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.

How were the Perseids from your house last night?

Of five Perseids, only one was caught by the camera. It was an unusual meteor that flared twice before burning out. It almost looks like it skipped across the atmosphere like a stone skipping on water. Credit: Bob King

I set the alarm for 2:15 and spent an hour with the Perseids this morning. How many meteors flashed by? Oh, five. But every one was like winning the lottery.

The graph above shows the ZHR (Zenithal Hourly Rate), which is the number of Perseids an observer would see under a very dark sky with the radiant of the shower at the top of the sky. Counts are shown through 9 p.m. CDT Aug. 12. The trend toward maximum is obvious. Times are Universal Time. Subtract 4 hours for EDT, 5 for CDT, 6 for MDT and 7 for PDT. Credit: IMO

The low number was surprising given that magnitude 4 stars were readily visible. On the up side, all of those I saw were bright and moved incredibly fast like sparks from an arc welder. Preliminary data from the International Meteor Organization shows a peak around 55 meteors an hour yesterday evening (Aug. 12, U.S. time). Counts for the early morning hours still aren’t in yet, so final numbers and shower peak time may change.

Self-portrait with Perseids around 3:15 this morning. Perfect weather, friendly moonlight and cricket song made for a pleasant outing. At top you can see Auriga and the Hyades in Taurus. Credit: Bob King

A reminder that the Perseids will continue to fire off meteors through the remainder of the week, although at a declining rate. With the moon rising later each night, viewing conditions will improve, so be on the lookout for more flaming comet flakes.

Perseid meteors peak tonight!

Multi-photo composite showing Perseid meteors shooting from their radiant point in the constellation Perseus. Earth crosses the orbit of comet 109P/Swift-Tuttle every year in mid-August. Debris left behind by the comet burns up as meteors when it strikes our upper atmosphere at 130,000 mph. Credit: NASA

Ready for more celestial enjoyment after the weekend supermoon? Tonight’s the peak of the annual Perseid meteor shower, one of the year’s two best and most prolific meteor showers. The other, the Geminids, produces a few more meteors per hour but happens in the middle of December when the weather often puts a bite on nighttime activities.

Just two days past full, the moon rises around 9-9:30 p.m. and will be up all night, spreading its less than desired radiance across the sky. No question that fainter Perseids will be lost in the glare, but not the best and brightest. Under ideal conditions – a rural, moonless sky – more than 100 Perseids an hour flash across the sky. But with the moon out, expect closer to 25-30 per hour from a typical suburban location.

You can go out anytime to watch the shower overnight tonight (August 12-13), but you’ll see more meteors if you go out later when the radiant is higher in the sky. Higher is better because fewer meteors get cut off the observer’s horizon. Source: Stellarium

The key to seeing as many as possible is to keep the moon out of view. Set up your lawn chair to face northeast, north or southwest, kick back and wait for the meteors to come to you. Over the years, I’ve noticed that shower meteors often come in bursts. For 5-10 minutes you’ll see a handful or more and then all will go quiet for the next 5 minutes. Hang in there and I guarantee you’ll see at least some Perseids. You’ll now you’re see a genuine shower member if you can trace its path backwards toward the W of Cassiopeia near the location of the shower’s radiant.

Fireballs, those extra-brilliant meteors that shine as bright or brighter than Venus, are no strangers to this shower. Perseids are generally white and move swiftly, often leaving fading ‘smoke streaks’ or trains in their wake. These are hollow tubes of ionized air molecules that have been energized by the meteoroid particle’s passage. As they return to their original ‘relaxed’ or non-ionized state, we see a lingering afterglow.

Keep an eye on any really bright train. Some can linger for minutes and become distorted by upper atmospheric winds.

A Perseid burns up in Earth’s atmosphere photographed in orbit 250 miles up by astronaut Ron Garan on Aug. 13, 2011. The star Arcturus is directly above the meteor trail. Credit: Ron Garan / ISS Expedition 28 crew / NASA

Most meteor shower particles range in size from a small pebble to beach sand and generally weigh less than 1-2 grams or about what a paperclip weighs. They’re fluffy and porous material shed by comets. The main reason something so insubstantial can create such a striking flash of light has to do with its kinetic energy or energy of motion. Perseids scream into the atmosphere at an average speed of 130,000 mph (209,000 kph).

Even a tiny bit of mass can make a big, bright display when it hits the air at such tremendous speed. Think of the difference between being hit by a slow-moving vs. a fast-moving baseball. It stings either way, but the fast one’s worse by far.

Hopefully your weather will be clear tonight. If so, spend an hour with the shower. You’ll see a smattering of meteors in the early evening and more as the night grows long and radiant rises higher. Let us know how you fare in words and pictures (my e-mail: rking@duluthnews.com), and I’ll share your observations in an update tomorrow.