Terry's Astronomy Thread.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 23, 2013

-There's a bright gibbous Moon tonight. If you're out with a telescope, you'll notice that the Moon is creeping toward a star: Chi Virginis, magnitude 4.7. The Moon's invisible dark limb, just beyond the terminator, will occult the star for most of North America except the Northeast and north of the Great Lakes. Some times of the star's disappearance: at Washington, DC, 12:20 a.m. EDT; Miami, 11:58 p.m. EDT; Chicago, 10:47 p.m. CDT; Austin, 10:17 p.m. CDT; Denver, 9:07 p.m. MDT; Los Angeles, 7:52 p.m. PDT.

Astro Picture of the Day:
April 23, 2013

Source
What looks like a puff-ball is surely the remains of the brightest supernova in recorded human history. In 1006 AD, it was recorded as lighting up the nighttime skies above areas now known as China, Egypt, Iraq, Italy, Japan, and Switzerland. The expanding debris cloud from the stellar explosion, found in the southerly constellation the Wolf (Lupus), still puts on a cosmic light show across the electromagnetic spectrum. In fact, the above image results from three colors of X-rays taken by the orbiting Chandra X-ray Observatory. Now known as the SN 1006 supernova remnant, the debris cloud appears to be about 60 light-years across and is understood to represent the remains of a white dwarf star. Part of a binary star system, the compact white dwarf gradually captured material from its companion star. The buildup in mass finally triggered a thermonuclear explosion that destroyed the dwarf star. Because the distance to the supernova remnant is about 7,000 light-years, that explosion actually happened 7,000 years before the light reached Earth in 1006. Shockwaves in the remnant accelerate particles to extreme energies and are thought to be a source of the mysterious cosmic rays.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 24, 2013

-Look close to the nearly full Moon for Spica tonight. The Moon occults Spica for parts of Central America, South America, and southern Africa.

Astro Picture of the Day:
April 24, 2013

Source
What happens if you wring out a wet towel while floating in space? The water shouldn't fall toward the floor because while orbiting the Earth, free falling objects will appear to float. But will the water fly out from the towel, or what? The answer may surprise you. To find out and to further exhibit how strange being in orbit can be, Expedition 35 Commander Chris Hadfield did just this experiment last week in the microgravity of the Earth orbiting International Space Station. As demonstrated in the above video, although a few drops do go flying off, most of the water sticks together and forms a unusual-looking cylindrical sheath in and around the towel. The self-sticking surface tension of water is well known on Earth, for example being used to create Artistic Water cascades and, more generally, raindrops.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 25, 2013

-Full Moon. A very slight partial lunar eclipse is visible from Europe, Africa, Australia, and most of Asia, centered on 20:07 April 25th Universal Time. Details are here: http://eclipse.gsfc.nasa.gov/OH/OH20...l#LE2013Apr25P

The "star" near the Moon all night is Saturn, just two days away from its own opposition.

Astro Picture of the Day:
April 25, 2013

Source
The dark, inner shadow of planet Earth is called the umbra. Shaped like a cone extending into space, it has a circular cross section and is most easily seen during a lunar eclipse. But the complete cross section is larger than the Moon's angular size in the stages of an eclipse. Still, this thoughtful composite illustrates the full extent of the circular shadow by utilizing images from both partial and total eclipses passing through different parts of the umbra. The images span the years 1997 to 2011, diligently captured with the same optics, from Voronezh, Russia. Along the bottom and top are stages of the partial lunar eclipses from September 2006 and August 2008 respectively. In the rightside bottom image, the Moon is entering the umbra for the total eclipse of September 1997. At left bottom, the Moon leaves the umbra after totality in May 2004. Middle right, center, and left, are stages of the total eclipse of June 2011, including the central, deep red total phase. During today's brief partial lunar eclipse seen only from the eastern hemisphere, the Moon will just slightly graze the umbra's lower edge.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 26, 2013

-Around the end of twilight this evening, the Moon rises below Saturn. With binoculars, look closer below Saturn for the wide double star Alpha2 and Alpha1 Librae, magnitudes 2.8 and 5.2, respectively.

Astro Picture of the Day:
April 26, 2013

Source
Our solar system's miasma of incandescent plasma, the Sun may look a little scary here. The picture is a composite of 25 images recorded in extreme ultraviolet light by the orbiting Solar Dynamics Observatory between April 16, 2012 and April 15, 2013. The particular wavelength of light, 171 angstroms, shows emission from highly ionized iron atoms in the solar corona at a characteristic temperatures of about 600,000 kelvins (about 1 million degrees F). Girdling both sides of the equator during the approach to maximum in its 11-year solar cycle, the solar active regions are laced with bright loops and arcs along magnetic field lines. Of course, a more familiar visible light view would show the bright active regions as groups of dark sunspots. Three years of Solar Dynamics Observatory images are compressed into this short video.

[Riotpolice]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 26, 2013

-Around the end of twilight this evening, the Moon rises below Saturn. With binoculars, look closer below Saturn for the wide double star Alpha2 and Alpha1 Librae, magnitudes 2.8 and 5.2, respectively.

Astro Picture of the Day:
April 26, 2013

Source
Our solar system's miasma of incandescent plasma, the Sun may look a little scary here. The picture is a composite of 25 images recorded in extreme ultraviolet light by the orbiting Solar Dynamics Observatory between April 16, 2012 and April 15, 2013. The particular wavelength of light, 171 angstroms, shows emission from highly ionized iron atoms in the solar corona at a characteristic temperatures of about 600,000 kelvins (about 1 million degrees F). Girdling both sides of the equator during the approach to maximum in its 11-year solar cycle, the solar active regions are laced with bright loops and arcs along magnetic field lines. Of course, a more familiar visible light view would show the bright active regions as groups of dark sunspots. Three years of Solar Dynamics Observatory images are compressed into this short video.

That's beautiful.

EDIT: You should post the video too; it's pretty awesome that you can see the magnetic fields if you look closely. 3 Years of work compiled into one 4 minute video wow.

[Bluearrowll]

Re: Terry's Astronomy Thread.

That's beautiful.

EDIT: You should post the video too; it's pretty awesome that you can see the magnetic fields if you look closely. 3 Years of work compiled into one 4 minute video wow.

Done. Thanks for the recommendation!

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 27, 2013

-The waning gibbous Moon rises in the southeast very late this evening, with the red supergiant Antares sparkling to its right. By early dawn Sunday morning Antares is below the Moon in the southwest.

-Saturn (magnitude +0.1, in Libra) is at opposition Saturday night April 27th. All week it glows low in the east-southeast as twilight fades (to the lower left of Spica and farther lower right of Arcturus). It rises it higher all evening and shines highest in the south in the middle of the night.

-Carefully note the brightness of the rings with respect to the globe. The rings always brighten for several days around opposition due to the Seeliger effect. The solid, very irregular particles of the rings preferentially reflect sunlight back in the direction it came from more than Saturn's cloudtops do. Watch as the rings dim back down later in the week, as Saturn moves away from the opposition point in Earth's sky.

-The Seeliger effect: Christopher Go took these images of Saturn on March 2nd (top) and April 24th. Notice how the rings brightened with respect to the globe. And on the 24th, Saturn was still three days from opposition.

Astro Picture of the Day:
April 27, 2013

Source
Get out your red/blue glasses and gaze across the floor of Gale crater on Mars. From your vantage point on the deck of the Curiosity Rover Mount Sharp, the crater's 5 kilometer high central mountain looms over the southern horizon. Poised in the foreground is the rover's robotic arm with tool turret extended toward the flat veined patch of martian surface dubbed "John Klein". A complete version of the stereo view spans 360 degrees, digitally stitched together from the rover's left and right navigation camera frames taken in late January. The layered lower slopes of Mount Sharp, formally known as Aeolis Mons, are a future destination for Curiosity. Find the complete version here: http://photojournal.jpl.nasa.gov/catalog/PIA16925

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 28, 2013

-The classic small-scope binary star Gamma Virginis, or Porrima, shines upper right of Spica, 14° from it (about a fist and a half at arm's length) these evenings. Porrima's two equal components were almost unresolvably close together for much of the last decade, but this spring they've widened to 2 arcseconds apart. Use high power.

-Venus (magnitude –3.9) is just beginning an evening apparition that will continue for the rest of the year. How soon can you first pick it up? Use binoculars to look for Venus a mere 15 or 20 minutes after sunset, barely above the west-northwest horizon. It's far to the lower right of Jupiter for viewers at mid-northern latitudes.

Astro Picture of the Day:
April 28, 2013

Source
It was one of the largest and longest lived storms ever recorded in our Solar System. First seen in late 2010, the above cloud formation in the northern hemisphere of Saturn started larger than the Earth and soon spread completely around the planet. The storm was tracked not only from Earth but from up close by the robotic Cassini spacecraft currently orbiting Saturn. Pictured above in false colored infrared in February, orange colors indicate clouds deep in the atmosphere, while light colors highlight clouds higher up. The rings of Saturn are seen nearly edge-on as the thin blue horizontal line. The warped dark bands are the shadows of the rings cast onto the cloud tops by the Sun to the upper left. A source of radio noise from lightning, the intense storm was thought to relate to seasonal changes when spring emerges in the north of Saturn. After raging for over six months, the iconic storm circled the entire planet and then tried to absorb its own tail - which surprisingly caused it to fade away.

This set of images from NASA's Cassini mission shows the evolution of a massive thunder-and-lightning storm that circled all the way around Saturn and fizzled when it ran into its own tail. The storm was first detected on Dec. 5, 2010.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 29, 2013

-It's almost May, yet the winter star Sirius still twinkles low above the west-southwest horizon in late twilight. How much later into the spring can you keep it in view?

-With your telescope, do you ever observe the lunar landscape when the Moon is waning before dawn and the terminator is lunar sunset rather than sunrise? Get up early this week and have a look at familiar features in this new light.

News Posted Today:
April 26, 2013
See Saturn at Its Best for 2013


Astro Picture of the Day:
April 29, 2013

Source
What's that next to the Milky Way? An unusual natural rock formation known as Roque Cinchado or Stone Tree found on the Spanish Canary Island of Tenerife. A famous icon, Roque Cinchado is likely a dense plug of cooled volcanic magma that remains after softer surrounding rock eroded away. Majestically, the central band of our Milky Way Galaxy is visible arcing across the right of the above seven image panoramic mosaic taken during the summer of 2010. On the far right is the Teide volcano complete with a lenticular cloud hovering near its peak.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
April 30, 2013

-The small but distinctive constellation Corvus, the Crow, is an icon of spring evenings (in the Northern Hemisphere). Look for its four-star quadrilateral in the south-southeast after dark, to the right of Saturn and Spica.

-Mars remains hidden in the glare of the Sun. Not until summer will it emerge in the dawn.

News Posted Today:
April 29, 2013
Herschel Breathes Its Last


Astro Picture of the Day:
April 30, 2013

Source
What spacecraft is humanity currently using to explore our Solar System? Presently, every inner planet has at least one robotic explorer, while several others are monitoring our Sun, some are mapping Earth's Moon, a few are chasing asteroids and comets, one is orbiting Saturn, and several are even heading out into deep space. The above illustration gives more details, with the inner Solar System depicted on the upper right and the outer Solar System on the lower left. Given the present armada, our current epoch might become known as the time when humanity first probed its own star system. Sometimes widely separated spacecraft act together as an InterPlanetary Network to determine the direction of distant explosions by noting when each probe detects high energy photons. Future spacecraft milestones, as indicated along the bottom of the graphic, include Dawn reaching Ceres, the largest object in the asteroid belt, and New Horizons reaching Pluto, both in 2015.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
May 1, 2013

-Jupiter (magnitude –2.0, in Taurus) is the first "star" to come out in the west after sunset, a little lower every day. It descends in the evening and sets around 10 or 11 p.m. Below Jupiter twinkles orange Aldebaran, and a similar distance above Jupiter is El Nath (Beta Tauri). Bright Capella shines to the upper right from there. In a telescope, Jupiter has shrunk to a disappointing 34 arcseconds wide.

News Posted Today:
April 29, 2013
One Gap, No Planets


Astro Picture of the Day:
May 1, 2013

Source
This huge ball of stars predates our Sun. Long before humankind evolved, before dinosaurs roamed, and even before our Earth existed, ancient globs of stars condensed and orbited a young Milky Way Galaxy. Of the 200 or so globular clusters that survive today, Omega Centauri is the largest, containing over ten million stars. Omega Centauri is also the brightest globular cluster, at apparent visual magnitude 3.9 it is visible to southern observers with the unaided eye. Cataloged as NGC 5139, Omega Centauri is about 18,000 light-years away and 150 light-years in diameter. Unlike many other globular clusters, the stars in Omega Centauri show several different ages and trace chemical abundances, indicating that the globular star cluster has a complex history over its 12 billion year age.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
May 2, 2013

-Last-quarter Moon. The Moon, between dim Capricornus and Aquarius, rises around the middle of the night (far below Altair). By daybreak Friday morning it's high in the south.

News Posted Today:
May 1, 2013
Saturn is Making Waves


Astro Picture of the Day:
May 2, 2013

Source
Acquiring its first sunlit views of far northern Saturn late last year, the Cassini spacecraft's narrow-angle camera recorded this stunning image of the vortex at the ringed planet's north pole. The false color, near-infrared image results in red hues for low clouds and green for high ones, causing the north-polar hurricane to take on the appearance of a rose. Enormous by terrestrial hurricane standards, this storm's eye is about 2,000 kilometers wide, with clouds at the outer edge traveling at over 500 kilometers per hour. The north pole Saturn hurricane swirls inside the large, six-sided weather pattern known as the hexagon. Of course, in 2006 Cassini also imaged the hurricane at Saturn's south pole.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
May 3, 2013

-As soon as it's fully dark, look for the Big Dipper very high in the north-northeast. It's upside down, with its handle to the right and its bowl to the left. It's "dumping water" onto the much dimmer Little Dipper down below.

Astro Picture of the Day:
May 3, 2013

Source
Combined image data from the massive, ground-based VISTA telescope and the Hubble Space Telescope was used to create this wide perspective of the interstellar landscape surrounding the famous Horsehead Nebula. Captured at near-infrared wavelengths, the region's dusty molecular cloud sprawls across the scene that covers an angle about two-thirds the size of the Full Moon on the sky. Left to right the frame spans just over 10 light-years at the Horsehead's estimated distance of 1,600 light-years. Also known as Barnard 33, the still recognizable Horsehead Nebula stands at the upper right, the near-infrared glow of a dusty pillar topped with newborn stars. Below and left, the bright reflection nebula NGC 2023 is itself the illuminated environs of a hot young star. Dense clouds below the base of the Horsehead and on the outskirts of NGC 2023 show the tell-tale far red emission of energetic jets, known as Herbig-Haro objects, also associated with newborn stars.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
May 4, 2013

-The three brightest stars in the May dusk are all zero magnitude: Capella in the northwest, Vega lower in the northeast, and Arcturus high in the east. (Jupiter, far lower left of Capella, is brighter but doesn't count.)

-The Eta Aquariid meteor shower, usually the year's best for the Southern Hemisphere, should be strongest just before dawn. Fewer of its meteors can be seen from the latitudes of the southern U.S., and few or none from the northern U.S. and Europe.

News Posted Today
May 3, 2013
Lingering Echoes of Comet S-L 9's Demise


Astro Picture of the Day:
May 4, 2013

Source
Last week, as the Sun set a Full Moon rose over the springtime landscape of Tihany, Hungary on the northern shores of Lake Balaton. As it climbed into the clear sky, the Moon just grazed the dark, umbral shadow of planet Earth in the year's first partial lunar eclipse. The partial phase, seen near the top of this frame where the lunar disk is darkened along the upper limb, lasted for less than 27 minutes. Composited from consecutive exposures, the picture presents the scene's range of natural colors and subtle shading apparent to the eye. At next week's New Moon, the season's celestial shadow play will continue with an annular solar eclipse, the path of annularity tracking through northern Australia and the central Pacific.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
May 5, 2013

-The western Arch of Spring is on fine display in late twilight. Its top consists of Pollux and Castor high in the west. They're lined up roughly horizontally and are about three finger-widths at arm's length apart. Look far to their lower left for Procyon, and farther to their lower right for brighter Capella.

-Far below the arch this spring, two more points make it a pentagon. These are bright Jupiter and, about two fists to Jupiter's left, Betelgeuse.

Astro Picture of the Day:
May 5, 2013

Source
Is that a spaceship or a cloud? Although it may seem like an alien mothership, it's actually a impressive thunderstorm cloud called a supercell. Such colossal storm systems center on mesocyclones - rotating updrafts that can span several kilometers and deliver torrential rain and high winds including tornadoes. Jagged sculptured clouds adorn the supercell's edge, while wind swept dust and rain dominate the center. A tree waits patiently in the foreground. The above supercell cloud was photographed in July west of Glasgow, Montana, USA, caused minor damage, and lasted several hours before moving on.