Astro Bob

  This Halloween we get a visit from both the Great Pumpkin and the Blue Moon. Halloween Blue Moons occur 3-4 times on average per century. Illustration: Bob King Let the Halloween mischief begin. As the little ones fill their trick or treat bags, a bright full moon will light the way. All full moons are special, but this one is unique for a couple reasons. It's the second full moon in the month which makes it a Blue Moon. And it happens on Halloween. Enjoy it because the next one won't light up your pumpkin until 2039.  There are three types of Blue Moons — the monthly Blue Moon, the seasonal Blue Moon and a moon that actually looks blue. The time between successive full moons is approximately 29.5 days, so we normally get one full moon per month or 12 per year. To squeeze a second full moon (Blue Moon) in there, the first full moon has to occur at the start of the month to make room for a second full moon (Blue Moon) 29.5 days later at month's end.  October's fi...

The sunspot group AR2778 is the largest of the new solar cycle. This photo was taken by NASA's Solar Dynamics Observatory (SDO) late Wednesday morning, Oct. 28.  NASA / SDO The largest sunspot group of new Solar Cycle 25 is getting out attention this week. If you have a small telescope equipped with a safe solar filter, take a look. Although the individual sunspots are only modest-sized, the group as a whole extends across 62,000 miles (100,000 km). Its official name is Active Region (AR) 2778.  The sun isn't a rigid body like the Earth but spins at rates that vary with latitude.  NASA Because the sun turns on its axis from east to west about once every 27 days, the sunspot group moves further to the west each day. It's currently in the southwestern part of the disk, so we have a few more days of observation before it rotates around to the backside. Notice I used the word "about" when describing the sun's rotation period. Unlike the rigid Earth, our star is a ...

  The Apennine Mountains will stand out boldly tonight (Oct. 24) on the 8-day-old moon. All you need to see them is a pair of binoculars and a partly cloudy sky. The mountain range defines the southeastern "shore" of Mare Imbrium, the Sea of Showers. You may also notice the 68-mile-wide crater Plato on the sea's northern shore. Bob King   I'm not a technical mountain climber. I don't use rope, only hands, legs and occasionally my rear end to clamber up and down the rocks. I don't mind expending the extra energy to hike to a hilltop because the wide-open view makes me feel happy inside and reminds me that I'm just a particle in the great stream of being.  A small telescope will show the Apennines, two additional mountain ranges and several prominent craters in the region tonight (Oct. 24). Mt. Hadley, located at the northeastern end of the chain, is the moon's highest peak.  Bob King With a small telescope and a little imagination, you can experience si...

Gosh, what a busy week, and it's only Wednesday. Congratulations to the NASA team for a flawless sample capture yesterday at Bennu. The OSIRIS-REx space probe successfully touched the surface of the asteroid, disturbed its ancient soil and rocks with a blast of nitrogen gas and snatched bits and pieces to return to Earth in 2023.You can take a tour of the asteroid and get to know its boulders by name in the video above. The agency will release new images  of the sample acquisition at a news conference today beginning at 4 p.m. CDT (5 p.m. EDT).  The author watches the aurora on a chilly evening several years back. The arc — visible in this photo — is the aurora's most common form. As activity increases, faint, parallel rays will often appear within the arc. Bob King Tonight (Oct. 21) and tomorrow night we have a shot a seeing the northern lights. As the sun is now near the minimum of its 11-year cycle, coronal holes rather than solar flares are primarily responsible for sendi...

This false-color, composite shows the Orionid meteor shower over Huntsville, Alabama in Oct. 2009. They peak again on the morning of Oct. 21.  NASA The Orionid meteor shower may be no match for the August Perseids, but it's special for different reasons: the material responsible for the annual shower comes directly from Halley's Comet, and the meteors it produces zing across the sky in the blink of an eye. Every October the Earth crosses the trail of dust and pebbles called meteoroids lost by the Comet during its repeated trips to the inner solar system. Heated by the sun, some of Halley's dirty ice (the principal ingredient of comets) boils away and releases the trapped debris. That material settles and spreads across the comet's orbit in a great band that travels like a conveyor belt around the sun. Twice each year, first in May and then October, Earth's orbital path intersects that of Halley's Comet. Our first encounter produces the Eta Aquarid meteor showe...

Uranus is the third largest planet after Jupiter and Saturn. Its atmosphere is mostly hydrogen and helium, but a small amount of methane present tints the globe a pretty shade of aqua.  NASA images We used Mars last week to point to the pulsating, red giant Mira in the constellation Cetus. Today we'll use it again, this time to direct us to Uranus. At Uranus we find ourselves in the cold, abysmal realm of the outer solar system far from Saturn's familiar rings and Jupiter's belted globe. The seventh planet lies more than 1.7 billion miles (2.8 billion km) from the cozy Earth this month.  Although nearly four times as large as our planet, Uranus's great distance makes it too faint for most of us to see without optical aid. But if you're going to spot it, now's the time to look — Uranus comes closest to the Earth at opposition which occurs on Halloween this year. This diagram shows the apparent size of the sun in fractions of a degree as seen from the eight plane...

  In this photo the zodiacal light is the tall, diffuse shaft of light that angles up from beneath the constellation Leo. Bright Venus glares near its base, and the Beehive star cluster appears father up its narrow end. I made the picture on Oct. 16 two hours before sunrise (5:30 a.m.) from Duluth, Minn. facing east over Lake Superior.  Bob King If you have access to a dark eastern sky I encourage you to get up about 2 hours before sunrise to see the zodiacal light sometime in the next two weeks. This enormous cone of glowing comet and asteroid dust resembles the soft, smoky look of the Milky Way but without its granulated, starry texture. Every clear morning it points upward from the eastern horizon like a subtle searchlight beam 2 to 2 1/2 hours before sunrise. Now through Oct. 29 is the best time to see it because no moon will spoil the darkness. The zodiacal light is widest and brightest near the horizon and tapers to a narrow cone as you look farther up. Be aware that it...