... Bad Astronomy . ... Bitesize Astronomy . ... Last week's Snack talked about how black holes can affect the environment around them in such a way as to be very bright . ... It's a common misconception that black holes always have matter swirling into them. ... As this matter gets closer and closer to the black hole it piles up and a large, fairly flat disk forms. This is called the accretion disk , because matter from this disk accretes (that is, falls in) on the black hole. ... 2008 Phil Plait. ...

Astronomy Picture of the Day . ... Credit: Tunc Tezel Explanation: Why would Mars appear to move backwards? Most of the time, the apparent motion of Mars in Earth's sky is in one direction, slow but steady in front of the far distant stars. ... During the most recent such pass in August, Mars loomed particularly large and bright . Also during this time, Mars appeared to move backwards in the sky, a phenomenon called retrograde motion . ... Publications with keywords: Mars - retrograde motion . ...

... i.e., the interaction of light (generally from the sun or moon) with stuff in the air: molecules, water: ice and drops; crud; smoke.. ... Ice crystals: halos, sun pillars: the whiteness and brightness of snow . ... What to look for: common halos; coloured and white structures; symmetry and asymmetry . ... How crystals float in the air; the specific orientations mean that some halos change shape and position as the sun changes altitude . ... What do halos look like and how do we recognise them? ...

... Today this year's largest group of sunspots will cross the Sun's central meridian. ... The next day, the number of spots in the group reached five, and the day after, on June 2nd, it was possible to count thirteen sunspots on solar disk, which had been clear prior to this. ... This year's two most powerful active areas, which passed across the solar disk at the beginning of May, 2009, are set to appear in the Sun's eastern sector in two days, on June 6th. ...

... February 4, 1998 . A Passing Spaceship Views Earth . Credit: NEAR Spacecraft Team , JHUAPL , NASA . Explanation: This is how Earth appeared to the passing spacecraft NEAR. The Near Earth Asteroid Rendezvous (NEAR) spacecraft was launched from Florida, USA, planet Earth in 1996. After a quick flyby of asteroid Mathilde in June last year, NEAR passed the Earth two weeks ago on its way to asteroid 433 Eros. ... About APOD > . ... NASA Technical Rep.: ...

... Thin Line. I thought the time had passed when I could find beauty in the words I set the stage and the scenery, rehearsing every word Ch: But when I try to make it more, well, it was always less It's a thin line between pleasing yourself and pleasing somebody else So with my confidence on fire, I set to fixing up my role Separation of desires, it led me deeper down in the hole Ch (x2) Now I'm trying to get back to what I know that I should be Hoping to God that I was just a temporary absentee. ...

... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... The Perseid meteor shower, which this year peaked around midnight on the evening of August 12th, will continue at a low rate until around August 24th. ... Video clips in AVI and mp4 formats of some of the brightest Perseid meteors detected by the ObservatoryтАЩs cameras together with an image illustrating the parallel tracks in space of the Perseid meteors detected at Armagh can be found here . ...

... Tonight's Sky . ... Observing . ... Sky this Month . ... Astronomy for Kids . ... Can you explain Mercury's retrograde motion? Do other planets appear to do this also? ... When astronomers talk about retrograde motion, generally they refer to the apparent motion outer planets make as Earth passes them while orbiting the Sun. ... Get instant access to subscriber content on Astronomy.com! ... Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter. ...

... STScI-PRC00-34 A BIRD'S EYE VIEW OF A GALAXY COLLISION What appears as a bird's head, leaning over to snatch up a tasty meal, is a striking example of a galaxy collision in NGC 6745. ... However, the situation is quite different for the interstellar media in the above two galaxies - material consisting largely of clouds of atomic and molecular gases and of tiny particles of matter and dust, strongly coupled to the gas. ... The hot blue stars in this image are evidence of this star formation. ...

... Whenever Flint finds a call to a subroutine, or the source of a subroutine, it attempts to determine whether a subroutine argument is either input or output (this is called an arguments intent). ... Note that Flint expects an argument's intent to be either input or output or input/output. ... Usually Flint determines argument intents by other means than just allowing information to bubble up from the lowest level to the higher level routines. ...

... The awsome spectacle of a brilliant comet, with its long ghostly tail streaming behind it, is a rare event. ... Only one other comet, Comet Halley, was seen so far from the Sun, giving scientists an opportunity to watch it as it slowly warmed up and sprouted a tail. ... Comets are the Rip Van Winkles of the solar system -- mini-worlds that have changed little during their 4.5-billion-year nap far from the Sun. ... Observing Comets . ... Once, comets inhabited the entire solar system. ...