Terry's Astronomy Thread.

[Bluearrowll]

What's in the sky tonight?
April 13, 2013

-The thin crescent Moon floats between Aldebaran and the Pleiades in the west as twilight fades, with Jupiter above it, as shown at right.

-Be on the look out for auroras based off the large CME the sun launched on April 11. The CME is expected to reach Earth at some point today. Pay attention to the aurora tracker as the day progresses.

Astro Picture of the Day:
April 13, 2013

Source
This week the Sun gave up its strongest solar flare so far in 2013, accompanied by a coronal mass ejection (CME) headed toward planet Earth. A false-color composite image in extreme ultraviolet light from the Solar Dynamics Observatory captures the moment, recorded on April 11 at 0711 UTC. The flash, a moderate, M6.5 class flare erupting from active region AR 11719, is near the center of the solar disk. Other active regions, areas of intense magnetic fields seen as sunspot groups in visible light, mottle the surface as the solar maximum approaches. Loops and arcs of glowing plasma trace the active regions' magnetic field lines. A massive cloud of energetic, charged particles, the CME will impact the Earth's magnetosphere by this weekend and skywatchers should be on the alert for auroral displays.

[Bluearrowll]

What's in the sky tonight?
April 14, 2013

-The Moon and Jupiter shine side by side high in the west after dusk, 3° or 4° apart, with Aldebaran below them. Although they look close together, the Moon is 1.3 light-seconds from Earth, Jupiter is currently 47 light-minutes distant, and Aldebaran is 65 light-years in the background.

Astro Picture of the Day:
April 14, 2013

Source
Gliding silently through the outer Solar System, the Voyager 2 spacecraft camera captured Neptune and Triton together in crescent phase in 1989. The elegant picture of the gas giant planet and its cloudy moon was taken from behind just after closest approach. It could not have been taken from Earth because Neptune never shows a crescent phase to sunward Earth. The unusual vantage point also robs Neptune of its familiar blue hue, as sunlight seen from here is scattered forward, and so is reddened like the setting Sun. Neptune is smaller but more massive than Uranus, has several dark rings, and emits more light than it receives from the Sun.

[Bluearrowll]

What's in the sky tonight?
April 15, 2013

-The Moon right after dark is in the top of Orion's very dim Club. That's not far from the center of the huge Winter Hexagon: Sirius, Procyon, the Pollux-and-Castor pair, Capella, Aldebaran (under Jupiter), Rigel, and back to Sirius.

-Jupiter (magnitude –2.1, in Taurus) is the first "star" to come out in the west after sunset. It descends through the evening and sets around 11 or midnight. Below Jupiter is orange Aldebaran. Farther to Jupiter's lower right are the Pleiades. In a telescope, Jupiter has shrunk to just 35 arcseconds wide.

News Posted Today:
April 12, 2013
The Most Distant Star Ever Seen?



Astro Picture of the Day:
April 15, 2013

Source
Stars are forming in the Soul of the Queen of Aethopia. More specifically, a large star forming region called the Soul Nebula can be found in the direction of the constellation Cassiopeia, who Greek mythology credits as the vain wife of a King who long ago ruled lands surrounding the upper Nile river. The Soul Nebula houses several open clusters of stars, a large radio source known as W5, and huge evacuated bubbles formed by the winds of young massive stars. Located about 6,500 light years away, the Soul Nebula spans about 100 light years and is usually imaged next to its celestial neighbor the Heart Nebula (IC 1805). The above image appears mostly red due to the emission of a specific color of light emitted by excited hydrogen gas.

[Bluearrowll]

What's in the sky tonight?
April 16, 2013

-Look left of the Moon after dark for Procyon. High above the Moon is Pollux, with Castor at its right. Equally far below the Moon is Betelgeuse, the top corner of Orion.

-Saturn (magnitude +0.2, in Libra) glows low in the east-southeast by the end of twilight. Look for it well to the lower left of Spica, and farther lower right of brighter Arcturus. Saturn rises higher all evening. It shines highest in the south around 1 or 2 a.m. daylight saving time — more or less between Spica to its right, and Delta Scorpii (and then Antares) farther to its lower left. Saturn will reach opposition on the night of April 27th.

Astro Picture of the Day:
April 16, 2013

Source
One of the brightest galaxies in planet Earth's sky is similar in size to our Milky Way Galaxy: big, beautiful M81. This grand spiral galaxy lies 11.8 million light-years away toward the northern constellation of the Great Bear (Ursa Major). The deep image of the region reveals details in the bright yellow core, but at the same time follows fainter features along the galaxy's gorgeous blue spiral arms and sweeping dust lanes. It also follows the expansive, arcing feature, known as Arp's loop, that seems to rise from the galaxy's disk at the upper right. Studied in the 1960s, Arp's loop has been thought to be a tidal tail, material pulled out of M81 by gravitational interaction with its large neighboring galaxy M82. But a subsequent investigation demonstrates that at least some of Arp's loop likely lies within our own galaxy. The loop's colors in visible and infrared light match the colors of pervasive clouds of dust, relatively unexplored galactic cirrus only a few hundred light-years above the plane of the Milky Way. Along with the Milky Way's stars, the dust clouds lie in the foreground of this remarkable view. M81's dwarf companion galaxy, Holmberg IX, can be seen just above the large spiral. On the sky, this image spans about 0.5 degrees, about the size of the Full Moon.

[Bluearrowll]

What's in the sky tonight?
April 17, 2013

-The Moon this evening is passing almost midway between Procyon to its lower left and Pollux to its upper right. Castor, slightly dimmer, shines to the right of Pollux.

Astro Picture of the Day:
April 17, 2013

Source
An expanded view from yesterday's picture, Large galaxies and faint nebulae highlight this deep image of the M81 Group of galaxies. First and foremost in the wide-angle 12-hour exposure is the grand design spiral galaxy M81, the largest galaxy visible in the image. M81 is gravitationally interacting with M82 just below it, a big galaxy with an unusual halo of filamentary red-glowing gas. Around the image many other galaxies from the M81 Group of galaxies can be seen. Together with other galaxy congregates including our Local Group of galaxies and the Virgo Cluster of galaxies, the M81 Group is part of the expansive Virgo Supercluster of Galaxies. This whole galaxy menagerie is seen through the faint glow of an Integrated Flux Nebula, a little studied complex of diffuse gas and dust clouds in our Milky Way Galaxy.

[Bluearrowll]

What's in the sky tonight?
April 18, 2013

-The Moon is exactly first quarter at 8:31 a.m. EDT this morning, which means it looks equally "first quarter" on the evenings of the 17th and 18th from North America's eastern time zones. The Moon this evening is in dim Cancer, inside the big, long triangle of Procyon, Pollux, and Regulus.

Astro Picture of the Day:
April 18, 2013

Source
What kind of cloud is next to that mountain? A lenticular. This type of cloud forms in air that passes over a mountain, rises up again, and cools past the dew point -- so what molecular water carried in the air condenses into droplets. The layered nature of some lenticular clouds may make them appear, to some, as large alien spaceships. In this case, the mountain pictured is Mt. Hood located in Oregon, USA. Lenticular clouds can only form when conditions are right - for example this is first time this astrophotographer has seen a lenticular cloud at night near Mt. Hood. The above image was taken in mid-March about two hours before dawn.

[Bluearrowll]

What's in the sky tonight?
April 19, 2013

-Look for Regulus and the Sickle of Leo to the left of the Moon this evening, as shown here.

Astro Picture of the Day:
April 19, 2013

Source
Sculpted by stellar winds and radiation, the star factory known as Messier 17 lies some 5,500 light-years away in the nebula-rich constellation Sagittarius. At that distance, this degree wide field of view spans almost 100 light-years. The sharp, composite, color image utilizing data from space and ground based telescopes, follows faint details of the region's gas and dust clouds against a backdrop of central Milky Way stars. Stellar winds and energetic light from hot, massive stars formed from M17's stock of cosmic gas and dust have slowly carved away at the remaining interstellar material producing the cavernous appearance and undulating shapes. M17 is also known as the Omega Nebula or the Swan Nebula.

[Bluearrowll]

What's in the sky tonight?
April 20, 2013

-The Moon now shines under Regulus after dark.

-Be on the lookout for the Lyrid Meteor Shower, slated to peak tomorrow.

-Saturn (magnitude +0.1, in Libra) is nearing opposition. It glows low in the east-southeast as twilight fades, well to the lower left of Spica and farther lower right of brighter Arcturus. Saturn rises higher all evening and shines highest in the south around 1 a.m. daylight saving time. It's at opposition on the night of April 27th.

-Carefully note the brightness of Saturn's rings with respect to the globe. Keep watch. The rings brighten for a few days around opposition due to the Seeliger effect: the solid particles of the rings preferentially reflect sunlight back in the direction it came from, more than Saturn's cloudtops do.

-Below is Saturn on April 15th, imaged by Christopher Go in the Philippines using a Celestron 14 scope and a Point Grey Research monochrome Flea3 (ICX618) camera with Chroma Technology LRGB color filters. South is up. "The polar hexagon is prominent on this image," he writes. "Note the white spots on the North North Temperate Zone."

News Posted Today:
April 19, 2013
A Tumbling Apophis: Good News for Earth


Astro Picture of the Day:
April 20, 2013

Source
As far as the eye could see, it was a dark night at Las Campanas Observatory in the southern Atacama desert of Chile. But near local midnight on April 11, this mosaic of 3 minute long exposures revealed a green, unusually intense, atmospheric airglow stretching over thin clouds. Unlike aurorae powered by collisions with energetic charged particles and seen at high latitudes, the airglow is due to chemiluminescence, the production of light in a chemical reaction, and found around the globe. The chemical energy is provided by the Sun's extreme ultraviolet radiation. Like aurorae, the greenish hue of this airglow does originate at altitudes of 100 kilometers or so dominated by emission from excited oxygen atoms. The gegenschein, sunlight reflected by dust along the solar system's ecliptic plane was still visible on that night, a faint bluish cloud just right of picture center. At the far right, the Milky Way seems to rise from the mountain top perch of the Magellan telescopes. Left are the OGLE project and du Pont telescope domes.

[Bluearrowll]

What's in the sky tonight?
April 21, 2013

-The Lyrid meteor shower should peak before dawn Monday morning local time. Most years it's quite weak, but there have been surprises.

-This year the light of the nearly full Moon will interfere, but at least you can determine whether or not an outburst is in progress at the times you're looking. Watch late on the night of April 21st or before dawn's first light on April 22nd, when the shower's radiant (near Vega) is high in the sky.

Astro Picture of the Day:
April 21, 2013

Source
Do you see it? This common question frequently precedes the rediscovery of one of the most commonly recognized configurations of stars on the northern sky: the Big Dipper. This grouping of stars is one of the few things that has likely been seen, and will be seen, by every generation. The Big Dipper is not by itself a constellation. Although part of the constellation of the Great Bear (Ursa Major), the Big Dipper is an asterism that has been known by different names to different societies. Five of the Big Dipper stars are actually near each other in space and were likely formed at nearly the same time. Connecting two stars in the far part of the Big Dipper will lead one to Polaris, the North Star, which is part of the Little Dipper. Relative stellar motions will cause the Big Dipper to slowly change its apparent configuration over the next 100,000 years.

[Bluearrowll]

What's in the sky tonight?
April 22, 2013

-The two brightest points in the sky after dusk this week are Jupiter in the west and Sirius in the southwest. Midway between them is Orion. This lineup is lying down lower every week now. How late into the spring can you keep it in view?.

Astro Picture of the Day:
April 22, 2013

Source
While drifting through the cosmos, a magnificent interstellar dust cloud became sculpted by stellar winds and radiation to assume a recognizable shape. Fittingly named the Horsehead Nebula, it is embedded in the vast and complex Orion Nebula (M42). A potentially rewarding but difficult object to view personally with a small telescope, the above gorgeously detailed image was recently taken in infrared light by the orbiting Hubble Space Telescope in honor of the 23rd anniversary of Hubble's launch. The dark molecular cloud, roughly 1,500 light years distant, is cataloged as Barnard 33 and is seen above primarily because it is backlit by the nearby massive star Sigma Orionis. The Horsehead Nebula will slowly shift its apparent shape over the next few million years and will eventually be destroyed by the high energy starlight.

[Bluearrowll]

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]

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]

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]

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]

Originally Posted by Bluearrowll

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]

Originally Posted by Riotpolice

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]

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]

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]

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]

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.