My clear sky antennae are twitching so I’m optimistic for tonight. Given that a clear leap night is a rarity, we’d certainly want to look at something fitting for the occasion. I would offer the "Three Leaps of the Gazelle." This curious pattern, consisting of three pairs of stars, is an ancient Arab asterism that nowadays comprise the feet of the Great Bear or Ursa Major. Use the map above to track the stellar gazelle across the night sky. Start with the familiar Big Dipper, which stands on it Handle in the northeastern sky during the early evening hours.
While you’re out, keep an eye peeled for the Northern Lights. They snuck up on us two nights ago, hovering like a frosty breath below the "W" of Cassiopeia. Alaskan skies lit up last night with one of the best auroras of the year, all brought on by a strong solar wind. The wind is a stream of subatomic particles expelled by the sun. When they ram into our planet’s magnetic field at 450 miles per second, they tweak it in a way that sends cascades of high speed electrons and protons into our upper atmosphere. These strike air molecules and excite them to glow. Green and sometimes red are from oxygen. Reds are excited nitrogen. I’ll be out watching and I hope you will too.
(Orion’s Belt and the star Sirius — Bob King / News Tribune)
We’ve had numerous clear nights in the Northland over the week, some windy and some calm. Last night was a gem with air so still, it seemed frozen into place. Where I was, the temperature dropped to -12 F. Once my telescope cooled down, galaxies, comets and the planet Saturn came alive in the eyepiece.
I always like to take breaks from telescopic observing just to enjoy the spectacle of the entire sky. That’s when I noticed that the stars weren’t twinkling. Even Sirius (pictured above), which is notorious for its riot of flashing colors, was steady and serene. Our atmosphere is normally a turbulent sea, with air cells of different sizes and densities churning between us and our view of the heavens. This constant movement not only shifts the stars positions ever so slightly but causes them to brighten and dim rapidly. Our eyes see this as twinkling or scintillation.
The air cells also refract or bend a star’s light into individual colors, causing the brightest ones to flash every color of the rainbow. Sirius, being the brightest star in the entire sky, shows the very best twinkling colors. Binoculars will enhance the view even more. Sirius’ frenetic behavior on typical nights has put it high on the list of UFO impersonators.
(Two meteors during the 2001 Leonid meteor shower — Bob King/ News Tribune)
Susan of Virginia, Minn. wrote me the other day about something that really caught her attention. In her words: "I was on Highway 33 on Friday, Feb. 15th. I’m not sure what time it was, maybe 9 or 9:30 and to our east, a huge green ball/star/meteor/ufo fell from the sky into the woods. Another friend driving ahead of us saw it as well."
Susan, my first thought was aliens because of the green color but then logic grabbed hold. By the way, how did we humans decide on green as the preferred color of extraterrestrials? Do we secretly envy plants and their ability to use sunlight to make energy?
Of course what Susan saw was an especially bright meteor. It’s not uncommon for them to be green but sometimes you’ll also see red, orange or blue colored ones too. The colors arise from materials on the meteorite’s surface heated by friction as well as interactions with our atmosphere. Each time you see a "shooting star", you’re witnessing the burn up of a small fragment of ice or rock ejected long ago by an asteroid breakup or a comet. The Earth plows into these bits the way you plow into bugs on a summer’s night in your car. Most are no bigger than a sunflower seed, but when they strike the rarefied air overhead at 25,000 to 150,000 mph, they vaporize in a glorious flash.
Meteors often seem very close because we don’t have any good comparisons for distance. It may look like that big ball of fire landed in the field nearby but because meteors burn up 60 miles overhead, almost all of them are really very far away. Even if one is large enough to survive the fiery plunge, the atmosphere puts the brakes on so quickly that the meteorite is "dark" during the last 15 miles of its journey to the ground.
Bright meteors aren’t limited to meteor showers and can happen at any time of year. That’s why it’s always worth your while to look up.
(The sun sets over Duluth earlier this winter – Bob King/News Tribune)
Two glorious hours. That’s how much more sunshine lights our faces and accompanies us to and from work and school since the winter solstice. While walking the dog this morning, it struck me just how much further north the sun has traveled since December 22. From my vantage point, it now rises from behind the neighbor’s house instead of between the popples in their woods. Checking the Old Farmer’s Almanac, I see that the sun follows the same arc across the sky as it did last October 15. So why aren’t our temperatures in the 50s and 60s you ask? Not only does the snowcover come into play, but there’s a seasonal lag in temperatures. It takes our planet time to warm up to summer and then time to slowly cool down to winter.
The air temperature will catch up to the sun’s arc but before that happens, I’m going to keep my gloves close at hand.
Such a fine weekend with two clear nights and tiny hints of spring. Last night I heard the welcome monotone call of a saw-whet owl between the growl of snowmobiles. Saturday, the day named after the agricultural god Saturn, was a special day for that planet. It reached opposition Saturday night when it rose at sunset. Opposition simply means that the planet is opposite the sun in the sky and closest to Earth. Close in astronomy is a relative term of course. In this case, that would be 770 million miles.
You may have seen Saturn in Leo last week when the moon parked to the right of it during the eclipse. If not, it’s easy to find in the constellation of Leo the lion. Face northeast and find the Big Dipper around 8 p.m. Take the two stars at the top of the Dipper Bowl and shoot a line through them to the right. Keep going until you arrive at a pair of bright stars. The lower, brighter one is Saturn, and the upper one is Regulus, Leo’s brightest star. To find the outline of the entire constellation, just refer the photos below from the eclipse.
Saturn is the most distant of the easy naked eye planets and its cloudy atmosphere gives it a pale yellow tint. If you have a pair of 10x binoculars and can hold them very steady and focus sharply, you’ll see that the planet has an oblong shape caused by its rings. To truly appreciate their beauty however, you’ll need a small telescope. Nothing fancy mind you. Just something that magnifies at least 30x. The rings, which consist of chunks of ice and rock, are 150,000 miles across but only about 150 feet thick. Their tip varies as seen from Earth as Saturn orbits the sun. Every 15 years we see them edge-on, and in all but the very largest telescopes, they completely disappear. I’ve seen this weird aspect of the planet several times in my life and can tell you, that without its rings, Saturn is a stranger in the night sky. Watch for it to happen in 2009.
Do we really have to wait until December 2010 for the next lunar eclipse? It’s rare when so many people share the same moving event. It seems to bring us all a little closer. Like me, you may wish eclipses were more frequent. And they would be if the sun, Earth and full moon lined up exactly in a row each month. Unfortunately the moon’s orbit is slightly tilted, so the full moon nearly always passes just a little above or below the shadow cast by our planet and no eclipse occurs. Tonight the sky will be dark and moonless for almost an hour after twilight’s end. This is a perfect time to spot the planet Mars nearly due south and very high in the sky. Look for a reddish "star" high above the outline of the constellation Orion. Start with Orion’s famous three-starred belt and just keep going up until your neck almost hurts. Yeah, that’s Mars up there. Over the coming weeks, the Red Planet will slowly move eastward (to the left) through the stars of Gemini the Twins, one of the zodiac constellations. A keen-eyed observer should be able to detect its movement in a matter of days as it clips along at over 50,000 mph in its orbit around the sun.
(Lunar eclipse montage taken with a 300mm f/2.8 lens. Photo: Bob King, Duluth News Tribune)
(20 second time exposure of the eclipse scene. Photo: Bob King, Duluth News Tribune)
(30-second time exposure showing moon in starfield. Photo: Bob King, Duluth News Tribune)
I hope you had a chance to enjoy last night’s eclipse. The weather was perfect –OK, it could have been a little warmer — and the colors were spectacular. I especially enjoyed the sense of tranquillity during total eclipse. The bright stars joined the subdued moon in a quiet duet that lasted almost an hour. If you have photos or observations you’d like to share, please send them to my e-mail address and I’ll post them on this blog.
(Photo: An SM-3 missile is launched from a U.S. Navy ship. U.S. Navy handout image)
Here’s an update on the visibility of spy satellite USA-193. Rough weather in the Pacific Ocean looks likely to postpone the planned mission to shoot it down with an SM-3 missile. That means we’ll have another opportunity or two to see the ailing spacebird. Last night, it made a fine pass over the Twin Ports and was as bright as one of the stars of the Big Dipper. Here are times and directions for passes tonight and tomorrow night:
* Look southwest at 6:37 p.m. and watch for a moving point of light headed toward the northeast. USA-193 will be brightest and highest at 6:40 p.m. and then fade.
* Appearing in the west-southwest at 6:29 p.m., brightest at 6:31 p.m. in the northwest and disappearing at 6:33 p.m.
Weather prospects tonight are good for both satellite viewing and the total lunar eclipse. I’ll be out there and post a few photos tomorrow morning. Remember: applauding the eclipse will help keep you warm.
Last night my older daughter and I ran out of the house and into the cold for three brief minutes to watch the satellite USA-193 zip beneath Orion’s feet. It was a thrill to see it, knowing that this spy satellite’s days were numbered.
With a bit of luck, the U.S. navy will not have shot down USA-193 by the time you read this. This satellite, which was launched into orbit in December 2006, almost immediately malfunctioned. Since then its orbit has been gradually deteriorating to the point where it poses a hazard should it come down over a populated area. Many satellites break up and burn harmlessly in our atmosphere as their orbits gradually "decay." USA-193 however is large and contains hydrazine fuel which can be toxic. It also has technology that we wouldn’t want to end up in the wrong hands. That’s why the Navy plans to launch a missile to break it up into small pieces that will not survive re-entry. The latest information indicates this will happen Wednesday evening our time somewhere over the Pacific Ocean near Hawaii.
Here are the times to see it from the Duluth-Superior area tonight,Tuesday, February 19. USA-193 will appear as a fairly bright, speedy "star" moving upward from the southwest. To make sure you don’t miss it, be outside and ready a few minutes before the pass. Tonight might be the only chance we have unless the missile misses its target. (Photo: Launch of USA-193, public domain image)
* First appearance at 6:45 p.m. low in the southwestern sky and reaching maximum altitude at 6:47 p.m. high in the southeast. It will fade from view only one minute later as it moves into the northeastern sky.
If you observe it, please let me know and I’ll post your comments.
Thanks for stopping by to check out what’s going on in the sky this week. I will try to keep you up to date on celestial events you can see with your very own eyes, weather permitting of course.
I’ve looked skyward since age 11 and am constantly amazed at how many wonderful things go on over our heads all the time. If it’s clear Wednesday night — and the forecast looks good so far — we’ll get to see a total eclipse of the moon, an infrequent and very beautiful event. A lunar eclipse occurs when the sun, Earth and moon line up squarely in that order. When this happens, the moon slowly slips into Earth’s shadow and is darkened by degrees. Here are the times (Central Standard) Wednesday evening Feb. 20 to keep in mind for the eclipse:
* 7:43 p.m. — Start of partial eclipse
* 9:01 p.m. — Start of total eclipse
* 9:26 p.m. — Middle of total eclipse
* 9:51 p.m. — End of total eclipse
* 11:09 p.m. — End of partial eclipse
As you can see, a lunar eclipse is a leisurely event lasting over three hours. The moon starts out perfectly full and brilliant but is transformed to a deep, dark orange by totality. The color is caused by sunlight bent by Earth’s atmosphere that spills into the otherwise black shadow cone.
The weather is forecast to be very cold Wednesday night. If you want to pick just one time to go out, I’d suggest either the start or shortly before the finish of totality. The moon will be most colorful then. It will also be easy to see the planet Saturn, just to the left of the fully eclipsed moon, and the bright star Regulus, just above the moon. What an eyeful!
We’d love to hear of your eclipse impressions. Feel free to share your observations of the event on this blog.