Circling a Black Hole at its Photon Sphere . ... One particularly interesting place near a black hole is its photon sphere, where photons can orbit in circles, a sphere 50 percent further out than the event horizon. Were you to look out from the photon sphere of a black hole , half of the sky would appear completely black, half of the sky would appear unusually bright, and the back of your head would appear across the middle. ... Disclosure: Video creator Robert Nemiroff is an editor for APOD.) ...

... 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. ...

... 2005 August 8 . Mars to Appear Normal This August . ... Regardless of numerous urban legends circulating, Mars will appear relatively normal in August. October is the best month to see Mars this year. ... As Earth catches up to Mars in their respective orbits around the Sun, Mars will keep rising earlier in the night. On 2005 October 30, Earth will have caught up to Mars and the planets will be the nearest to each other in their orbits -- this time around. ... About APOD | ...

... The blue bubble is a planetary nebula known as Abell 33. Planetary nebulae are created when an aging star blows away its outer layers of gas in a gigantic cosmic bubble. ... Creating the illusion of the cosmic diamond is a bright star along the rim of the nebula. ... The star is about 700 light years away, that is halfway between Earth and the nebula. ... At the centre of the ring, you can see the remains of the star that created this planetary nebula, now a white dwarf . ...

This month's Geminid meteor shower is expected to peak around the late evening of Tuesday 13th/early hours of Wednesday 14th. The shower is usually one of the best of the annual meteor showers, with many relatively bright, slow- to medium-speed fireballs. ... These meteors are believed to originate from the near-Earth asteroid, Phaethon, discovered by a NASA satellite in 1983. ... FOR FURTHER INFORMATION CONTACT: John McFarland at the Armagh Observatory, College Hill, Armagh, BT61 9DG. ...

... The TRACE images may be used without restrictions in publications of any kind. ... These two images, taken on 18 November 2000 at 15:54UT and 16:11UT, respectively, show such an event: the red circle in the image to the left shows a region where many loops are cooling, with bright loop tops (the intensity scales with the square root of the image to reduce the dynamic range). ... See also a collection of images related to the Sun, other cool stars, and solar-terrestrial effects . ... Images | ...

... Night Sky Questions . Q. I saw a bright light streak across the sky last night. ... A. Meteors are the bright trails left by fragments of natural space debris called meteoroids (usually chunks of rock or metal) falling through the EarthтАЩs atmosphere. ... As the Earth moves around the Sun over a year, planets will move in and out of view, so the sky changes.To confirm if it was one of the planets, go to www.heavens-above.com . ... Q. I saw a bright light moving steadily across the sky last night. ...

In this image by NASA's Hubble Space Telescope, an unusual, ghostly green blob of gas appears to float near a normal-looking spiral galaxy. The bizarre object, dubbed Hanny's Voorwerp (Hanny's Object in Dutch), is the only visible part of a 300,000-light-year-long streamer of gas stretching around the galaxy, called IC 2497. ... This Hubble view uncovers a pocket of star clusters, the yellowish-orange area at the tip of Hanny's Voorwerp. ... NASA/ESA/W. Keel (Univ. of Alabama)/the Galaxy Zoo Team ...

... 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. ...

... In principle, two observers on the ground can tell, by comparing the position of the same auroral arc against the background stars. ... The display stretches across Canada; just below it, in the middle of the picture, are the lights of Chicago, next to Lake Michigan. ... The Canadian scientific satellite Isis-2 (1971) carried an auroral imaging camera and discovered the diffuse aurora, a broad ribbon around the auroral oval, too spread-out to be noticed from the ground. ... Auroral Acceleration . ...

Astronomy Discussion Forums . ... Atm ћ Astrophotography ћ Blackholes ћ Blackholes2 ћ CCD ћ Celestron ћ Domes ћ Education . ... New Model: How Do The Sun And Moon Appear To Move Across The Sky . ... Post Message | ... focused on the Sun and the Moon as they appear from the given location of the Earth surface: . ... www.astronomy.net . About Astronomy Net | ... Forum posts are Copyright their authors as specified in the heading above the post. "dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET" . ...

Check out the new images (Jan 18-25) and (Jan 26-Feb 05) of the comet by Rob McNaught. ... Every few years a comet becomes bright enough to be easily seen with the naked eye but only every decade or so are these comparable with comets like Halley. ... Before Jan 13, the comet is not visible in the Australian sky after sunset. ... SOHO images . ... On Jan 12 at approximately 09:00 UT (8pm NSW time), comet C/2006 P1 McNaught appears at the 11 o'clock position in the images. ... STEREO images . ...

Next: A box, to include Up: To produce a region Previous: To produce a region . select cursor and circle . When in the image window, the mouse now has a box shape with an arrow at the upper left corner. The mouse buttons act as follows: . LEFT - to move the center of the circle at the position of the arrow point. ... RIGHT - idle. center the circle at the point source by positioning the arrow point and clicking on the LEFT mouse button. A circle will appear at the arrow position. ...

... Auroral Currents . ... 25c. Space tether . ... Aurora from Space . ... But the best view is still from space. ... The Canadian scientific satellite Isis-2 (1971) carried an auroral imaging camera and discovered the diffuse aurora, a broad ribbon around the auroral oval, too spread-out to be noticed from the ground. ... Currently, NASA's Polar (1996) collects images of the polar aurora using three cameras--in visible light (sometimes as frequently as 12 seconds apart), in ultra-violet and in x-rays. ...

... self-absorption - the absorption of light shining on an object by a process similar to that which produced the light originally; if a cloud emits less light than it absorbs from other clouds behind it, this net loss of light, termed self-absorption , causes the foreground cloud to appear darker than the background field (the term is from spectroscopy, where small absorption dips sometimes occur in larger emission lines, making the latter look as if it is absorbing part of itself) . ... HISA Main ...

... It is possible to change the meaning of keywords (to `overload' them), but it can be confusing, primarily because your new commands may not behave the same way that this manual claims. ... If you said box in your macro, then overloaded the keyword, you'd have a macro that called itself. ... Another example is that (when overloaded) lines saves the line numbers used, so that you can write a macro to print the top 10 lines of a file (it's called head ). ...

The Telescope:Pointing Data script takes set of pointing error measurements of pointing reference stars across the sky. ... To retry measuring the star, fix the problem (e.g. by adjusting focus, exposure time or offset) and press Continue . ... For each point in the az/alt grid the script will find and slew to a nearby pointing reference star, measure the star, write the pointing error to a data file whose path is displayed, and correct the pointing error. ...

Supernovae 2010jl in UGC 5189A . This page is devoted to information on Supernova 2010jl in UGC 5189A . ... Astronomy Magazine's Supernova SN 2010jl . ... Bad Astronomy's SN 2010 JL in weird UGC 5189 . SpaceBanter.com 2010jl post . Blogbaker's 2010jl post . Joseph Brimacombe widefield color image . ... 2010/11/04.50 . ... 2010/11/05.203 . ... Joseph Brimacombe . 2010/11/05.467 . ... mirror . ... JM Llapasset . ... 2011/01/15.160 . ... Back to Bright Supernovae - 2010 . ...

... 2004: . ... An increase in star brightness is followed by a decrease in asphericity and wind velocity to the point where stationary and even accreting fraction of the wind appears in extremely bright objects together with a flowing out fraction. ... Based on an analysis of observations obtained with BTA and on the published data it was found that degree of abnormality of energy distribution in continuum of magnetic chemically peculiar stars increases with an increase of their rotation period. ...

... This program was created for correlating chosen regions in the series of fts images. ... Chosen regions' . ... In this section the program counts the integral for each region of the grid for each image. ... As a matter of fact, the integral is total brightness of the region and it is counted by 'int_tabulated' IDL function. ... In addition, the program will show the count of the regions which correlate with the corresponding region (the brighter region means the bigger count) and its contour. ...