Dwarf star Wolf 359 endures after fictional Borg battle

Wolf 359 photographed several years apart so you can see its movement across the sky. The star travels 0.4 arc seconds per year – the moon’s diameter in 4,500 years – against the distant starry background. Credit: ESO, Digitized Sky Survey, U.K. Schmidt Telescope, PPARC and the Association of Universities for Research in Astronomy, Inc. (AURA).

The Borg were probably the most frightening and evil of all the alien races in Star Trek: The Next Generation. Outside of their collective group, nothing mattered. It was just kill, kill, kill and assimilate. If you were captured, the Borg hooked you into the network, sucked every thought from your brain and used the knowledge to destroy the next heroic attempt to snuff them out.

A famous fictional battle took place between the good guys and the Borg happened in the year 2367 near the star Wolf 359. Why Wolf 359 was chosen I don’t know, but it is a real star and a special one at that. Perhaps the writers wanted a star near Earth to bring home the impending threat to our own solar system.

Wolf 359 is a very faint star located in the southern half of Leo the Lion. This map shows the sky facing east in late Jan. – early Feb. around 9 p.m. local time. Created with Stellarium

Wolf 359 was the 359th star of more than a thousand found discovered by German astrophysicist Max Wolf to have a large motion across the sky, what astronomers refer to as proper motion. All stars are moving around the center of the Milky Way galaxy. Nearby stars generally appear to move more quickly across the sky than distant ones because they’re closer to us. Kind of like driving along the freeway where a service station quickly recedes into the distance while the distant mountain ahead appears nearly still for many miles.

Astronomers are able to measure distances to stars with large proper motions, and once you know distance, you know how big and bright a star really is. What we learn from them can then be applied to more distant stars, the movements of which are nearly impossible to detect. That’s why Wolf cataloged as many of these stellar midges as he could.

The size of our sun and Wolf 359 compared. Illustration: Bob King

Outside of the sun, Wolf 359 is the third closest star to Earth after the Alpha Centauri system and Barnard’s Star. Just 7.7 light years away, it’s one light year closer than the sky’s brightest star, Sirius. You’d think something so close would outshine Sirius or at least be visible with the naked eye. I wish. Wolf 359 shines at a paltry 13.5 magnitude, requiring at least an 8-inch telescope to see.

Unlike Sirius, which is both hotter and nearly twice as large as the sun, Wolf 359 is a red dwarf only about 16% the size of the sun or approximately 140,000 miles across. That’s hardly twice the size of Jupiter. If Wolf 359 were at the center of our solar system, you’d need binoculars to see it as a disk. Not only that, but with an energy output of 1/10th of 1% of the sun, it would only be as bright as ten full moons squished into a tiny dot.

Astronomer Max Wolf

Red dwarfs are red because their surfaces are cool, and like an ember, emit more red light than green or blue. They’re also small. Wolf 359 is about as small as star can be and still fuse hydrogen atoms together in its core to create energy the way the sun does. Its surface cooks at at a tepid 4,000-4,700 degrees F, cool enough to allow molecules like water and carbon monoxide to form. You won’t find that happening on old Sol.

Despite its diminutive persona, Wolf 359 will outlast the sun and nearly every star we see in the night sky. Being cool, red dwarfs burn their hydrogen fuel frugally compared to larger stars that devour theirs at prodigious rates. Not only that, but hydrogen is continually recycled throughout the interior of red dwarfs and available for burning. In sun-sized and larger stars, hydrogen is converted into helium ash, which settles in the core. The sun will continue to burn hydrogen in its old age, but only in a thin shell around the core.

When the sun runs out of fuel in another 5 billion years and evolves into a white dwarf star, Wolf 359 will keep the home fires burning for up to 10 trillion years. No matter what happens in science fiction, Wolf 359 will endure.

Comet Lovejoy rages against the dying of the light – updated

Comet Lovejoy shows a brilliant coma and a tail several degrees long in this photo taken by SOHO at 10:30 a.m. CST today. Click photo to see the latest video. Credit: NASA/ESA

(If you’ve been here earlier, please scroll up for the latest videos and photos showing Comet Lovejoy zip past the sun. Very exciting stuff.)

Wow, that is one brilliant comet! The huge spikes in the head are caused by saturation (overexposure) of the image detector by the intensity of the sunlight reflecting from Lovejoy’s head or coma. I’m reminded of a Klingon Bird of Prey warship from the Star Trek TV series or better, the Thunderbird, a Native American symbol of power and strength.

I suspect some will attempt to see Comet Lovejoy today even though it’s extremely close to the sun. I’m aware of at least two tries by experienced amateur astronomers this morning using binoculars and a 16-inch telescope with negative results. If you’re thinking about doing this yourself, be very careful. The comet is only two degrees away from an object that if stared at can damage your vision for life. The only safe way to make an observation is to completely block the sun with a solid, opaque object like a building, power pole or roof and stare into the sky glare with sunglasses.

Closeup of the comet from the STEREO-A space telescope from yesterday. Credit: NASA

If you’re observing around local noon in the mainland U.S. and Canada, the comet will be below and left of the sun. In the mid-afternoon, Lovejoy will appear almost directly above the sun, even closer and probably impossible to see no matter how bright. Your safest route to keep tabs on the comet’s flight is by checking the LASCO C3 and LASCO C2 real-time photos. As of 1 p.m. CST, it’s about as bright as Venus or magnitude -4.

Take a close look at the picture above and you’ll see two tails. The brighter, shorter one to the right is the dust tail, formed of cigarette-smoke-sized dust particles shed from the vaporizing comet’s nucleus. The dust reflects light strongly. Farther up along the left side of the dust tail is a fainter, spike-like ion tail caused by atoms fluorescing in ultraviolet sunlight.

The photo at left was taken at 5:36 p.m. CST Dec. 15 with SOHO's closeup C2 coronagraph and shows the comet near the time of closest approach to the sun. At right are pictures of the two comet fragments that preceded Lovejoy and might be related to it. One developed a short tail; the other had a star-like appearance. Credit: NASA/ESA

You’ll also see two very tiny additional cometary fragments in the video link. Both precede Comet Lovejoy and look like stars. The first one is visible straight below the sun before Lovejoy moves into the frame  on 12/13 around 14:18 on the clock. The second is immediately above the comet on 12/15 around 7:30.

This photo, taken at 6:46 p.m. CST Dec. 15 by the Solar Dynamics Observatory, is one frame of a short movie. At least a part of the comet appears to have survived perihelion. Click image to see the video. Credit: NASA

Altogether an amazing sight, but will it survive its hairpin turn around the sun when it reaches perihelion (closest approach) this evening? Indeed it may have as you can see from the picture above. I’ll update with the latest, so please check back. By the way, the today’s blog title is a reference to one of my favorite Dylan Thomas poems “Do Not Go Gentle Into That Good Night“. Click the link to hear him read it.


Even better, check out this color video from a different angle of the zooming comet after perihelion compiled from Solar Dynamics Observatory photos. Amazing!!

Catch the moon, Regulus and Mars in the eastern sky around midnight tonight. Created with Stellarium

There’s more than pygmy comets flying around the sun to see. After all, we have several hours of dark sky this evening before the moon rises around 10 p.m. Step out and enjoy the colors of twilight and watch Orion’s signature 3-starred belt come up in the east around 8. You’ll get an eyeful if you’re outside around midnight, when the waning gibbous moon rises right under Leo’s brightest star Regulus. A fist to the lower left will take you straight to the planet Mars.

Mars-Regulus flyby this week, too!

Mars inches along the bottom of Leo's Sickle in the coming mornings masquerading as a double star with nearby Regulus. Maps created with Stellarium

While you’re waiting for your shot at seeing asteroid 2005 YU55 , let’s talk about something most all of us will see with only a little effort. Tomorrow morning before dawn and for the next few days the planet Mars will shine within a degree or two of the bright star Regulus in the constellation Leo the Lion. The two will be closest on the mornings of the 10th and 11th, when they’re separated by only about 1.5 degrees.

In this wide view, we face east around 5 a.m. local time, when Mars, Regulus and Leo are well placed in the sky.

This is a fine opportunity for sky watchers to compare the two orbs’ colors and brightnesses. Mars is pinkish-orange and shines at magnitude 1.0, a tad brighter than white Regulus at magnitude 1.3. Regulus marks the end of the asterism called the Sickle of Leo which happens to look like a backwards question mark. The reason Mars gets so close to the star is because it lies almost exactly on the same “highway” in the sky called the ecliptic. This is the path the planets, moon and sun take through the 12 zodiac constellations.

An ostrich egg is a handful. It's also a good way to visualize the shape of Regulus. Credit: Mark Pellegrini

Although they appear similar except for color, the two couldn’t be more different. Mars is a small planet shining by reflected sunlight, while Regulus is 4.3 times the size of the sun and spins so fast – 200 miles per second – that its shape resembles that of an ostrich egg. Through a telescope, Regulus, like nearly every other star, is too far away to show its actual shape. Except for color and brightness, all stars look the same through most telescopes. When observed through a circular aperature, stars show only an Airy disk, a tiny bright spot surrounded by several delicate rings of light. The disk is not the star itself but rather the smallest, sharpest view of an object so distant its shape can’t be resolved.

Mars shows a bright, white north polar cap and a variety of dark markings when viewed through a medium-sized scope at high magnification. Credit: Damian Peach

Mars on the other hand will gladly oblige if you pump up your magnification to 150x and higher. Provided the air turbulence is low, you’ll spy a tiny ochre disk with a white dab at one end – that’s the north polar ice cap. It’s currently winter in Mars’s northern hemisphere and the ice cap is very prominent. Additional dark markings similar to the ones in the photo at right will be in view during the hours of 4-6 a.m. in the coming week.

Sharp-eyed observers will also notice that the planet’s disk is not a perfect circle but more like a gibbous moon. Except around the time of opposition, when it’s closest to Earth, Mars shows a slight phase effect, because we see the planet well off to one side of the sun-Earth-Mars line. From that angle, a bit of shadow or shading darkens an edge of the planet.

Mars is a breeze to see and should make a pretty sight so close to a similarly bright star. I hope you’ll have clear skies this week to enjoy the view.

Full Snow Moon shines tonight

A halo rings the moon last night. Halos are sometimes seen in advance of a weather front that brings rain or snow. Today we have light showers in Duluth. Photo: Bob King

I know, I know. Your calendars all show the full moon happening on the 18th. That’s technically true, but for many in the U.S, Canada and South America, the moment of fullest moon happens early tomorrow morning. For the Central time zone, this occurs at 2:35 a.m. Friday, much closer to tonight than tomorrow night.

With your naked eye tonight, the moon will look perfectly full. Only a good pair of binoculars or telescope will show the terminator, the crusty edge of the moon that separates the remaining sliver of lunar night from the sunlit portion. If you look closely Friday night, you should be able to see that the terminator has switched overnight to the right or western side of the moon, giving it a slightly shaved or out-of-round appearance.

This map shows the sky facing south around midnight tonight when the full moon will be highest in the sky. It's only a few degrees to the lower right of Leo's brightest star Regulus. Saturn and Spica will be well up in the southeast at the same time. Created with Stellarium

February is typically a snowy month in the north and east, but we’ve had warm weather here this week and lots of snow melt, so the Native American name for this month’s full moon – the Full Snow Moon – hardly seems appropriate at the moment. Of course there are still 11 days till March, plenty of time for a storm to blow by.

Stardust-NExt swings by Comet Tempel 1 earlier this week. Credit: Credit: NASA / JPL / Cornell / animation by Emily Lakdawalla

I know where it’s probably snowing right now – the nucleus of Comet Tempel 1. I stopped by the excellent Planetary Society blog, written by Emily Lakdawalla, and discovered a few new ways of looking at the comet I thought you’d enjoy. Emily created this dramatic flyby animation using 39 images from the recent mission.  There’s a larger version with 61 images on her site.

Scientists studying the man-made impact crater blasted out in 2005 found it more subdued than expected. Fresh craters usually have sharply-defined rims, but not this one.

According to co-investigator Peter Schultz that’s an indication of just how weak and fragile the comet’s crust is.  Bear in mind, when you look at Comet Tempel 1, you’re seeing a huge hunk of dirty ice, which resembles the blackened piles of snow that currently line our city streets. Comets are a lot colder than Duluth – hard to believe – and are composed of other ices like frozen carbon dioxide (dry ice) in addition to water ice.

To see comet Tempel 1 in 3D, slowly cross your eyes, trying to get the two pictures of the comet to overlap. Once they overlap in the center of your vision, bring your eyes into focus on the overlapped view, and it should appear three-dimensional. The image has been artificially colorized based on color images from the Deep Impact mission. Credit: NASA / JPL / Cornell / color composite by Daniel Macháček

If you can cross your eyes, you’re in for a 3D treat, because Daniel Macháček used the new photos of the comet to create a stereo image. Sit back about a foot from your screen and follow the instructions in the caption. You can also concentrate on the two white dots while you cross your eyes. When they merge into one, lift your gaze to focus on the comet.

Use a pair of red-blue glasses to see a 3D view of Comet Hartley 2 from last year's EPOXI mission. Credit: NASA / JPL / UMD / Daniel Macháček / Luca Cassioli

Need a bigger photo? Click HERE for an enlarged version. When it snaps into 3D, the middle of the comet will be in the foreground with the left and right sides receding into the distance.

Looking at these photos makes me really appreciate being around for the golden era of space exploration. Closeups of comets, Saturn’s moons, ancient riverbeds on Mars – you name it. We all could have been born in the 10th century, and while I’m sure there were cool things happening then, nothing compares to the bounty of the current day.

Say cheese!

Atlantis docked at the Mir space station on July 4, 1995. Credit: NASA

According to Spaceflight Now, when the space shuttle Discovery launches on February 24 and later docks with the International Space Station (ISS), shuttle managers are considering staging the ultimate “photo op”. They’d like to put a crew inside the Russian Soyuz craft, have them back off from the space station and take a photo of the ISS with the shuttle attached.

A similar staged picture was taken on July 4, 1995 by a Russian crew shortly before the shuttle Atlantis undocked from the Mir space station. Back then, two cosmonauts in a Soyuz capsule pulled back some 300 feet to take the photo you see above.

To create the defining image of the space station and shuttle, we’ll need Russian approval and cooperation. Hopefully that will come soon. As a photographer, I’d hate to see a great opportunity go wasted.

When it’s time to touch the shutter button, can’t you just picture the moment? Assuming the photographer has a sense of humor, he or she may call out those familiar words: “Say cheese!” Russians ask their photo subjects to say the same phrase as we do in the U.S., but their word for cheese is сыр and pronounced sir.

While the ISS is currently making daytime passes only for the region, it will return to the evening sky starting on the 20th – just in time to follow the shuttle Discovery when it docks with the station later this month.

The waxing gibbous moon steps into a hexagon of bright company tonight. View facing south around 8 o'clock. Maps created with Stellarium

The weather forecast for the Duluth region looks partly cloudy this evening. Good! Take a look outside at the moon because it will add its own pizzazz to the party of bright stars called the Winter Hexagon. Matter of fact, it’ll be surrounded by them. If you’re looking for an excuse to get out for some fresh air, none is better than a walk in the company of all that celestial sparkle.

The Hexagon is an enormous figure, spanning from near the top of the sky at Capella all the way down to Sirius in the south.

Last night I could easily see the Big Dipper and constellation Leo the Lion even in bright moonlight. Since the weather is warming up a bit, why not pop your head out for a look around 9:30-10 p.m.

Leo is easy to find using the Big Dipper's Bowl. It's composed of two widely-separated halves: the Sickle at top and the triangle-shaped tail below. The view shows the sky facing east around 9:30-10 p.m.

The Dipper stands on its handle in northeastern sky. To find Leo, simply make a fist and thrust it at the Bowl. Three fists to the lower right will take you to the Sickle or ‘Backwards Question Mark’ that forms the head of the lion. Regulus is the bright star at its base. Now drop down about a fist to the lower left of Regulus and you’ll see a triangle of stars that represents the lion’s tail.

What could be easier? Leo, like Hydra the Water Snake, is one of those transitional constellations that straddles two seasons, winter and spring. With the temperature predicted to best 40 degrees today, you might feel inspired to follow the tracks of the lion tonight.

Sundog mystery explained

A faint halo, sun pillar and an upper tangent arc (top) appeared for a brief time around 8 a.m. today around the sun. Photo: Bob King

Hexagons. Bees build them out of wax. A snowflake’s beauty is based on their floor plan. Every time you pick up a pencil you hold one. This morning, they were at it again, when hexagonal ice crystals created a halo and sun pillar display around the sun.

Three different phenomena were happening, but all were created by sunlight refracted through or reflected off of 6-sided, columnar ice crystals shaped like very tiny pencils. Halos are fairly common and occur when a light ray is bent or refracted as it passes through one side of a crystal and emerges at an angle out the other side. Millions of crystals all doing the same thing concentrate the sun’s light into a circle with a radius of 22 degrees (44 degree diameter).

Light reflecting from the undersides of hexagonal, plate-like crystals gives rise to sun pillars. Credit: Keith C. Heidorn

The same crystals form the upper tangent arc, but only the ones that are horizontal or parallel to the ground. Sunlight glinting off the undersides of hexagonal, plate-shaped crystals falling parallel to the ground create the vertical streak of light or sun pillar.

By the time I got back to the house from walking the dog, the clouds had changed and all of it went away. You never know when nature, always unmindful of human scheduling, will unveil something out of the ordinary.


Watch the sundog (at right) disappear in a flurry of shock waves as the rocket rises. At left, keep an eye for a streak of light to form and fade.

Halo phenomena and in particular sundogs were in the news again late this week when atmospheric optics expert Les Cowley cracked the mystery on why the rocket that launched the Solar Dynamics Observatory (SDO) “destroyed” a sundog on its way to orbit.

Each of these sundogs comes with its own tail. Photo: Bob King

Sundogs are brilliant, round patches of light on either side of a solar or lunar halo, and they form by light refracted by those plate-shaped hexagonal ice crystals. When the rocket was launched on February 11, 2010 and rose through a layer of cirrus clouds, shock waves disturbed the ice crystals causing a multi-colored sundog to completely disappear. At the same time, a streak of cloudy light appeared alongside the rocket.

Cowley and colleague Robert Greenler at first thought that randomly-distributed crystals might be responsible for the streak, but that didn’t jive with their computer models. Then they realized that the crystals were organized by the shock waves into a “dancing army of spinning tops” that in unison produced a small halo around the rocket itself.

A simulation of a hypothetical halo around the SDO rocket last February. Credit: Science@NASA

The streak you see in the video is only part of a hypothetical halo around the rocket. “This could be the start of a new research field—halo dynamics,” said Cowley. To learn more about this interesting new phenomenon, please check out this NASA release.

One last tidbit: Algol, the “Demon Star” in Perseus we visited in a blog earlier this week, will be up to its old tricks again this evening. It’s at minimum light at 6:07 p.m. Central time, which means if you go out when it first gets dark, it will shine at its faintest. Take a look again around 8 or 9 o’clock and the star will have returned to normal brightness. Very easy to see!

Starry pleasures either side of midnight

The pentagon-shaped constellation Auriga (Awe-RYE-guh) is up for easy viewing around 7 p.m. local time. Its brightest star is Capella. To its right are three stars in a skinny triangle nicknamed "the Kids". Aldebaran, Taurus' brightest star, is about "one fist" to the right. Maps created with Stellarium

There are those who watch and study the stars and planets during evening hours and those who prefer the morning hours for their cosmic connection. Today we’ll try to provide something for sky watchers on both sides of the midnight hour. And if you feel like switching sides or attempting to do both, have at it.

One of the season’s easiest constellations to identify is Auriga the Charioteer, which made the list of the original 48 ancient constellations described by the 2nd century Roman astronomer Ptolemy. Before Orion rises and steals all the thunder, go outside after dinner and face northeast. If you stick your fist out at arm’s length and look about three “fists” above the horizon, you can’t miss the white, twinkly spark Capella. It’s the brightest star in Auriga, a constellation shaped like a pentagon and spanning a bit less than two “fists” end to end. The figure of Auriga is depicted holding a chariot’s reins, but oddly, no chariot is outlined among his stars. Capella is a Roman name meaning “she-goat” after the goat Amaltheia that suckled the infant Zeus. Nearby are three fainter stars in a snug triangle – these are Amaltheia’s kids, or simply, “The Kids”.  The bottom right star of the pentagon used to be shared between neighboring Taurus the Bull and Auriga, but when firm constellation borders were set by the International Astronomical Union (IAU) in 1930, it was assigned to Taurus as the star Beta. You may feel free, like I do, to still include it in Auriga to preserve the group’s geometrically-satisfying pentagonal outline. Just don’t tell the IAU.

When we look toward Auriga, we’re peering out to the outer rim of the Milky Way galaxy. Fewer stars pack the spaces between us and the rim compared to looking the other direction toward the galaxy’s hub. You’ll find the Milky Way dim here but not totally lacking. Take your binoculars and point them into the center of the pentagon. Among the individual stars across the field of view, you might stumble upon two or three denser clumps – the star clusters M36 and M38 – that we’ll examine more closely in an upcoming blog.

Leo stands high in the south tomorrow morning at the start of dawn. The third or last quarter moon joins Regulus, while the trio of Venus, Spica and Saturn catch the eye in the southeastern sky.

If you prefer starry mornings or just happen to be up tomorrow around 6 a.m., part the curtains and look south. There you’ll see the last quarter moon in conjunction with Leo the Lion’s brightest star Regulus. That’s not all. Look to the southeast for a trio of two bright planets – Saturn and Venus – and Virgo’s brightest star Spica.