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August 2018 Skies

Aug 04 2018 09:48 PM | cookman in This Month

Highlights: Comet Journal, Martian Landers, Meteor Showers, Planet Plotting, August Moon Focus Constellations: Coma Berenices, Bootes, Corona Borealis, Hercules, Ophiuchus, Aquila, Lyra, Cygnus, Cepheus, Draco, Ursa Major, Ursa Minor, Cassiopeia, Andromeda, Pegasus

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Cosmic Challenge: Campbell's Hydrogen Star

Jul 31 2018 06:56 PM | PhilH in Phil Harrington's Cosmic Challenge

American astronomer William Wallace Campbell spotted this unusual star-like object through a visual spectroscope at Lick Observatory in 1893. He could tell immediately from its spectrum that, despite its stellar appearance, he was not seeing an ordinary star at all. Instead, he had spotted an uncharted planetary nebula.

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July 2018 Skies

Jul 02 2018 02:42 PM | cookman in This Month

Highlights: Comet Journal, Martian Landers, Meteor Showers, Planet Plotting, July Moon Focus Constellations: Leo, Coma Berenices, Bootes, Corona Borealis, Hercules, Ophiuchus, Aquila, Lyra, Cygnus, Cepheus, Draco, Ursa Major, Ursa Minor, Cassiopeia, Camelopardalis

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Cosmic Challenge: Dissecting M101

Jul 01 2018 05:22 AM | PhilH in Phil Harrington's Cosmic Challenge

Just spotting the gigantic Pinwheel Galaxy, M101, can sometimes be challenging enough. Its low surface brightness can drive suburban observers crazy, especially when we see photographs that show it so big and bright, or that it is listed as 8th magnitude. It all comes down to surface brightness, or more accurately, lack of surface brightness. Seeing the dim glow of the galaxy's small core, or the even dimmer glimmer of the surrounding spiral arms, can take a concerted effort. But with time and patience, M101 is visible, with difficulty, through 50-mm binoculars even given a suburban sky with a naked-eye limiting magnitude of perhaps 4.5.

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June 2018 Skies

Jun 08 2018 01:42 PM | cookman in This Month

Highlights: Comet Journal, Martian Landers, Meteor Showers, Summer Solstice, Planet Plotting, June Moon Focus Constellations: Leo, Lynx, Camelopardalis, Cassiopeia, Cepheus, Ursa Minor, Draco, Ursa Major, Coma Berenices, Bootes, Corona Borealis, Hercules, Lyra, Cygnus, Aquila

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Cosmic Challenge: Glimpsing Vesta

Jun 01 2018 06:34 AM | PhilH in Phil Harrington's Cosmic Challenge

Vesta turns out to be more like a mini-planet than like the chunks of rock most think of as asteroids. Dawn's measurements of the gravity field provided good evidence that Vesta's interior is separated into layers, much like Earth did as the planet was forming. Vesta's dense core - apparently once molten, but now solidified - is composed principally of iron and nickel, just like Earth's. Estimates place it at 125 to 150 miles (200 to 250 kilometers) across. Surrounding that is the mantle, which in turn is covered by the veneer of the crust, about 12 miles (20 kilometers) thick. It is now believed that early on Vesta was likely still accumulating material to become a full-fledged planet when Jupiter's immense gravity intervened, putting a stop to that. As a result, when we look at Vesta, many believe that we are seeing a protoplanet frozen in time.

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May 2018 Skies

May 05 2018 09:24 AM | cookman in This Month

Highlights: Comet Journal, Martian Landers, Planet Plotting, May Moon Focus Constellations: Leo, Çancer, Gemini, Auriga, Lynx, Camelopardalis, Cassiopeia, Cepheus, Ursa Minor, Draco, Ursa Major, Coma Berenices, Bootes, Corona Borealis, Hercules

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Cosmic Challenge: M109

May 01 2018 05:20 AM | PhilH in Phil Harrington's Cosmic Challenge

Messier did not live to see a second edition of his catalog, but objects 104 through 110 have been added posthumously by others. M109 joined the ranks in 1953, when astronomy historian Owen Gingerich noted Messier's observations of six additional "Méchain objects," now known as M104 through M109.

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April 2018 Skies

Apr 14 2018 08:00 AM | cookman in This Month

Highlights: Comet Journal, Martian Landers, Meteor Showers, Planet Plotting, April Moon, Easter, April Fool's Day, Friday the 13th Focus Constellations: Leo, Çancer, Gemini, Taurus, Auriga, Lynx, Camelopardalis, Cassiopeia, Cepheus, Ursa Minor, Draco, Ursa Major, Coma Berenices, Bootes

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Cosmic Challenge: Leo II

Mar 31 2018 09:54 AM | PhilH in Phil Harrington's Cosmic Challenge

Last April, this column profile the dwarf spheroidal galaxy Leo I, discovered by chance in 1950 by astronomers Robert Harrington (still no relation!) and A.G. Wilson as they were scanning the Palomar Sky Survey. I ended that column saying that "Using the right eyepiece and knowing the field will help you add this dwarf spheroidal to your list of conquered challenges with comparative ease. But don't get too cocky. Spotting its sibling, Leo II is an even greater challenge. But we will leave that for a future column." Well, that future is now.

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