Astro Bob blog: A feast of choice Milky Way morselsSolar flare news plus three challenges for the sky-minded
By: Bob King, Duluth News Tribune
A feast of choice Milky Way morsels
In this photo taken this morning by the Solar Dynamics Observatory, sunspot 1093 looks peaceful enough, but may provide more excitement in the form of additional flares in the coming days. Credit: NASA/SDO/HMI
Yesterday morning a sizeable flare blew up in sunspot group 1093. Subatomic particles from the explosion may deliver a glancing blow to Earth's magnetic bubble and stimulate aurora on August 9 and 10. If this happens, it will most likely occur in far northern latitudes, but I wanted to bring it to your attention in case there's spillover for sky watchers in the northern U.S. Keep your eyes peeled for auroral shards as you watch for Perseid meteors in the nights ahead.
This map shows the sky from now through mid-August around 10:30-11 p.m. when Sagittarius is due south and highest in the sky. You can use Deneb and Altair in the Summer Triangle to point you in the constellation's direction. Maps created with Stellarium
The portion of the Milky Way that passes through the constellation Sagittarius the Archer, better known as the Teapot, sports an abundance of celestial jewelry for your eyes these August evenings. Ready for a little hunting? Join me in the coming nights to take advantage of the riches of the southern realm.
Challenge #1: Find the Teapot. Sagittarius is low in the southern sky from my latitude. Only in the southern U.S. and further south does it reach a more commanding altitude. One saving grace -- the figure or outline of the teapot is easy to see. Make sure you're somewhere away from urban light pollution and have a clear view to the south before starting your hunt. Use the bright stars of the Summer Triangle to help you on your way.
In this closer view, we hone in on a half dozen star clusters and nebulas visible in most binoculars from reasonably dark skies. While there are more clusters in the area, I've chosen the brightest, which happen to form a little hexagon above the top of the teapot. The circle at upper right is the piece of sky covered by a typical pair of binoculars. The "Stinger" is a moderately bright star that forms the tail-end of Scorpius.
Challenge #2: If you can see at least a faint hint of the misty band of the Milky Way across the top of the Sagittarius, you're ready to go deeper. Take your binoculars and point them at the star at the top of the teapot. Within the same field of view to the left is M22, the first globular cluster discovered and one of the brightest. An intriguing fuzzy glow with a brighter center marks the spot. Globulars, as they're called, are light-years-wide starry spheres. M22 in particular is nearly 100 light years across, 10,400 light years away and contains at least 70,000 stars. Clockwise from M22, we arrive at the open cluster M25. Depending on your binoculars' magnification and aperture, you'll be able to see a number of small stars gathered together like a compact patch of stellar daisies. Next is M17, also called the Swan or Omega Nebula because of its shape. At low power, it's another one of those fuzzy spots, but remember this as you view it -- you're looking at a star factory. Within that wisp of gas, hundreds of new stars are forming like the cherry tomatoes on the vine.
M23 is another open cluster that should reveal a few starry sparkles, while M8, nicknamed the Lagoon, is a large and bright nebula. You can't miss this one -- it's even visible with the naked eye. Look closely and you'll notice the Lagoon is extended in an east-to-west direction. There's also a star cluster buried inside the nebulosity. Can you pick out any cluster members? We wrap up with M28, the faintest deep sky object of the six. Like its neighbor M22, it's also a globular cluster but smaller and almost twice as far away.
Challenge #3: Ah, you thought we were done? Not quite. If you like extremes, try finding the southern version of the Northern Crown (Corona Borealis). Called Corona Australis (koh-ROH-nuh ahs-TRAY-liss),this dimmer crown is tucked below the bottom of Sagittarius. From a dark sky, I see a few faint twinkles, but once I aim binoculars its way, the arc of the crown is obvious. Obscure even for the ancient Greeks, this constellation, which represents the archer's crown, was one of the original 48 handed down to us from that era.
Here are a few photos of our featured deep sky objects to whet your imagination as you view them the next clear night:
The globular cluster M22 begins to resolve into individual stars in 3-inch telescopes and up. Credit: Jim Misti
M17 is a hotbed of star formation within our galaxy. The swan's "head" curves around the very black, square-like feature along the nebula's left side. Credit: Jim Misti
M23 is about 2150 light years from Earth and contains some 150 stars. Unlike the more compact, densely-starry globular clusters, open clusters, as their name implies, are more spread out. Many are easily resolved into stars in smaller telescopes. Credit: N. A. Sharp, REU Program, AURA, NSF, NOAO
The Lagoon Nebula (M8) already has a cluster of young stars cooking away while new ones are forming within the pink nebulous clouds. Credit: Jim Misti
Compare M28 to the photo of M22 above. They're both globulars but M28 is more distant. "M" numbers refer to the famous catalog of deep sky objects cataloged by 18th century French astronomer and comet hunter extraordinaire Charles Messier. Credit: Jim Misti