Astro Bob blog: Halley's Comet returns in a zillion piecesA hot new sunspot plus tips on watching Friday morning's meteor shower
By: Bob King, Duluth News Tribune
Halley's Comet returns in a zillion pieces
My sun viewing setup this morning: a small refracting telescope on a tripod with a solar filter over the tube end. The filter is optical-quality glass coated with aluminum. The shiny coating reflects and absorbs all but a tiny percentage of the sun's light allowing for safe viewing on the eyepiece end. Photo: Bob King
I set up my little scope with a solar filter and peered at the sun this morning before a wave of stratus clouds overtook the perfect blue sky. Overnight a brand new sunspot region had emerged dubbed number 1069. Although small, it looked busy. Simple sunspot groups have what's called a "beta" configuration meaning one part of the group acts like the north pole of a magnet while the other end acts as the south pole. Beta groups are often called bipolar and have a main leader spot and a smaller "follower" spot. The two poles are cleanly separated and the probability of big solar flares developing is low. Remember that flares are one of the ways particles from the sun reach the Earth to produce auroras.
The sun as photographed earlier today by the Solar and Heliospheric Observatory (SOHO). The spot group to the left and below 1069 is a simple bipolar group. 1069 has a more complicated beta-gamma configuration. Credit: NASA/ESA
Region 1069 is more complicated. It has a "beta-gamma" magnetic field meaning that while the group still has leading and following spots, it has more than one set of polarities (north and south poles) mixed together instead of cleanly separated. Groups like these are very active magnetically and often the site of sizeable solar flares. I'll be watching this one and report back if it produces any storms that might trigger northern lights back here on Earth.
If you have a telescope and have never used it to observe the sun, don't do so unless you have a proper solar filter. With the right filter, sun viewing is very enjoyable for several reasons:
* It's warmer than night sky watching
* The sun is big and there's lots to see including sunspots and their fascinating textures, bright patches called faculae which form at the birthplaces of sunspots and often remain after they disappear, the granulated texture of the sun and the march of spot groups across the sun's face as it rotates.
* Can't beat the viewing hours -- always during daylight.
Look about halfway up in the east or south Friday morning between about 2:30 and 4 a.m. to see the annual Eta Aquarid meteor shower. The radiant (red circle) is in the northern half of the constellation Aquarius. Created with Stellarium
Just a heads up. We've got a modest meteor shower called the Eta Aquarids (AY-tuh uh-QUAR-ids) that will peak this Friday morning in the hour or two before dawn. Viewing conditions aren't the best for northern hemisphere sky watchers because the radiant point -- the place in the sky from which the meteors will appear to originate -- is low in the southeast just before dawn. The last quarter moon will also be in the vicinity, and its glare will drown out the fainter shooting stars. The further south you live, the higher the radiant will be which is why southern hemisphere viewers are favored for this shower.
At best, the Eta Aquarids produce about 30 fast-moving meteors per hour, but northerners are more likely to bag closer to 10 per hour. If you're out around 3 a.m. when the radiant rises, you might be lucky enough to spot an Eta Aquarid "Earth grazer". These are meteors that skim or graze the atmosphere and take what seems like forever to cross the sky. I've seen just one Earth grazer -- a member of the Leonid shower in November -- and it was spectacular. The meteor slowly rose up in the east and took many seconds to cross nearly the entire sky.
Halley's Comet in 1986 during its most recent appearance. It'll return again in the summer of 2061. Credit: NASA
Friday's shower is interesting for yet another reason -- the meteors you'll see originated in Halley's Comet. Bits and pieces of the comet were left behind hundreds of years ago during one of Halley's trips through the inner solar system. Each year in early May our planet passes through this stream of debris and we see a meteor shower. Wishing you clear skies!