Comet Jacques zips through Cassiopeia – catch it this week!

Wow! Comet Jacques cuts between the Heart (right) and Soul Nebulae in Cassiopeia on August 19th. These clouds of fluorescing hydrogen gas are also known as IC 1845 and IC 1848. Click to enlarge. Credit: Michael Jaeger

Not many clear nights in my town lately – we had exactly one this week. I’m grateful because we finally got a peek at Comet Jacques, which recently climbed out of the morning sky into the familiar ‘W’ of Cassiopeia. That’s good news because it means you can spot Jacques now at nightfall instead of dawn.

Comet C/2014 E2 Jacques cruises through the W of Cassiopeia the next few nights. The view shows the sky facing northeast at nightfall in late August around 9:30 p.m. Click for a detailed map showing the comet’s position nightly through early September. Stellarium

Through a pair of 8x40s two nights ago, the comet was a faint, fuzzy patch next to the lower left star of the ‘W’. Jacques is currently making its closest approach to Earth; on August 28 it will pass us at 52.4 million miles (84 million km). While that’s a fair distance, its relative proximity causes it to move relatively quickly across the sky. Currently the comet’s puffing along at a couple degrees a day. Those with telescopes can easily see it shift position against the background stars within an hour.

Small telescopes will reveal Jacques’ largish diffuse coma and bright core. The core is where the icy nucleus hides behind a shroud of dust and gas vaporized by the heat of the sun. No one knows its exact size – thanks to all that dust – but it’s probably a mile or two across, typical of many comets.

36 pictures of Comet Jacques taken on August 17th combined into a movie show its motion and changes in its gas tail caused by interaction with the solar wind, a stream of subatomic particles blowing from the sun. Click to enlarge. Credit: Gianluca Masi

Larger scopes 8-inches and up will show varying amounts of the comet’s long, faint ion or gas tail that points to the southwest and a hint of green color in the coma from fluorescing gases.

Even though Jacques has been traveling away from the sun since closest approach on July 2, its brightness will remain nearly constant at magnitude +7 through early September because it’s ‘in the neighborhood’.

Try to spot it the next clear night. From a dark sky, the comet’s easy in binoculars and any telescope will show it. Moonlight won’t get in the way until early next month.

Know your planet and eat it too

A Jupiter cake made by Rhiannon, who writes the Cakecrumbs blog, shows the giant planet’s layered atmosphere and interior in a fun and realistic way. Click for recipe. Credit: Rhiannon

I had no idea Jupiter had a mud cake core surrounded by almond butter cake and enveloped with a blue-tinted vanilla Madeira sponge. Topped off with vanilla buttercream and marshmallow icing, it’s the first planet that’s ever made my mouth water.

The Great Red Spot inspired Rhiannon to pick Jupiter for her cake. The iconic feature is instantly recognizable. She used ivory, brown and maroon edible ink to dry brush the Spot and other atmospheric features like belts and vortices on the outer layer of marshmallow fondant (icing). Credit: Rhiannon /cakecrumbs.me

Rhiannon, who writes the Cakecrumbs blog, had two passions as a child, animals and the solar system. A self-taught cook and cake decorator, she recently created what she calls her “Jupiter Structural Layer Cake” based on current knowledge of the planet’s atmosphere and interior.

Why Jupiter? It wouldn’t surprise you to know that the Great Red Spot – that huge storm more than twice the size of Earth that’s been whirling around up there the past few hundred years – has always been one of her favorite outer space personalities.


Jupiter concentric layer cake tutorial

Painting on the Red Spot and many other atmospheric details, all based on photos of the planet over many years, took 8 hours, just 2 hours shy of one complete rotation of the real Jupiter. That’s dedication.

You’ll have to watch the video to appreciate the details (three baking steps were required), but to create the sphere, she joined two cake hemispheres with buttercream.

The non-cake Jupiter spans nearly 87,000 miles across and is striped with jet-stream like belts of ammonia ice clouds. Earth is shown for comparison. Credit: NASA

Rhiannon cautions that her cake is “totally not to scale”, but she’s got the details down. Jupiter’s marshmallow cream atmosphere is mostly hydrogen and helium with clouds made of ammonia ice and even water ice further down. All those lovely yellows, reds and oranges so lovingly applied with tiny brushstrokes of food coloring are likely trace amounts of compounds of sulfur, carbon and phosphorus in real life.

Below the clouds, Jupiter just gets weird. Its atmosphere reaches down for thousands of miles. In December 1995, NASA’s Galileo spacecraft released an Entry Probe toward the planet. As the craft descended into the maelstrom of Jovian clouds, it transmitted data back to the orbiter for just 58 minutes. At a depth of 373 miles (600 km), transmissions stopped as the machine was presumably crushed by the extreme atmospheric pressure. Pressures at the base of Jupiter’s atmosphere are 4 million times what we experience on Earth.

Cutaway showing both the cloudtops and the interior of Jupiter. About 75% of the planet’s weight is taken up by fluid metallic hydrogen. Jupiter’s composition is very similar to the sun’s, and like the sun, it’s very hot in the center, but not hot enough to ignite hydrogen and burn as a star.

It only gets more intense as you approach the core. At a certain depth, airy hydrogen is compressed by the vast amount of material above it into liquid molecular hydrogen (the blue cake layer). Below that we arrive at a truly exotic form of matter, liquid metallic hydrogen (white cake).

Under the extreme pressures and heat near the core, ordinary hydrogen gets squeezed so tightly, its electrons depart and move about just like they do in metals. And just as metals conduct electricity, so too this bizarre hydrogen cousin. If you could somehow touch it – impossible because it can’t be created on Earth – it would resemble liquid mercury.

Don’t care for Jupiter? How about a slice of Earth? This is one of Rhiannon’s earlier cakes. The slice shows the crust, mantle (red), outer core (yellow) and inner core. Credit: Rhiannon / cakecrumbs.me

Jupiter’s intense magnetic field is thought to arise from the rapid spinning of this electric liquid. Deeper down, we meet a putative core of rock (mud cake), something like the Earth in composition, but 10-15 times more massive.

Have you had enough cake yet?

 

Brief aurora Weds. Aug. 20-21 – maybe more overnight?

A low arc and dim green rays were topped by a red border in this photo taken around 11 p.m. CDT Wednesday night Aug. 20. Details: ISO 3200, f/2.8, 20mm lens. Credit: Bob King

Scandinavians were the lucky ones yesterday when auroras broke out during their nighttime. Here in the U.S. it was still afternoon. Auroras are mighty scarce in sunshine.

Tonight to my surprise, we had a brief display around 11 p.m. CDT.  An arc rose above Boulder Lake north of Duluth, Minn., where a group of naturalists and I spent the night at the telescope under a starry sky. At the sight of a few needle-thin rays, one in our group jumped in a canoe and paddled out into the lake for a better view.

More rays taken a few minutes after the first photo. The display was fairly quiet and reached to about 10 degrees above the northern horizon. Credit: Bob King

Not 15 minutes after it began, the arc and rays faded away, leaving only a faint, diffuse glow until fog settled in around midnight. The Kp index rose slightly during the evening, and the ACE satellite plot has shown a southward pointing Bz or solar magnetic field in Earth’s vicinity for many hours. This is often a good indicator of auroral activity on the way.

The show was subtle but no one was disappointed. Auroras are always welcome around here.

Aurora alert tonight Aug. 19-20 for northern U.S.

“Unbelievable,” says Reid Wiseman on seeing a spectacular auroral display from a window on the International Space Station this evening. This photo was tweeted out at 6 p.m. CDT. Credit: NASA/Reid Wiseman

The astronauts are seeing it from the space station. You and I just might too. A G2 moderate auroral storm kicked up this afternoon and early evening, and according to NOAA space weather experts, is expected to continue into the night.

Another shot of the aurora from orbit. “Never in my wildest dreams did I imagine this,” said Wiseman.

A coronal mass ejection (CME) caused by a filament or plume of hydrogen gas ejected a few days ago caused the sudden surge. The Kp index, a reliable indicator of magnetic activity in Earth’s upper atmosphere hit 6 earlier this evening. Should it ‘stick’ there, skywatchers in Canada and across the northern U.S. stand a good chance of seeing auroras tonight. Look to the north at the onset of night. I’ll keep you posted.

* Update 11 p.m. CDT: The Kp has plummeted to 2! That’s not good. It’s always possible that activity will shoot up again overnight. If you’re out tonight, take a look before going to bed.

Miss the conjunction? Here’s your consolation prize

Clear skies prevailed over Königswinter, Germany for a great view of Venus and Jupiter just 0.2° apart at dawn this morning August 18. Credit: Daniel Fischer

Those killers of all things astronomical – clouds – were back again this morning, so no Venus-Jupiter conjunction here. Looks like I’ll pin my hopes on the one scheduled for next June 30 in Leo at dusk. I’m grateful for the flatness of the solar system, which guarantees that every few years we get repeat planet pairings.

Look east this coming Saturday morning for a sweet pairing of the bright planets and wiry crescent moon. This view shows the sky about 45 minutes before sunrise. Stellarium

I hope some of you got to see the conjunction from your home or on the way to work this morning. While Venus and Jupiter will now part ways, they’ll be one more blast of celestial awesomeness involving the duo and the crescent moon this weekend. Consider it a consolation prize. Who knows, this event might be even prettier than what passed this morning.

On Saturday morning, August 23rd about 30-45 minutes before sunrise, the thin, waning lunar crescent joins Jupiter and Venus in a stunning triangle of loveliness in the eastern sky.The threesome will all fit inside an 8° circle.

Now that I know this is coming I don’t feel so bad about missing the conjunction.

Inspiration for Monday’s bright planet conjunction

Venus (top) and Jupiter this morning August 17, 2014 around 5:30 a.m. local time from Königswinter-Heisterbacherrott, Germany. The pair were a little more than a 1º apart at the time.
Click to see more images. Credit: Daniel Fischer

I tried this early this morning and all day to spot Venus and Jupiter before their tight conjunction tomorrow morning. I failed. But others had better skies or were more persistent. So just to whet your appetite for the BIG EVENT tomorrow, here are a couple views of the two planets ‘warming up’ before their act.

Jim Schaff of Duluth, Minn. found a brief break in clouds this morning August 17 to capture the pair of planets before sunrise. Tomorrow morning they’ll be three times closer! Credit: Jim Schaff

Jupiter and Venus cozy up for year’s best conjunction

The sky’s two brightest planets, Jupiter and Venus, will approach with 0.3 degrees of each other in morning twilight on Monday August 18th, the closest conjunction of the pair visible over North America since April 1998. This view faces northeast about 40 minutes before sunrise. Stellarium

As Mars approaches Saturn at dusk, Jupiter and Venus are zeroing in on each other at dawn for a spectacular close conjunction Monday morning August 18th. You won’t want to miss this one.

Conjunctions of the two brightest planets occur about once every 13 months but vary in visibility (some happen in daylight) and separation. The closer they get, the more arresting the view.

Tomorrow morning the planets will be a little more than 1º (two full moon diameters apart) – righteously close. But Monday morning they’ll be three times closer, just 0.3º  apart or a tad more than a half moon. That’s cozy enough for both to comfortably fit in the same field of view of a telescope.

Want to watch the approach? This view shows the sky tomorrow morning Sunday August 17th about 45 minutes before sunrise facing northeast. Venus will be about a degree above Jupiter and shine six times brighter.  Stellarium

To watch the event, find a place with a wide-open view to the east as far down to the horizon as possible.

Both planets will about 8º high or just shy of a fist held at arm’s length 40-45 minutes before sunrise.

Bring your camera too! A mobile phone might do OK in twilight, otherwise set your camera’s ISO to 400, place it on a tripod and open the lens to f/4 or 4.5. Then in auto mode, focus your lens at infinity by pointing it at the moon or a cloud. Now click your lens back into manual focus mode and point it at the planets, making a series of exposures from 1 second to 10 seconds. Check the camera back to make sure you’re in the ballpark on both sharpness and exposure.

Jupiter (top) and Venus in a more distant conjunction on June 30, 2012 seen over Lake Superior in Duluth, Minn. Credit: Bob King

Close as Jupiter and Venus will be for North America, skywatchers in central Europe will see them even closer (0.2º) before sunrise. After Monday, Jupiter continues its swift rise in the eastern sky while Venus slowly sinks toward the sun. They won’t pair up again until June 30, 2015 when they’ll be just as close in evening twilight in the constellation Leo.

Venus and Jupiter will pair up right next door to the Beehive Cluster in Cancer Monday August 18th at dawn. This shows an approximate binocular view. Stellarium

One final and happy note. Not only are the planets pairing up, they also happen to be right next to the Beehive star cluster in the constellation Cancer the Crab. I think you’ll need binoculars to see the cluster clearly, so be sure to have a pair along.

It should be a fun morning. The only down side is that it’s a Monday, meaning you’ll need a nap by the afternoon.

Seven tiny specks snared by Stardust likely souvenirs from the stars

Dust particle and its track captured in aerogel by NASA’s Stardust spacecraft in 2004. Credit: NASA

NASA’s Stardust spacecraft did more than snare dust samples of Comet 81P/Wild during its January 2004 flyby. It also caught at least seven fluffy flakes of interstellar dust – microscopic bits of matter exhaled by dying stars that salt and pepper the great open spaces across the Milky Way galaxy. If confirmed, these would be the first grains of matter gathered from outside the sun’s domain.

A team of scientists has been combing through the spacecraft’s aerogel and aluminum foil dust collectors since Stardust returned in 2006. Stardust’s main mission was to collect and return dust from Comet 81P/Wild during its January 2004 flyby, but twice during its 7-year, 3-billion-mile journey, the probe opened up the opposite side of its collectors to gather particles from the direction of the interstellar wind.

A researcher examines dust-collecting aerogel blocks carried by Stardust. Credit: Andrew Westphal, UC Berkeley

As the sun orbits around the center of the Milky Way at 450,000 mph (720,000 kph), material from interstellar space enters the solar system from a particular direction at high speed. Stardust sampled this ‘headwind’ and fortunately snagged a few specks of interstellar dust compared to the more than a million comet particles captured by the other end of the detector.

Artist’s impression of a red giant star blowing out gas and dust. Material lost by aging stars and supernovae may have been captured by NASA’s Stardust mission. Credit: JAXA/ISAS/LIRA

The seven particles probably came from outside our solar system, perhaps created in a supernova explosion millions of years ago and altered by exposure to the extreme space environment. Two of the grains are ‘large’ (1/32,000 of an inch across) and have textures resembling fluffy snowflakes. They contain a magnesium-iron-silicate mineral often found in meteorites called olivine, indicating the material didn’t come from the spacecraft or its collector trays. Dust grains containing these minerals are known to condense in the atmospheres of red giant stars.

This wasn’t scientists’ first encounter with ancient star dust. So-called pre-solar grains, material spewed by previous generations of stars that was gathered by gravity and reworked to form the sun and planets, have been found in very small quantities in meteorites. What Stardust collected are the first contemporary shards of stars blowing across our bow.

Because of their size and number, they’ve been extremely challenging to examine in the laboratory. Scientists caution that additional tests must be done before they can say definitively that these are pieces of debris from interstellar space.

Aerogel’s light and porous structure makes it perfect for capturing fast-moving particles without damaging them. It looks like smoke and feels like Styofoam to the touch. Credit: NASA

Despite barreling in at speeds up to 36,000 mph (54,000 kph), all but one of the particles survived, safely captured by the smoke-like cushion of aerogel. Two were discovered within the aerogel, four had burrowed into the aluminum foil separating the collector trays, and one was traveling so fast it vaporized as it tore through the gel. Three of them contained sulfur compounds, which some astronomers have argued don’t occur in interstellar dust. But who knows?

Supernovas, red giants and other evolved stars produce interstellar dust, water vapor as well as atoms like oxygen and nitrogen and other compounds necessary for life. The two particles captured in the aerogel go by the names Orion and Hylabrook.

Track of the Orion interstellar dust particle in aerogel. Crdit: D. Frank/NASA/JSC

Researchers expected the specks to be little more than formless blobs of material with little structure after being hammered by cosmic radiation, but they were both larger and more complex with their crystal structures intact. They’ll perform further tests to determine the amounts of different forms of oxygen called isotopes within their minerals, which could confirm their interstellar origin.

NASA got help from over 30,000 citizen scientists called “Dusters” in tracking down these particles and many more from the Stardust mission. If you’d like spy some specks yourself – including a shot at potential interstellar crumbs – stop by the Stardust@Home site.

Source

Comet 67P/C-G comes alive in 3D – Must see!

Beg, borrow or steal a pair of those cheap 3D red-blue anaglyph glasses and take a look at this photo. It’s made of two different images taken by Rosetta 17 minutes apart from a distance of 65 miles (103 km) on August 7, 2014. For the full effect, click to view the hi-res version. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

I was awestruck looking at this photo with just a pair of cardboard red-blue 3D glasses. Grab your pair and let your eyes climb over the foreground crags and onto the ‘neck’ joining the top and bottom lobes of the comet. A thick blanket of dust appears to cover the area. Did some spill from the spectacular range of cliffs above? And how about the boulders? Did they roll down the same cliffs?

One of the two images used to make the stereo image above. Click to enlarge. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Some of the crater-like depressions in the bulbous foreground lobe are filled with similar but smaller boulders while others liberally pepper the landscape. At front left, check out that huge jagged gash in the comet.

We’ve grown accustomed to detailed, close-up photos of planets and asteroids from our spacecraft and landers, but there’s something about seeing this comet in three dimensions that brings an alien landscape alive. It looks familiar in some respects, but strange and incomprehensible too.

Here are a couple more full-screen variations on the original stereo perspective: 1, 2

I’ve also selectively cropped several areas from the original image:

Boulders protrude from a smoother surface, while at left there appears to be a rockfall at the bottom of a cliff. Could ice flows have been active beneath the dust? Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Eroded crater with a craggy rim. Speculation only, but everything appears to be covered in dust. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Boulders collect on a smooth area of finer debris. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Rugged landscape of possible craters that have morphed in shape from erosion due to vaporizing ice. Rocks/boulders are everywhere! Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Mars and Saturn boogaloo with Zubenelgenubi

Mars and Saturn are now only about 7 degrees apart (a little more than three fingers) low in the southwestern sky at dusk. This view shows the sky about 90 minutes after sunset. Between the two, you can spot the dimmer star Zubenelgenubi, the brightest star in the constellation Libra the Scales. Stellarium

Evening planets Saturn and Mars are fading and dropping lower in the western sky as August ticks toward September. Remember when Mars was brighter than Arcturus this spring? Planets. They never sit still. Their light’s never constant. We love watching them change, which is why our ancient ancestors knew immediately they were different from the static stars.

From my house, I need to be vigilant to spot Saturn and Mars before they’re lost in the treetops. That means getting out about an hour after sunset in fading twilight and finding an open spot where I can look low in the southwestern sky.

You may have noticed that the two have slowly been drawing together over the past few weeks. Mars, much closer to Earth than Saturn, moves more quickly across the sky. It’s been ‘chasing’ slower Saturn for some time now.

Mars gets closer to Saturn with each passing night until August 25 when they’ll be in conjunction just 3.4 degrees apart (twice as close as tonight). Watching Mars move against much slower Saturn makes a fun and easy observing project. Stellarium

Tonight, the two planets will be 7 degrees apart on either side of Libra the Scales’ brightest star, Zubenelgenubi (zoo-BEN-el-je-NEW-bee). The name, a delight to pronounce, is pure Arabic and means ‘southern claw’. Libra’s stars used to belong to neighboring Scorpius and both it and nearby Zubeneschamali (northern claw) remind of us of times long ago when Libra belonged to Scorpius.

Zubenelgenubi (a.k.a. Alpha Librae) is a double star that observers with keen vision can split with the naked eye. Most of us will find that a pair of binoculars will make the job much easier.

Mars will soon pass its slower brother but not before the two are in conjunction and closest together on the evening of August 25th. Watching two planets pass in the night is fun and instructive – it makes us aware that everything in our solar system’s on the move.

This weekend we’ll look at another even more amazing planetary conjunction coming up very soon – Jupiter and Venus on August 18.