Community ed astronomy group observing Saturn in twilight last night – Bob King

Clouds dogged us for a while last night but our group of hardy astronomers perservered and saw Mars, Saturn and Mercury. Yes, Mercury. It’s back in the evening sky, tangled up in the orange glow of dusk. To find it, you’ll need a very open horizon to the northwest.

Find Mercury low in the northwestern sky during twilight — created with Stellarium

Look for a solitary bright star hovering in the sunset glow between 9-9:30 p.m. over the next two weeks. A pair of binoculars can be a real help in spotting this elusive planet against the glow of twilight. Once you see it in binoculars, finding it with your naked eye is easy.

Mercury, the smallest of the planets, never strays far from the sun from our perspective on Earth, which makes it one of the trickier planets to see despite its brightness. Its small orbit and distance from us combine to keep it forever buried in twilight. Right now Mercury gets the nickname of Evening Star. When it rises before the sun, it’s the Morning Star. 

Like the moon, Mercury goes through phases. At the moment, it looks like a tiny, nearly full moon through a telescope. Over the coming weeks, it’ll become a quarter moon and a crescent. Then the planet will drop down too close to sun to see, until it swings round the other side to become the Morning Star.

Catch it if you can. Next week the crescent moon will join Mercury for a beautiful pairing.

The clouds departed last night and left a spectacular sky in their wake. Saturn and Regulus were just two pinky fingers apart, and a real eye-grabber high in the southern sky. The great hunter Orion, and his retinue of winter pals, had toddled off to the west, while a whole new slew of stars pushed up from the east like so many shoots from the forest floor. Wood frogs, peepers and chorus frogs sang despite the cold. I like the company of amphibians when I’m out galaxy hopping with the telescope.

Planets Saturn (left) and Uranus show off their rings. –  NASA/HST

Any idea how many planets in our solar system have rings? If you answered four, pat yourself on the back. Up until 1977, only Saturn was known to possess them, but by 1983, three more planets — Jupiter, Uranus and Neptune — were added to the list.

Saturn’s rings, which are composed mostly of ice crystals and ice chunks in the range from snow to many feet across, have been known since the early days of the telescope. 

Uranus’ rings were discovered in 1977 when it passed in front of a star, an event called a stellar occultaion. Astronomers watched as the star dimmed briefly five times both before and after it was covered by the planet. Only a series of symmetrical rings would give this result. Nine years later, the Voyager 2 spacecraft beautifully confirmed the discovery by snapping photos of Uranus’ 13 very thin rings. The rings are dark and thin, and composed of an unknown material.

Jupiter (left) and Neptune. A bar blocks Neptune to prevent overexposure - NASA

Jupiter has several very thin dusty rings, discovered by in 1979 by the Voyager 1 spacecraft. Scientists believe the dust was released into orbit around the planet by meteroid impacts on small, nearby moons. Neptune’s four dark, dusty rings were discovered in 1983 the same way as Uranus, by stellar occultation. Once again, we got a much better look at them when Voyager 2 cruised by Neptune in the summer of 1989.

Most rings, including Saturn’s, are debris from impacts, or the remains of a moon that was shattered by an impacting asteroid or comet. The material cannot gather itself back into another moon because it’s too close to the powerful gravity of its mother planet.

Astronomers have discovered over 200 new planets orbiting other stars in our galaxy. As larger telescopes are built, and the first extrasolar planets photographed, I’m going to guess that our count of ringed planets will have nowhere to go but up.

Facing east around 9:30-10 p.m. this week – created with Stellarium

I bet you didn’t know there was a crown over your head these spring evenings. Corona Borealis, the Northern Crown, is easy to find if you can locate the Big Dipper. The constellation represents the crown worn by Princess Ariadne of Crete when she married the god Dionysus.

Face east, and follow the curve of the Dipper’s Handle down to pink-flashing Arcturus, a bright star hard to miss. Now stretch your arm out to the sky, and find the star that’s one fist to the left of Arcturus. Got it? OK, your next move is to drop down an equal distance to your left to Gemma (GEM-uh), the crown’s brightest star. 

If you look above and below Gemma, you should be able to discern a dim but distinctive semi-circle of six additional stars that comprise Corona Borealis. The figure reminds me of a horseshoe.

While it’s no Miss America bling, it only requires a little bit of imagination to see the famous tiara as the ancient Greeks did.

More of those bright Iridium satellites will be flaring in the night skies this coming week. Check the table below for times for our area. The times are precise and given in hours, minutes and seconds. Watch for a slowly moving "star" to grow steadily brighter, reach a peak of intensity and then fade away — all within about 30 seconds.

There’s also a possibility for northern lights late Monday night and Tuesday. The SOHO spacecraft recorded a large ejection of material from the sun in the wake a solar flare yesterday. This may reach Earth and trigger auroras in high latitudes, possibly for our region. In the short movie below, the position of the sun is outlined by the white circle. A metal disk covers the sun to prevent glare during the picture taking. 

Large ejection of material from the sun recorded by SOHO yesterday – NASA/ESA

Iridium satellite info:

The fun still continues this afternoon and evening at the planetarium on the UMD campus. Astronomy Day goes on despite the spring snowfall. Don’t miss tonight’s guest speaker, Dr. Lawrence Rudnick, at 6:30 p.m. when he presents his program on "The Greatest Impact: We are Stardust."

Look southeast tomorrow morning to find the moon and Jupiter – created with Stellarium

My Clear Sky Chart for the Duluth area shows clearing around dawn tomorrow morning, the 27th. For the hardy, I’ve prepared a chart for finding the planet Jupiter by using the waning moon. Look in the southeastern sky around 5 a.m. and you can’t miss Jupiter. It’s that bright "star" perched directly above the moon. If you have a pair of binoculars and a steady hand, try finding Jupiter’s brightest and largest moon, Ganymede (GAN-ee-mead). Focus carefully on the planet and look very close just to the right of Jupiter’s disk. You should see a little "star" there. That’s Ganymede.  

Ganymede (at left) is 3,280 miles across and larger than both Mercury, a real planet, and Pluto, now reclassified as a dwarf planet. Since it orbits Jupiter, Ganymede is considered a moon, but if it were in a separate orbit around the sun, it would certainly be considered a planet.

While you’re gazing skyward, see if you can pick out the figure of the "Teapot" of Sagittarius. It’s one the best known asterisms in the night sky. And if you’re just too weary to get up early on a Sunday, no problem. In June, Sagittarius and its planetary companion Jupiter will rise during regular evening hours.

Tomorrow is Astronomy Day, an annual celebration of all things celestial. The weather looks horrible, which is all the more reason to come down to the Marshall Alworth planetarium on the UMD campus for a fun day of talks, sky shows, telescope and meteorite displays, and even a simulated mission to a killer asteroid.

Simulated Mars mission (left) and telescope displays on Astro Day ’07 – photos by Eric Norland

The event is put on by the planetarium staff, the UMD Astronomy Club and the Arrowhead Astronomical Society. Doors open at 10 a.m. Saturday, April 26, and all shows are free and suitable for all ages. To see a complete schedule of events, just click on the link above.

To top off the day, Dr. Lawrence Rudnick, distinguished teaching professor of astronomy at the U of M, will give the keynote address in Life Science, Room 185 at 6:30 p.m. His lecture is titled "The Greatest Impact: We Are Stardust."

See you there!

Monument to Laika, the first dog in space. It’s located in Moscow – AP

Earlier this month, Russian officials unveiled a monument to Laika, one of the world’s most famous dogs. Laika, whose name means "barker", was a two-year-old stray, who was launched into space aboard the Sputnik II spacecraft on November 3, 1957. This was only the second spacecraft ever launched, and Laika was the first living being to go into orbit.

Sadly, things did not go well for the lively dog. She survived the launch and even ate her food but her pressurized cabin overheated. Between that and the stress of flight, she died only hours into orbit.

"Laika was quiet and charming," Dr. Vladimir Yazdovsky wrote in his book chronicling the story of Soviet space medicine. He recalled that before heading to the launch pad, he took the dog home to play with his children. "I wanted to do something nice for her: She had so little time left to live," Yazdovsky said.

Laika remains a pioneer. She and several other dogs were flown into space to test the effects of launch and the space environment on animals. Her sacrifice led to the first human flight on April 12, 1961 by Soviet cosmonaut Yuri Gagarin. 

And the rest is history.  

(Photo at right shows Laika in her padded cabin in November 1957 – AP) 

Moon at perigee (left) and apogee  — NASA

The nights are finally getting their voices back. I heard the wood frogs clucking for the first time yesterday evening while out observing with an astronomy group. We toured the galaxies, a few clusters and Saturn, the gem of the spring sky. Meanwhile the frogs sang music to the beat of their tiny, passionate hearts.

Now that the moon is past full, it rises quite late. Tonight you won’t see its jolly face until just after midnight. The moon’s orbit around the Earth is slightly elliptical or oval, rather than a perfect circle. This causes the moon’s distance from us to vary from about 214,000 miles to 244,000 miles during the course of every month.

Today the moon is furthest from Earth for the month of April, a situation called lunar apogee. Back on April 7, the moon was at perigee, or closest distance. If you look at the photo above, you’ll see there’s a significant size difference between these extremes. There’s also a difference in brightness.

Can you see this with your eye? It’s very difficult. Without a second moon nearby for comparison, it’s hard to recall if the moon tonight was smaller than what you remembered two weeks ago. But it does show up nicely when recorded with a camera.

Today is warm and sunny and gorgeous, reason enough to celebrate. But if you need an additional excuse to party, consider the (un)momentous occasion of lunar apogee.

Look high in the south around 9:30-10 p.m. to find the Beehive – created with Stellarium

Tonight’s forecast is for clear weather so why not step outside and see if you can spot the famous Beehive Cluster in the constellation of Cancer the Crab. I’ve always enjoyed this spooky looking little cloud. To find it, look high in the south at nightfall. Use Saturn and Mars (see map above) to point you to the cluster, located about mid-way between the two. It sits squarely in the "empty region" between Gemini and Leo.

If you live where the sky is dark, you should see a hazy puff about the size of the moon. To make it easier to see, practice the technique known as averted vision. Look to the side and around the spot instead of staring directly at it. City observers will need low power binoculars to pull the cluster out of the skyglow.

Time exposure photo of the Beehive star cluster – Bob King / News Tribune

The Beehive is a cluster of several hundred suns 577 light years away. It’s similar to the Pleiades (Seven Sisters) cluster except further and fainter. Your eyes sees an unresolved glowing patch but binoculars will reveal dozens of stars, some in pretty chains.

Galileo was the first to resolve the Beehive in his small telescope and he counted 40 stars. It’s other name is Praesepe (Pree-SEE-pee), which means manger in Latin. The ancient Greeks and Romans saw this misty glow as a manger with two donkeys eating from it, represented by two nearby stars.

Whether you see a manger or a buzzing hive of bee-stars, this pretty binocular cluster is worth a look on the next clear night.

The nearly full moon was a juicy cantelope last night as it rolled up from the horizon richly orange and alone in a big sky. I was surprised by the sight, and stopped right there in my walk for a few minutes of face to face. The wind blew like crazy but the moon kept its cool, mounting above the ponds and trees with its familiar, steady rhythm.

Leonid meteor streaking through Leo in 2001 — Bob King

Tomorrow morning before dawn the Lyrid meteor shower will be at its peak. Although the first notable shower of the year, the Lyrids (LYE-rids) are not for the faint of heart. They normally produce about 15-20 meteors per hour, but there are two challenges to would-be Lyrid watchers: you have to get out there from 3-4 in the morning, and second, the light from the nearly full moon will brighten up the sky, making it hard to see the fainter ones.

If you’re up for the challenge, then set your alarm, relax outside in a reclining chair under a blanket or sleeping bag, and look directly overhead. The meteors will appear to radiate from near the bright star Vega in the constellation of Lyra (LYE-ruh), hence the shower name.

Comet Hyakutake 1996. Will dust from its tail produce a meteor shower too someday? – Bob King

The Lyrid meteors are tiny "crumbs" boiled off Comet Thatcher by the sun during the comet’s many passes through the inner solar system. Every year in mid-April, the Earth travels through this dusty cloud of debris, and the tiny pieces strike our atmosphere, burning up as meteors.

The most famous meteor shower of the year are the familiar Perseids in August. They trace their origin to Comet Swift-Tuttle. The good news is that the moon will not be as much of a factor then as with tomorrow morning’s Lyrids.

So, are you up for the challenge?