Our first full moon this month occurred on December 2, and tonight it returns for an encore. Watch for the Blue Moon to rise up in the northeastern sky in the constellation Gemini.  One outstretched fist to the left are Castor and Pollux, the two Gemini twins and the brightest stars in the constellation. Created with Stellarium.

So will the moon be blue tonight? Only if you pay it no attention. Look up during the New Year’s revelry and loft your glass to the shining face of night’s faithful companion. I’ve heard so many references to this year’s Blue Moon how could I pass up adding my grain of soil to the anthill of commentary? Most months have only a single full moon because a complete cycle from one full moon to the next takes 29.5 days. Only if a full moon lands on the first or second day of a 30 or 31-day-long month will there be enough time to squeeze in a second full moon 29.5 days later. December ’09 had room to spare.

Blue moons occur every 2.5 years but a blue moon on New Year’s Eve is a bit more unusual. This last happened in 1990 and won’t happen again until 2028. The name Blue Moon has more to do with farmers and calendars than with color. Each of the four seasons normally has three full moons or one per month. Back in 1937, the editor of the Farmer’s Almanac of Maine used the term Blue Moon to describe the third full moon in a season that had four full moons. Then in 1940s, an astronomy writer misinterpreted the seasonal context and described a Blue Moon as the second full moon in a month. It stuck.

If you live in the U.S. and you’re reading this around the lunch hour today, you might be interested to know that the moon is in partial eclipse right now (see below) for people living in Asia, Africa and Europe where the sky is dark. Don’t feel too badly about missing it. Only 10 percent of the moon will dip into Earth’s inner shadow, not much as eclipses go. To see a fine animation of how the moon moves through our planet’s shadow during this particular eclipse, please drop by the Shadow & Substance homepage. The author also has a very nice animation of Mars in retrograde motion, a topic we looked at last week. As for upcoming lunar eclipses, there will be a partial one on June 26, 2010 visible from the western U.S. and a total lunar eclipse for all of the country on December 21.

A partial lunar eclipse is seen behind light decorations in Macedonia’s capital Skopje, on New Year’s Eve, Thursday, Dec. 31, 2009. Credit: AP Photo/Boris Grdanoski

Upper Midwest skies are forecast to be clear to partly cloudy tonight. As you gaze through the billows of your breath in the frosty air, who knows but you might just see a tinge of blue to that old moon after all.

With all the astronomers, telescopes and robotic probes making discoveries at a furious pace, it wasn’t easy to narrow the list to just ten stories this year. We’ll start with #10 and end with what I consider the top story of 2009. A list is always an arbitrary thing so if I missed an important one, please let me know! 

#10 – Naked eye comet Lulin sports two tails. Lulin was the year’s best comet and displayed two tails, a typical one (poking out on the right) and a second or anti-tail pointing the other way toward the sun. These photos were taken on Jan. 31 (top) and Feb. 4 by Joseph Brimacombe of Cairns, Australia. In the bottom frame, the right-side tail broke off the comet in a tail disconnection event. Like a lizard, a new one will grow back in its place.

#9 – Evidence of volcanic activity on Mercury. What looks like a large gouge in the big crater just above center is known as a pit crater. These unusual craters were photographed during this fall’s Messenger spacecraft flyby of the planet Mercury. Pits may have formed when subsurface magma drained elsewhere and left a roof area unsupported, leading to collapse and the formation of the pit. This one has multiple floors, suggesting that volcanic activity was widespread in the geologic evolution of Mercury’s crust. Credit: NASA

#8 – Cassini sees fine structure in Saturn’s rings. Saturn’s rings were edgewise to the sun this past September. Around this time, the sun barely cleared the horizon from the rings’ perspective. The Cassini probe photographed clumped-up material within the rings casting long shadows in the low light. Astronomers believe the clumps form, break apart and reform in a dynamic process. Credit: NASA/Cassini imaging team

#7 – First detailed photos of the Apollo landing sites. The new Lunar Reconnaissance Orbiter orbits close enough to the moon’s surface that it was able to resolve details of the Apollo landing sites. Message to Apollo landing hoaxers: please sit down and eat your healthy serving of crow. Credit: NASA

#6 – First definitive evidence of an ancient lake on Mars.The ancient shoreline and lakebed of Shalbatana Lake on Mars (left photo), and an artist’s view of what the lake may have looked like 3.4 billion years ago. Scientists have found evidence of beach deposits in the form of ridges and troughs in what is now a dry lakebed and delta. Credits — Left: G. Di Achille, University of Colorado. Right: NASA/JPL/Univ of Arizona

#5 – New largest ring ever discovered around Saturn. Saturn’s new ring is a behemoth! The planet and its familiar rings are just a blip at the center of the new ring which is 13.4 million miles in diameter and composed of fine dust and ice. While faint visually, the ring gives off a faint glow of infrared or heat energy that the Spitzer Space Telescope could see. The ring was likely created by comets and meteorites bombarding Saturn’s moon Phoebe and kicking up material into space. Credit: NASA

#4 – Asteroid / comet impact near Jupiter’s south pole. First seen and photographed by Australian amateur astronomer Anthony Wesley on July 19. No one saw the moment of impact but soot-like materials and heat were detected in the spot which appeared out of nowhere on July 19. This is only the second time an impact has been recorded on Jupiter. Credit: NASA/ESA

#3 – Gliese 581e, the lightest extrasolar planet discovered. Astronomers are inching ever closer to finding planets more like the Earth than Jupiter. The star Gliese 581 (right) is located 20.5 light years away in Libra the Scales and has a remarkable system of four planets including Gliese 581e (foreground), which has a mass only 1.9 times that of Earth. It’s likely composed of rock like our planet. Gliese 581d is more massive but lies within the habitable zone around the star where liquid water could exist on its surface. Credit: ESO/L. Calcada

#2 – Sun at deepest minimum in almost 100 years. At left is what the sun looked like for much of 2009: no spots! At right is the sun near solar maximum with numerous sunspot groups which often harbor explosive flares. The lack of spots and solar activity has a cooling effect on Earth’s upper atmosphere; it’s also the reason for the downright dearth of northern lights the past two years. Credit: NASA/ESA

#1 – Water discovered on the moon. The LCROSS mission (Lunar Crater Observation and Sensing Satellite) sent a rocket stage crashing into a permanently-shadowed crater near the moon’s south pole on October 9. The resulting plume was observed and analyzed by the LCROSS craft and other satellites before LCROSS impacted the moon, too. Scientists found evidence of relatively abundant water within the plume. Astronomers believe the water – in the form of ice – comes from long-ago comet impacts. Credit: NASA

Illustration: Bob King

Like the planets, I’m traveling today and can’t stop for very long in one place. Highlights in the coming week include Mars in retrograde motion (moving to the west instead of east) and the moon passing by Mars the day after New Year’s. Jupiter is hurrying out of the evening sky while edging toward Aquarius, its next new home in the zodiac.

Stop by tomorrow when we’ll take a look at the my picks for the Top Ten astronomy stories (and photos) of the year.

Andrew Kirk of Bishop, Calif. shot this photo last week of the first-quarter moon through a bit of architecture. The moon tonight will be near the Seven Sisters cluster. Credit: Andrew Kirk

The waxing gibbous moon will pass through the southern portion of the Seven Sisters star cluster this Monday evening. Just as the sky gets dark around 6, the cluster, also known as the Pleiades, will lie immediately to the left of the moon. Between 6:30 and 8 p.m. the moon will slowly cover or occult a number of cluster stars but just miss the brightest ones which form a small dipper shape (right). That’s how we’ll see it in the Upper Midwest.

Because the moon is relatively near the Earth, the path it takes through the cluster will vary depending on where you live. Atlas will be occulted for sky watchers in the southern half of the U.S. while those further southeast will be able to watch the bright Pleiads Alcyone and Merope occulted. For viewing times for your location, please visit this website. The times listed there are Universal time (UT). To convert UT to U.S. times, subtract five hours for Eastern, six for Central, seven for Mountain and eight for Pacific.

The moon takes its time moving through the dipper-shaped Seven Sisters cluster. The left image shows its position at 7 p.m., the right at 8 p.m. Use binoculars to watch the event. Illustrations created with Chris Marriott’s Skymap software.

The Seven Sisters will probably be very hard to see with the naked eye because they’ll be overwhelmed by the glare of the nearly full moon. To enjoy the event it’s best to use use binoculars. It’s a very pretty scene when the moon floats so close to so many bright stars. A small telescope will show the actual occultations of individual stars best.

The brightest stars in the Seven Sisters cluster are labeled in this photograph. Atlas will nearly touch the northern edge of the moon for Duluth at about 7:53 p.m. Alcyone and Merope will be covered for the Georgia, the Carolinas and Florida, among other states in the southeast. Credit: John Lanoue

While you’re out watching the moon, see if you can identify four of its most prominent craters shown on the photo/map below. The trio of Copernicus, Kepler and Aristarchus are always a real standout. Each has its own system of bright rays created by the rain of material back to the surface after the impacts that excavated each of them. Photo from Stellarium.

A snowman made by my daughter’s boyfriend reflects the light of the 10-day moon last night. Taking time exposure photos on a tripod by moonlight can make night scenes appear as bright as day. The three bright objects across the top of the frame are (from left): Mars, Procyon and Sirius. Details: 16mm lens at f/2.8, 25-second exposure at ISO 800. Photo: Bob King

Can you tell the days are getting longer? I didn’t think so. But there’s no question the nights are getting brighter. As the moon waxes toward full and reaches the apex of its arc through the zodiac this week, lots of sparkly evenings are in the offing. Between first-quarter and full moon phases during the winter months, the moon’s monthly path takes it near the top of the sky. Tonight you’ll find it in Aries the Ram and Monday in Taurus the Bull. Moon shadows will be as short as those cast by the sun in summer. No surprise there: this coming week’s full moon will be in the same place in the sky as the sun was last June.

The constellations of summer brought us their share of delights but now they’re "on vacation". Sagittarius, Scorpius, Libra, Ophiuchus are only up in the daytime, basking in sunlight and hidden from view. There is one summer curiosity in Ophiuchus very low in the west during the early evening hours. It’s Voyager 1, the most distant human-made object from Earth. The probe was launched on a mission to study and photograph the planets Jupiter and Saturn back on September 5, 1977. After a Saturn flyby in 1980 and a final look back for a solar system portrait in 1990, the probe began its new mission: to explore the fringes of the solar system and interstellar medium.

The sun sends a constant stream of thin, hot, electrically conducting gas into space called plasma. More commonly referred to as the solar wind, the stuff blasts across space at hundreds of miles per second. The wind forms an enormous bubble called the heliosphere that extends billions of miles beyond the farthest planets and asteroids. Near the boundary of the heliosphere, the gas slows down as it begins to feel the presence of the interstellar medium, a thin soup of dust and gas between the stars. This boundary is called the termination shock.

The sun’s gravity as well as its electric and magnetic bubble called the heliosphere define its region of influence in the Milky Way galaxy. This bubble protects the Earth and other planets from many potentially dangerous cosmic rays, which are high speed particles careening around the galaxy that can damage cells and DNA. Illustration: Walt Feimar/NASA

Both Voyager 1 and its sister probe Voyager 2 have crossed the termination shock and are now within the heliosheath just a few years travel away from the outer boundary of the sun’s influence called the heliopause. Beyond the edge of the heliopause lies interstellar space. If all these terms seem a bit confusing, consider your faucet. Turn the water on full blast and watch what happens when it hits the sink basin below. You’ll notice a smooth circle of streaming water surrounded by a zone of turbulent bubbling. The area within the circle corresponds to the sun’s flowing plasma, the circle’s edge mimics the termination shock and the turbulent water beyond is the heliosheath, where the Voyagers are now.

The sun’s sphere of influence follows a pattern similar to water pouring into a kitchen sink. You’ll notice that the water suddenly slows down when it hits the termination shock boundary. So does the real solar wind, dropping from hundreds to just 30 miles per second. Photo: Bob King

Voyager 1 is currently 10.5 billion miles from the sun and traveling at 10.5 miles per second. When you consider that it takes a radio transmission traveling at the speed of light 15.6 hours to reach Earth from the probe you begin to realize how far away that little machine really is. Pluto, which has always served as a metaphor for deep distance, is considerably closer at 3 1/2 billion miles or 5.5 light hours away. Voyager 1 has enough power to continue to function and send data back until about the year 2020 by which time astronomers hope it crosses the final boundary and samples what’s between the stars. The electricity to run the instruments all these 32 years comes from the heat produced by the radioactive decay of plutonium. Heat is converted into electricity in a special generator.

The outbound paths of four spacecraft currently heading out of the solar system. To keep tabs on their distances check out this link, which has lots of additional information. More about the Voyager probes can be found in this Voyager Q&A. Credit: Wiki

While Voyager 1 holds the distance record, it and several other craft will head toward the stars after they pass through the heliopause. In the year 40,272 the probe will pass within 1.7 light years of a minor star in the Little Dipper called AC+79 3888. Voyager 2, presently in the constellation Telescopium, is headed toward another obscure star in Andromeda.

These emissaries of our civilization may outlast our species for all we know. They’re a high-tech version of a message in a bottle. Each carries a gold record and playback stylus containing music, greetings and sounds of Earth should any extraterrestrials happen upon them.

The probes have made many discoveries about the fringe of the solar system during their long journey. Most recently the Voyager probes discovered a strong magnetic field in a nearby cloud of interstellar matter that lurks just beyond the heliopause. Click here to learn more about the find.

When I fall asleep at night I sometimes like to imagine things that continue to be active during my slumbers like a favorite river or waterfall or the slow vaporization of Mars’ north polar cap under the spring sun. It’s fun and oddly inspiring to think about things beyond one’s immediate world . Perhaps it’s time I add Voyager 1 to that list.

Merilla Guillen of Duluth lifts a heavy shovelful of snow as she tries to clear her driveway of snow left by the plow for the second time Friday afternoon. Photo: Bob King

Wow, that was a lot of snow and slush that came down from the sky! Those of you reading this in the Midwest are probably as weary as I am from shoveling. Because the snow fell at a temperature around 32-33 degrees, it was wet and heavy. Every shovelful felt like hauling a couple gallons of water from the walkway to the growing heaps along its edge. It got me thinking about the sun, which has an average density of 1.4 times that of water. I could just about imagine what it would be like lifting shovels of dense hydrogen gas from beneath the sun’s surface. Definitely hotter than snow.

You might wonder why, if the sun is made mostly of the lightest gas we know, that it could be so heavy. Density varies from the visible surface of the sun, where it’s like the rarefied air high in our atmosphere to the core, where it’s 150 times greater than water on Earth.

This cutaway shows the sun from core to surface (photosphere). The core temperature is around 30 million degrees. Hydrogen there is under so much pressure from the crushing force of gravity that it fuses with other hydrogen atoms to create helium, liberating powerful gamma radiation in the process. This energy eventually leaves the surface as light. Illustration: NASA/CXC/M.Weiss

It all comes down to pressure. The sun is 864,000 miles across and contains 99.86 percent of the the entire mass of the solar system. If the sun were hollow, you could fill it with 1,000,000 Earths. That’s a gigantinormous of matter, and matter matters when it comes to gravity. The sun holds itself together with gravity. Even if it’s in the form of light gases like hydrogen and helium, the intense gravity of so much material crushes the sun’s core to extremely high densities. The higher the density the greater the pressure. The extreme pressures in the core cause hydrogen atoms to meet and fuse into helium in a step-by-step process that releases energy in the form of gamma rays. Some 10,000 to 100,000 years later, the gamma rays reach the photosphere, the shiny disk of sun with which we’re familiar. During their long journey from core to surface, they lose a bit of energy every step of the way. Thousands of years later, when they finally leave the sun’s surface, they’ve been transformed into visible, infrared (heat) and UV light, all of which are far less energetic than gamma rays. Sunlight streams into space and arrives on Earth eight minutes later to light our days.

So the light that gives us blue skies and sunsets was likely created before the dawn of civilization in the Middle East. Fusion that liberates energy in the sun’s core this day after Christmas won’t see "the light of day" for at least another 10,000 years.

For now, I’ve finished shoveling the driveway, car and walkway but as I peer out the window, the roof awaits.

An artist’s view of the binary star Algol. The brighter companion is at left is Algol A. The larger orange star, Algol B, is the one that does the eclipsing. The stars are close enough that gas is pulled from from Algol B to Algol A by gravity.

Interesting astronomical events remaining in the year 2009 include a nice passage of the moon through the southern half of the Pleiades on Monday the 28th and a Blue Moon, or second full moon of the month, on New Year’s Eve. Tonight (Saturday) the curious star Algol in Perseus the Hero will undergo one of its periodic fadings for a couple hours centered on 8:24 p.m. Central time. Algol’s a very close double star. Every few days the larger, dimmer companion passes in front of and eclipses the brighter star. This causes Algol to fade from the second brightest star in the constellation to one of the dimmer ones. The change in brightness is very easy to see with your naked eye alone. If you go out early this evening — say around 6-6:30 p.m. — and use the chart from this blog, you’ll find Algol at normal brightness, about equal to nearby Mirfak. Algol will be in the northeastern sky below Cassiopeia.  Look again around 8:30-9 p.m. and its change in light should be obvious.

From Astro Bob to everyone out there – I hope you’re all enjoying the holiday and I wish you a feast of good things for the heart and mind in 2010! The ornament above is from our Christmas tree while the galaxy pair, called Arp 274, was taken by the Hubble Space Telescope

We opened gifts this morning as snow turned to rain outside the window. There’s already 20 inches of snow on the ground and good cheer all around. It’s great having our daughters home. Christmas and the snowstorm have made them happy captives for the time being. I received some fine gifts like chocolate-covered, glazed sunflower seeds (a delicacy!), books on bird watching and geology, a new sweater and my perennial favorite, jelly bellies. The beans must be eaten one at a time so each can be savored.

Now that the plow’s just gone by, it’s time to fire up the snow blower again and reconnect with the bigger world out there. Before I do, I just want to thank you, the readers and everyone who contributed photos and comments during the past year. You’ve helped to make this blog what it is — a place to share the natural beauty of the night sky. I appreciate it.

Relax, eat well and we’ll see you again tomorrow.

The Cassini spacecraft imaging team got into the holiday spirit and produced this charming video showing the dance of Saturn’s moons. The photos were compiled between August and November this year, knit together and set to the music of the Dance of the Sugar Plum Fairies from the Nutcracker Suite. For more details, click here.

Lit by the thick crescent moon two nights ago, clouds stream eastward during this time exposure. Orion is off to the right (the three Belt stars are vertical to the horizon). Details: 15mm lens at f/2.8, 30-second exposure at ISO 800. Photo: Bob King

Sometimes clouds at night are a good thing. I had fun two nights ago shooting time exposures of the sky with a wide angle lens while shards of clouds blew by. They added a bit of movement and excitement to the every steady patterns of the constellations. Today the clouds are dumping heavy snow all over the region in our first blizzard of the season. The sky won’t be clear by a long shot by this evening but rest assured the first quarter moon will still be shining serenly overhead just 10 miles away in the up direction. For those who might be more fortunate, the moon will make finding the Great Square of Pegasus an easy task. From the Square, you can step your way to the east into Andromeda, which is connected to Pegasus.

Clear by you? If so, go out tonight between 6 and 8 o’clock and use the quarter moon to direct you to the Great Square of Pegasus. It will lie a half-fist or about three fingers below the left hand side of the Square. Created with Stellarium.

Mars normally moves eastward (to the left as you face south) in our sky as it orbits the sun, but about every two years, near the time of one of its close approaches to Earth, the planet appears to stop and reverse direction. Mars stopped just short of Leo’s "Backwards Question Mark" this week and began tracking back toward Cancer the Crab. Illustration created with Stellarium.

Something else happened around the solstice this weekend. Just a quiet thing. Mars changed directions in the sky. For over a year it’s been traveling its usual eastward direction, bopping along from one zodiac constellation to the next, but on December 20, it stopped. Today it’s moving in the opposite direction or west. This switch from east to west confounded the ancient astronomers and led to the creation of all sorts of "wheels within wheels" schemes in an attempt to explain Mars’ backward or retrograde motion. (The Mars movie at left was created by Emil Kraaikamp with images he took over a period of 2 1/2 hours on December 15.)

The other week I got a question from a student in a community education class. Her friend, who follows astrology, was concerned that things might take a dark turn when Mars began moving in retrograde motion. I assured her that astronomically it happens all the time, and like so many things in astronomy, it’s all a matter of perspective. Since the Earth is closer to the sun than Mars, it moves faster — 18.6 miles per second versus Mars’ 14.9 miles. Like cars on a multiple-lane freeway, Earth catches up to Mars every two years and then passes it. As we do, Mars’ eastward motion appears to slow, stop and then reverse. Picture the freeway again.  The car is ahead of us, then appears to slow down as we pull up alongside it and finally moves "backwards" and drops behind us as we pass.

Since Earth moves in a nearly circular orbit rather than flying through space in a straight line like a car on a freeway, we’ll see Mars resume its normal eastward motion several months after we pass it by. Retrograde motion begins slowly but will pick up speed over the coming weeks. Its change in position in relation to the Sickle will be obvious by early next month.

It’s easy to find the bright orange planet in the eastern sky around 9-10 p.m. If you notice where Mars is now in relation to the Sickle-shaped head of Leo or its brightest star Regulus, you’ll be able to follow its westward drift with your own eyes. Next spring, Mars will appear to slow down again, turn around and head back toward Leo. To help you better picture what’s going when Mars changes direction, just follow the sightlines in the NASA diagram at right.

If you have an especially active imagination, you might even be able to picture our planet zooming by Mars in something resembling a planetary stock car race.

At the moment, we’re still catching up with the planet and getting closer night by night. That means Mars continues to wax brighter and bigger in the night sky. We’ll be at the D position (right) at the end of January and then continue along our merry way. Through a small telescope magnifying around 100-200x, Mars looks like a very small orangish disk with vague dark markings and one prominent feature — the north polar cap. The two Mars rovers have been exploring the planet’s surface for nearly six years now and have uncovered clear evidence of ancient water flows. The Spirit rover, while still operating, continues to resist controllers best attempts to get its wheels unstuck from the gritty Martian soil. With Martian winter coming, scientists are concerned it may not get the power it needs to survive because it can’t position itself to aim its solar panels sunward. Opportunity rover on the other hand is doing very well and currently preparing to grind into what appears to be a chunk of Martian bedrock controllers have named Marquette Island.

Finding Mars isn’t too hard. You can look low in the east-northeast around 10 o’clock and Mars is the brightest object you’ll see. It has a distinctive reddish hue. Or you can take the scenic route and start with Orion’s Belt which points you to Sirius. From Sirius, make your way to the left (north) to Procyon and from there to Mars in the northeastern sky. Created with Stellarium

Orion the Hunter rises over Lake Superior as participants in the winter solstice gathering in Two Harbors warm themselves by the fire. All photos: Bob King

I hope you celebrated the first day of winter yesterday with at least a nod to the sun. Maybe you attended a party like my friends and I did. We joined the winter solstice gathering in Two Harbors, a small port north of Duluth. Most of the attendees huddled around the bonfire or stopped to look through a telescope at the moon and Jupiter. A fire is such a good thing to return to on a cold night. My fingers froze up while trying to explain the hows and whys of the sun’s yearly motion through the zodiac. Five minutes by the fire and all was good again.

Several participants really got into the spirit last night and danced around the fire to the beat of the drums.

The drummers explore ear-pleasing rhythms during Monday night’s winter solstice celebration.

A group of musicians had brought drums. When I arrived, people were drumming in polyrhythms while others danced around the fire as Orion rose over the deeps of Lake Superior. At the goading of a friend, I even took up a drum myself. OK, I was a little self-conscious but I’ve always loved complicated rhythms and I’m an ace finger drummer on the dinner table. I want to thank Ellen Moore Anderson and friends for putting the event together. It was a delightful way to bring in the new season. Surrounded by friends, light and rhythm, winter seemed a little less chilling.

In this photo taken today by the Solar and Heliospheric Observatory (SOHO), three sunspot groups are visible. Last week’s big spot group (#1035) has rotated off to the right and is no longer visible. Credit: NASA/ESA

As long as we’re on the topics of sun and solstice, it’s a good time to revisit what our star’s been up. Last week saw a big upswing in solar activity with the appearance of the large sunspot group numbered 1035.  It was a most welcome sight during what’s been the lowest low in the sun’s activity in a hundred years.

Besides the spots we see in normal white light, old 1035 and a new group along the opposite side of the sun pop into view in this SOHO photo made in very short wavelength ultraviolet light earlier today. Could we be on our way out of the solar doldrums? Credit: NASA/ESA

On Sunday I pointed my little telescope, equipped with a safe solar filter, at the sun and found that two new sunspot groups had developed just as 1035 disappeared around the sun’s edge. We don’t normally thing about it but the sun rotates like the Earth and planets with a period of about a month. Sunspots slowly march from one side of the sun to the other and then disappear around the backside. If the spots are large and complex enough, they’ll survive a full rotation and we’ll see them again a second time around. Spot 1035 had its day in the sun (excuse the pun) for two weeks before going ’round the far side. The orbiting SOHO scope, equipped with special filters, can still see lots of hot gases hovering above the 1035 high in the sun’s atmosphere even though the spots have gone over to the sun’s backside. Nice having an extra eye on the lookout.