during deep eclipses.

With Jupiter coming to opposition on February 6th you’ll have lots of opportunities to catch at least one of each type of phenomenon. Not to mention, that all the moons cross over the Jupiter’s bright equatorial zone as they orbit the planet, making shadows they cast on the cloudtops easier than ever to see. Those are called shadow transits, and we’ll feature those soon, too.

Io eclipses Ganymede on Christmas night 2014. Credit: Paul Maxson

Below is a list of the best upcoming mutual events of the four brightest satellites for locations across North America. To view them, you’ll need at 3-inch or larger telescope.

A drop of 0.5 magnitude or larger during an eclipse or occultation should be apparent to the eye by carefully comparing before and after views. For occultations, you can also have the pleasure of seeing the moons in close embrace

Two for the price of one. Io occults and then eclipses Europa in this animation of still photographs taken on September 28, 2009. Credit: Brian Combs

For a customized table of events when Jupiter’s easily visible in a dark sky from your location, click over to this list of observatories, do a Control-F (Command-F on Mac) and type in the name of a larger city within a few hundred miles of your location. Next, copy the 3-digit code number and then paste it into the window on the IMCCE table creation page. Click enter and you’ll get a handy list of every event visible from your location through August.

To help you pick which eclipse events are worth your time, make sure the “Δm” (change in magnitude) is 0.5 or greater. Times listed in the table are Universal Time. Subtract 5 hours for EST, 6 for CDT, 7 for MST and 8 for PST. Also, each moon is listed by number rather than name. Io=1, Europa=2, Ganymede=3 and Callisto=4, so “2e4″ means Europa eclipses Callisto.

More event information and some great animations are available at SAF Planetary Observation Commission’s page.

Events – Times are CST:

Jan. 15 – Io eclipses Callisto starting 6:13 a.m., ending 6:39 a.m. Magnitude drop: 0.5
Jan. 18 – Ganymede occults Europa starting 8:31 p.m., ending 8:37 p.m. Mag. drop: 0.5
Jan. 23 – Callisto eclipses Ganymede starting 3:06 a.m., ending 3:20 a.m. Mag. drop 1.4!
Jan. 25 – Ganymede occults Europa starting 11:13 p.m., ending 11:19 p.m. Mag. drop 0.5
Jan. 28 – Europa eclipses Io starting starting 12:18 a.m., ending 12:27 a.m. Mag. drop 0.5
Jan. 29 – Io occults Europa starting  8:31 a.m., ending 8:35 a.m. Mag. drop 0.6

Nice sequence showing Io occulting Ganymede on December 21, 2014. The moons meet and part over 22 minutes. Credit: Paulo Casquinha

Bear in mind, these are the most easily observed events. There are many more! I’ll post a new list at the beginning of every month through the summer. Let us know if you get to see one of these. Good luck!

Tie down the furniture honey, tomorrow’s Zero G Day!

Will you float into the air tomorrow morning January 4th? Read on to find out your chances of success. Credit: Rob Wink (flickr.com/photos/rlw-photos/)

If you wake up levitating over your bed tomorrow morning at 9:47 a.m. (PST) you have a very active imagination. According to a recent article published the Daily Buzz Live, that’s when Pluto and Jupiter will align. Their combined gravity will temporarily counteract Earth’s gravitational pull and make us all virtually weightless for several minutes.

The story goes on. If you jump in the air “it should take you about 3 seconds to land back on your feet instead of the usual 0.2 seconds.”

Accompanying the story is an authentic-looking tweet that appears to come from NASA.

Who wouldn’t like to float in the air? In one of my favorite recurring dreams I jump in the air and float like an astronaut for many minutes, turning and navigating with just a twist of my body.

Well, unless you’re on board the International Space Station or an astronaut training in NASA’s “vomit comet”, a special designed KC-135 airplane that flies deep parabolic loops to briefly simulate zero-g, don’t worry about nailing down the furniture tomorrow morning.

Fake tweet from purportedly from NASA that accompanied the story in Daily Buzz Live. Gotta love that end-of-the-world-as-we-know-it hashtag #beready!

Of course this is all a hoax. While the tweet is fake and serves to legitimize the claim, the story does have a factual origin. The prediction was first made by none other than Sir Patrick Moore, a well-known and beloved British astronomy popularizer.

On April 1, 1976 during a BBC radio show, Moore announced a once-in-a-lifetime opportunity that would occur when Pluto passed temporarily behind Jupiter. Listeners were advised that if they jumped at exactly 9:47 a.m. that day they’d experience a temporary sensation of weightlessness. The show was an April Fool’s Day spoof, the prediction a joke. Yet people actually called in claiming to have been lifted off the ground.

We are suggestible lot. We see a dark shape down the road in moonlight and imagine a hulking animal when it’s only the neighbor’s garbage can. It’s a wonderful ability because it prepares us for the unexpected, but we need to leaven this skill with logic.

Levitation on the home planet is unlikely for the moment except in the hands of creative photographers. Credit: Rachel Marie Smith

Let’s put on our critical thinking caps and start poking some holes. Assuming you weren’t familiar with the April Fool’s story, how would you proceed in debunking the claim?

You might first check whether Pluto and Jupiter are lined up on January 4th. That’s easy. Open up one of many star-charting programs like Stellarium and you’ll quickly discover that Jupiter shines in the evening sky in Leo. Pluto is in the opposite part of the sky in Sagittarius and invisible in the glare of the Sun.

Your suspicions should also be aroused by googling a bio of Patrick Moore. There you’ll discover he died two years ago. The Buzz story is written in the present tense as if Moore were still alive. Another red flag.

Jupiter and Venus in conjunction at dawn over Lake Superior on June 30, 2012. Planetary alignments can’t be physically sensed by us on Earth. Even their combined gravity is too weak to detect at the human scale. Credit: Bob King

Finally, contrary to urban myth and a zillion Youtube doomsday-scenario videos, planetary alignments do not affect life on Earth in any significant way. While massive Jupiter has a powerful gravitational pull, it decreases rapidly with distance. The amount of tugging you feel from the planet here on Earth is the same gravitational force exerted by a compact car three feet (1 meter) away. Pluto is really tiny with a far weaker pull. Putting them together does not magically magnify their gravitational reach.

You can line up all the planets, the Sun and moon in row and still go about your day with absolutely no sensation from their combined gravities. The moon and Sun are by far the strongest gravitational entities in the solar system in terms of their effects on Earth. Though only 2,160 miles in diameter, the moon is close enough to produce the tides, while the Sun is distant but far more massive than all the planets combined.

A few times a year the Sun and moon perfectly align in a total solar eclipse. Ever heard of someone hovering above the ground during totality? Me neither. Except in a spiritual sense of course!

The next time you hear of crazy claims being made about alignments and such, be skeptical. If the Internet has taught us anything, it’s to exercise critical thinking whenever we sit down in front of the flickering screen.

Stargazing on Christmas night

Merry Christmas and a happy holiday! I hope you’re enjoying time with family and friends and a clear night is in the forecast. Should you poke your head out tonight, here’s what’s up.

Look for the crescent moon and Mars in the southwestern sky at the end of twilight tonight December 25th. Comet Finlay and Mars will still be tight the next few nights.  The alignment is line-of-sight only — the two are actually about 45 million miles apart. Stellarium

At nightfall, a pretty crescent moon ornaments the dim constellation of Capricornus not far from Mars. Barely half a degree to the planet’s east a 6-inch or larger telescope will net you Comet 15P/Finlay, now fading from its recent outburst. It’s currently magnitude 9.6 with a little tail pointing to the east.

Comet 15P/Finlay passed only 1/6th of a degree from Mars on December 23-24. This photo was taken on the 24th and shows the glaring planet and comet almost touching. Click for a map to help you find Finlay in your telescope. Credit: Damian Peach

In a remarkable coincidence, comets have passed very close to the planet Mars twice this year. Comet Siding Spring drew physically close on and around October 19th, while Comet Finlay only appears next to the planet thanks to a lucky line-of-sight alignment.

A grand entry of stars dances across the southeastern sky around 10 o’clock local time. Comet C/2014 Q2 Lovejoy will be 10° high at that hour in the constellation Columba the Dove as seen from the northern U.S. and even higher from the central and southern states. Stellarium

Later tonight, around 10 o’clock, look to the south. Orion has now climbed boldly into view along with sparkling Sirius and the “Winter Triangle” figure. Tucked below Lepus the Hare you’ll find our Christmas comet, Lovejoy, now glowing at magnitude 5.5 and faintly visible to the naked eye from a dark sky location. Binoculars show it as a big ball of fuzz. For more information and a map showing its travels in the coming nights, click HERE.

Comet Lovejoy on December 23 looks like a Roman candle with a blue coma and long, faint tail. Credit: Michael Jaeger

Photos of Lovejoy show a huge coma or comet atmosphere more than half the size of the full moon tinted green from fluorescing carbon and cyanogen molecules; its super-skinny tail glows blue from light given off by carbon monoxide excited by ultraviolet light from the Sun.

Jupiter is easy to see now in the eastern sky in Leo around 10 o’clock local time. Stellarium

If you now direct your gaze to the east around 10 p.m., Jupiter jumps right out. After Sirius and the moon, it’s the brightest nighttime object the sky this winter. Use the planet to help you find the Sickle or head of Leo the Lion and its brightest star, Regulus.

Jupiter in binoculars tonight around 10 p.m. (CST). All four of its bright moons will be strung out in a nearly straight line very close to the planet (big glow at center). Stellarium

Sharply-focused and steadily held 10x binoculars will show all four of its bright moons, assuming one or more aren’t passing either behind or front of the planet or in eclipse. Lucky for us, Io, Europa and Ganymede will line up in a neat row east of Jupiter with Callisto well off to its west tonight. How many will you see?

Wow! What a blast. This fireball lit up Japanese skies early this morning. The Belt of Orion is at upper right. Credit: SonotaCo

Finally, reports are coming in about a powerfully bright fireball that streaked across Japan’s skies around 2 a.m. local time this Christmas morning. I’ve not been able to track down a brightness estimate, but the pictures show an object at least as brilliant as the full moon.

Moon and Jupiter with a side of JUICE, please

The waning gibbous moon lingers near Jupiter tonight and tomorrow night (Dec. 11) in the constellation Leo. This map shows the sky facing east around 11 p.m. local time. Source: Stellarium

Find the moon tonight and you’ll be led straight to Jupiter. Tomorrow night, too. Earth’s only satellite will spend the next two evenings wooing the largest planet which shines brightly to the west of Leo’s Sickle.

As Jupiter rises earlier and earlier, pushing higher into the evening sky, the European Space Agency’s JUpiter ICy moons Explorer Mission or JUICE recently got the green light to proceed to the next stage of development – working out the details of payload equipment and mission support among the many partners involved in the project.

JUICE will launch in 2022 and arrive at Jupiter in 2030 to begin a three-year-plus study of the giant planet and three of its largest moons – Ganymede, Callisto and Europa. The spacecraft will bristle with cameras, spectrometers, a radar, an altimeter, radio science experiments and sensors used to monitor the flow of charged particles (electrons, protons and others) in the Jovian system.

Artist impression of JUICE at Jupiter in the year 2030. JUICE will spend part of its mission in orbit around Ganymede, the moon at upper left. Credit: ESA/AOES

Scientists will explore Jupiter’s atmosphere, tenuous dust ring and its magnetosphere, a bubble of magnetism that enshrouds the planet similar to the one that funnels the solar wind into Earth’s upper atmosphere to spark auroras. No surpries – Jupiter has auroras, too.

JUICE will also investigate each of the three moons up close and their interactions with Jupiter, especially Ganymede. Detailed investigations Ganymede, the planet’s largest moon, will be performed when the probe enters into orbit around it – the first time any moon other than our own has been orbited by a spacecraft.

Europa, Ganymede and Callisto are all believed to hold oceans of liquid water beneath their frigid crusts. The mission will study the moons as potential habitats for life as it seeks to determine what conditions are required for planet and moon formation and the emergence of life.

This artist’s concept of Jupiter’s moon Ganymede, the largest moon in the solar system, illustrates the “club sandwich” model of its interior oceans. Credit: NASA/JPL-Caltech

JUICE will first visit Callisto, the most cratered object in the solar system, then fly by Europa twice, making measurements of the thickness of its icy crust. In 2032 the spacecraft will enter into orbit around Ganymede and study both its surface and internal structure including that possible hidden ocean.

“JUICE will give us better insight into how gas giants and their orbiting worlds form, and their potential for hosting life,” said Prof. Alvaro Gimenez Canete, ESA’s Director of Science and Robotic Exploration.

Did Jupiter deport 8 billion asteroids to the Oort Cloud?

1996 PW has a highly elongated orbit  just like a comet from the Oort Cloud – except it’s an asteroid. Astronomers now think they know how it got there. 1996 PW is about 5-10 miles (8-16 km) across. Credit: NASA/JPL-Horizons

Our view of the solar system will forever be incomplete. While frustrating at first blush, it means that fresh discoveries are always just around the corner. Case in point. On August 9, 1996 astronomers atop Mt. Haleakala in Maui, Hawaii discovered a most peculiar asteroid. 1996 PW has a highly elongated that looks like a Frisbee seen from the side and takes 5,900 years to make one trip around the Sun.

When farthest, 1996 PW is 48.8 billion miles away or 104 times more distant than Pluto. That places it among the billions of icy comets that comprise the Oort Cloud, a roughly spherical cocoon centered on the Sun and extending up to a light year from it in all directions.

Like moths around the solar flame, some 500 billion comets and perhaps 8 billion asteroids occupy a vast region of space called the Oort Cloud. The Kuiper Belt is a second asteroid belt that lies beyond the orbit of Neptune.

Odd thing was, 1996 PW was an asteroid – it never exhibited a fuzzy coma or tail typical of a comet and appeared spectroscopically to be made of rock. No dust or gas of any kind was detected even when the object was closest to the Sun. So what was it doing so far from home?

Some astronomers thought it may have been an active comet long ago but depleted its ices to where it’s now unrecognizable from an asteroid. Maybe.

A new study by Andrew Shannon (University of Cambridge), based on simulations of the rolling-stone-ways of the giant planets early in the solar system’s history, points to 1996 PW once being much closer to the Sun.

The planets haven’t always been in their present day orbits. In particular, Jupiter, the largest and most gravitationally potent planet, roamed inward to the orbit of Mars before backing out to its present orbit. Gravitational interactions with the dusty disk of material around the Sun called the solar nebula pulled the planet in. Later, interaction with Saturn yanked it back out. Scientists dub the back-and-forth shimmy the “Grand Tack”.

Interaction between the dusty-gassy solar nebula surrounding the Sun the young solar system and Saturn caused Jupiter to migrate first inward and then outward, scattering the hapless asteroids as it came and went. Credit: NASA

“We refer to Jupiter’s path as the Grand Tack, because the big theme in this work is Jupiter migrating toward the sun and then stopping, turning around, and migrating back outward,” writes Kevin Walsh of the Southwest Research Institute in Boulder, Colorado in a 2011 paper in Nature. “This change in direction is like the course that a sailboat takes when it tacks around a buoy.”

Jupiter’s gravitational might profoundly affected the asteroid belt at the time. Based on Shannon’s computer simulations, the giant planet’s do-si-do created chaos, with some asteroids kicked toward the Sun, others moved to a newly-created main belt and still others booted right out of the solar system.

Many were also flung to the icy realm of the Oort just short of leaving the Sun’s domain altogether. Shannon estimates that 4% or 8 billion rocky asteroids that once orbited within 2.5 times Earth’s distance from the Sun now mingle among the cloud’s half-trillion comets. Heck, that’s more asteroids than populate the main asteroid belt!

Very few “Oort asteroids” have been discovered and you can guess why. They’re small, generally dark and incredibly far away. A comet gives itself away with a bright coma and tail. Not these guys.They’re lurkers. To find them we’ll need dedicated, large telescope surveys like the upcoming Large Synoptic Survey Telescope with its 8-meter mirror slated for “first light” in 2019. But even that great eye will be challenged – Shannon predicts only a dozen discoveries a decade with the wide-field survey telescope.

One interesting sidelight about Oort Cloud asteroids. Like comets, they do drop in on the inner solar system from time to time. 1996 PW comes within just 232 million miles (373 million km) of the Sun. If one ever did have Earth in its sights, it would be hard to spot in advance and more difficult to divert because its much faster speed. One the bright side, Shannon and team estimate an impact would occur only once every billion years. I guess I can handle those odds and drag myself to work another day.

The Moon, still young after all these years / See a Callisto eclipse!

The Moon and Mars gather in the west at dusk this evening. Stellarium

Tonight the returning young crescent Moon puts down stakes near the planet Mars in Sagittarius. Look for the pair low in the southwestern sky at dusk.

We’re used to hearing how ancient the Moon is. Its origin goes back to 4.48 billion years ago when a Mars-sized planet sideswiped the Earth, blasting debris into space that quickly coalesced into our satellite. While it’s true that most of the Moon’s crust and craters date from then, recent close-up photos from NASA’s Lunar Reconnaissance Orbiter (LRO) suggest the Moon remained volcanically active until not that very long ago. At least on geological time scales.

Ina Caldera, a classic IMP, sits atop a low, broad volcanic dome or shield volcano, where lava once oozed from the moon’s crust. The darker patches in the photo are blobs of older lunar crust. They  form a series of low mounds higher than the younger, jumbled terrain around them. Credit: NASA

100 million years ago, when dinosaurs cracked jokes about the early mammals, lava oozed from cracks in the Moon’s crust to create what astronomers nowadays call IMPs or Irregular Mare Patches. They’re characterized by a mixture of smooth, shallow mounds next to patches of rough, blocky terrain. Only one, called Ina, is large enough to see in amateur telescopes. The others, liberally sprinkled across the lunar nearside, are generally less than 1/3 mile (500 m) across. Using the LRO, a team of researchers led by Sarah Braden of Arizona State University has found 70 landscapes similar to Ina.

When it comes to the big picture, 100 million years is a small slice of Earth’s history. Credit: NASA

Maria (plural of “mare”) are those big dark spots the make up the face of the man in the moon. They’re actually huge expanses of lava that welled up from cracks in the Moon’s crust several billion years ago after asteroid impacts. IMPs are much more recent. Some may be as “young” as 50 million years old. This was well after the dinosaurs succumbed to major climate changes induced by the impact of a 6-mile-wide asteroid hit here on Earth. Now the mammals are cracking jokes about the dinos.

A selection of some of the 70 IMPs discovered during the survey. Credit: NASA

“Discovering new features on the lunar surface was thrilling!” says Braden. “We looked at hundreds of high-resolution images, and when I found a new IMP it was always the highlight of my day.”

Astronomers determine ages of lunar features by doing crater counts. The more lightly cratered an area is, the younger.

Here’s the scene tomorrow morning November 26th with all four of Jupiter’s bright moons. Callisto, which sits right next to Europa, will dramatically fade over several minutes time starting about 4:50 a.m. CST. Meanwhile, 15 minutes later at 5:05 a.m., Ganymede will exit its eclipse and return to view. Add one hour for EST, subtract an hour for MST and two hours for PDT. South is up. Stellarium

Some of you may be early morning observers. Well, I’ve got a special event to share with you. Tomorrow morning November 26th, Jupiter’s bright moon Callisto will be eclipsed by Jupiter’s shadow starting at 4:50 a.m. (CST) and disappear for nearly five hours.

Just 15 minutes after Callisto disappears, Ganymede emerges from eclipse at 5:05 a.m. (CST). One disappears, the other reappears. Pretty cool! Jupiter will be the brightest thing in the sky high in the south in Leo at the time. You can always find out what Jupiter’s moons anytime of day or night by visiting Sky and Telescope’s Jupiter’s Moons site.

Lively Leonid meteor shower peaks tomorrow, Tuesday

The annual Leonids peak this week. About a dozen per hour will be visible from a dark site. The shower’s known for fireballs that often leave persistant “smoke trails” or trains. Tony Hallas captured two Leonids in a single frame with glowing trains during the 2001 shower. Credit: Tony Hallas

Watch out for flammable comet dust the next few nights. ‘Tis the season of the Leonids. This annual meteor shower, which originates from dust dribbled by comet 55P/Temple-Tuttle, peaks tomorrow and Tuesday mornings November 17-18.

About every 33 years the Leonids produce a spectacular display. This illustration from a newspaper at the time captures the intensity of the shower on November 13, 1833. The next Leonid storm is expected in 2034.

Every 33 years, when the comet swings into the inner solar system, Leonid numbers swell into the hundreds if not thousands per hour and create what’s better described as a meteor storm. The most recent storm unfolded in 2000-2001; now we’re down to the Leonids’ usual peak of 10-15 per hour.

Admittedly, that’s more like a light drizzle than a shower, but what the Leonids lack in numbers in off-years, they make up for in character. Because the Leonid stream travels around the Sun in a direction opposite to the planets, Earth hits Tempel-Tuttle’s debris head-on at very high speed. Leonids pepper the planet at speeds upwards of 158,000 miles per hour (70 km/sec), the fastest of any shower.

They often burn brightly as fireballs and leave glowing streaks of ionized air in their wakes called trains. Upper atmospheric winds can distort and stretch the trains over several minutes time, a sight well worth watching. In 2001, we saw a fair number of these long-lasting “smoke trails” after the appearance of fireballs.

 

This map shows the sky facing east around 3 a.m. Monday November 17th. The radiant is well-placed near Jupiter in Leo. The thick crescent Moon rises around 2 a.m. Monday and 3 a.m. Tuesday. Stellarium

Watching the Leonids is easy as long as you’re willing to wake up in the wee hours. Patience helps too. You may see nothing in the first 10-15 minutes and then all at once a swift blade of light slices the sky. The radiant or point in the sky from which the meteors originate rises around 11:30 p.m. local time in Leo near Jupiter. But the best time to view the shower is from about 3 a.m. till dawn when the radiant is high in the east-southeast.

Both Monday and Tuesday mornings are good for shower watching. Light from the crescent Moon will hardly be a bother. Dress warmly and get comfy under a blanket in a reclining lawn chair facing east or south. Relax back and watch the stars slowly parade above you. Every meteor you see will come both as a pleasant surprise and reminder that Earth is continually touched by comets.

Guess who’s up before midnight? By Jove, it’s Jupiter!

Brilliant Jupiter now rises in the northeastern sky before midnight. The waning gibbous Moon will join the planet Thursday November 13th. This map shows the sky facing east at midnight in mid-November. Stellarium

If the sky’s seemed devoid of evening planets of late, you’re right. Mars still hangs on in Sagittarius, but it’s so low and sets so early, few notice. Most telescopic observers have long since abandoned the planet. With an apparent diameter of three-one-thousandth’s that of the Moon, it’s just too tiny to eke out any details.

Venus is also “officially” an evening planet but still much too close the Sun to view. Enter Jupiter. This jolly bright planet joins the evening crew with a bright flourish, rising in Leo the Lion. In the days of Daylight Saving Time it rose around 1 a.m. but now catches our eyes a little before midnight low in the northeastern sky.

Jolly Jove on November 8, 2014. The two big stripes are the North (top) and South Equatorial Belts. The Great Red Spot is seen along with a cluster of smaller oval storms. Credit: Christopher Go

Earth’s revolution around the Sun causes the stars and planets in the eastern sky to rise 4 minutes earlier each evening, while those in the west set 4 minutes earlier. Over time, stars in the west get pushed out of the way as those in the east rise higher and take over the sky. It’s the astronomical equivalent of seeing each older generation swept away by the little babes whose job it is to replace us.

My point is that Jupiter, while low now, will rise an hour earlier by Thanksgiving  (16 nights x 4 mins. = 64 minutes) and nearly 3 hours earlier by Christmas. We’re soon to see a lot more of this planet. So goes the cycle of the sky.

Three of Jupiter’s four bright moons will be visible in small telescopes tonight. This view shows them around midnight (CST) tonight. North is up. Stellarium

Not only is Jupiter a pleasure to see with the naked eye – it’s so darn bright – but its dynamic weather and four bright moons offer telescope users something new to see every time we look through the eyepiece.

Because Jupiter’s 11 times larger than Earth, it presents a huge disk compared to most planets. Even with a 3-inch scope you can watch the moons shuttle back and forth and spy the largest clouds belts. The Great Red Spot, an enormous hurricane-like storm, has been shrinking over the last decade but can still be spotted in 6-inch and larger instruments.

The 2014-2015 apparition of Jupiter is special because Earth crosses through the planet’s orbital plane. Since the four brightest moons orbit almost exactly around Jupiter’s equator, we’ll get to see them eclipse and occult one another. Eclipses are especially interesting to watch – over a few minutes time you can actually watch a moon temporarily fade away. I’ll have more on these fascinating events soon.