Terry's Astronomy Thread.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
June 26, 2012

-First-quarter Moon this evening (exact at 11:30 p.m. EDT). The Moon shines in Virgo, below the line from Saturn to Mars.

-Mercury (about magnitude 0.0 and fading) is low in the west-northwest about 40 to 60 minutes after sundown. Well to its right are fainter Pollux and Castor.

Astro Picture of the Day:
June 26, 2012

Source:
What time is it? If the time and day are right, this sundial will tell you: SOLSTICE. Only then will the Sun be located just right for sunlight to stream through openings and spell out the term for the longest and shortest days of the year. And that happened last week and twice each year. The sundial was constructed by Jean Salins in 1980 and is situated at the Ecole Supérieure des Mines de Paris in Valbonne Sophia Antipolis of south-eastern France. On two other days of the year, watchers of this sundial might get to see it produce another word: EQUINOXE.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
June 27, 2012

-The Moon forms a nice triangle with Saturn and Spica this evening, as shown here.

-This is the Latest sunset of the year (at 40° north latitude) even though the solstice and longest day were on June 20th.

Astro Picture of the Day:
June 27, 2012

Source:
When stars form, pandemonium reigns. A particularly colorful case is the star forming region Simeis 188 which houses an unusual and bright cloud arc cataloged as NGC 6559. Visible above are red glowing emission nebulas of hydrogen, blue reflection nebulas of dust, dark absorption nebulas of dust, and the stars that formed from them. The first massive stars formed from the dense gas will emit energetic light and winds that erode, fragment, and sculpt their birthplace. And then they explode. The resulting morass can be as beautiful as it is complex. After tens of millions of years, the dust boils away, the gas gets swept away, and all that is left is a naked open cluster of stars. Simeis 188 is located about 4,000 light years away and can be found about one degree northeast of M8, the Lagoon Nebula.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
June 28, 2012

-Saturn and Spica are now to the right of the waxing gibbous Moon.

-Have you spotted Jupiter and Venus low in the dawn yet? They're getting higher and easier every day.

Astro Picture of the Day:
June 28, 2012

Source:
The glare of Alpha Centauri, one of the brightest stars in planet Earth's night sky, floods the left side of this southern skyscape. A mere 4.3 light-years distant, Alpha Centauri actually consists of two component stars similar in size to the Sun, locked in a mutual orbit. Much smaller and cooler, a third member of the same star system, Proxima Centauri, lies outside this field of view. Still, the telescopic scene does reveal often overlooked denizens of the Milky Way's crowded galactic plane that lie beyond the glare of Alpha Centauri, including a planetary nebula cataloged as Hen 2-111, an estimated 7,800 light-years away. The gaseous shroud of a dying star, the nebula's brighter core and fainter halo of reddish ionized gas span over twenty light-years, seen just right of picture center. Farther right are two notable open clusters of stars, the compact Pismis 19 also nearly 8,000 light-years away whose light is reddened by intervening dust, and the looser, closer NGC 5617. Just visible in the glare of Alpha Centauri is the dim glow of a shell-like supernova remnant, above and right of the closest star system's bright core.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
June 29, 2012

-Now that June is about to turn into July, the Teapot of Sagittarius is up and sitting level low in the southeast after the sky becomes fully dark

-Venus, Jupiter, and the Pleiades make a vertical line in the morning dawn today.

Astro Picture of the Day:
June 29, 2012

Source:
Part of a dark expanse that splits the crowded plane of our Milky Way galaxy, the Aquila Rift arcs through the northern hemisphere's summer skies near bright star Altair and the Summer Triangle In silhouette against the Milky Way's faint starlight, its dusty molecular clouds likely contain raw material to form hundreds of thousands of stars and astronomers eagerly search the clouds for telltale signs of star birth. This telescopic close-up looks toward the region at a fragmented Aquila dark cloud complex identified as LDN 673, stretching across a field of view slightly wider than the full moon. In the scene, visible indications of energetic outflows associated with young stars include the small red tinted nebulosity RNO 109 at top left and Herbig-Haro object HH32 above and right of center. The dark clouds in Aquila are estimated to be some 600 light-years away. At that distance, this field of view spans about 7 light-years.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
June 30, 2012

-The Moon shines in the head stars of Scorpius this evening, with Antares to its lower left.

-Remember when Venus and Jupiter paired up spectacularly in the evening last March? Now they're at it again, but this time low in the dawn, as shown at right. Best time: about an hour or so before your local sunrise.

-A leap second will be inserted into the world's civil time systems at the end of June 30th Coordinated Universal Time (the second before 8:00 p.m. Eastern Daylight Time). The minute 23:59 UTC will have 61 seconds, not 60, to adjust for a slight accumulated slowdown in Earth's spin. The last leap second was added to the world's clocks at the end of 2008. As the moment arrives, watch your favourite online time service and see if they get it right.

Astro Picture of the Day:
June 30, 2012

Source:
Now shining in eastern skies at dawn, bright planets Venus and Jupiter join the Pleiades star cluster in this sea and sky scape, recorded earlier this week near Buenos Aires, Argentina. Venus dominates the scene that includes bright star Aldebaran just below and to the right. The planets are easy to spot for early morning risers, but this sky also holds two of our solar system's small worlds, Vesta and Ceres, not quite bright enough to be seen with the unaided eye. The digital camera's time exposure just captures them, though. Their positions are indicated when you put your cursor over the image. In orbit around Vesta, NASA's Dawn spacecraft arrived there last July, but is nearing the end of its visit to the main belt asteroid. In August, it will set off on its planned journey to Ceres, arriving at the dwarf planet in 2015.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
July 1, 2012

-As soon as the stars come out, look high in the northwest for the Big Dipper hanging straight down by its handle. As night advances, the Dipper dips lower and to the right as if to scoop up water.

-In the early morning hours about 1 hour before sunrise, look for Aldebaran of the Hyades, Venus in the Hyades, Jupiter, and the Pleiades to be in a near vertical line, rising higher in the sky as dawn brightens.

Astro Picture of the Day:
July 1, 2012

Source:
This image shows the Large Magellanic Cloud galaxy in infrared light as seen by the Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions, and NASA's Spitzer Space Telescope. In the instruments' combined data, this nearby dwarf galaxy looks like a fiery, circular explosion. Rather than fire, however, those ribbons are actually giant ripples of dust spanning tens or hundreds of light-years. Significant fields of star formation are noticeable in the center, just left of center and at right. The brightest center-left region is called 30 Doradus, or the Tarantula Nebula, for its appearance in visible light.

The colors in this image indicate temperatures in the dust that permeates the Cloud. Colder regions show where star formation is at its earliest stages or is shut off, while warm expanses point to new stars heating surrounding dust. The coolest areas and objects appear in red, corresponding to infrared light taken up by Herschel's Spectral and Photometric Imaging Receiver at 250 microns, or millionths of a meter. Herschel's Photodetector Array Camera and Spectrometer fills out the mid-temperature bands, shown here in green, at 100 and 160 microns. The warmest spots appear in blue, courtesy of 24- and 70-micron data from Spitzer.

Herschel is a European Space Agency mission with significant NASA contributions. Launched in 2009, the spacecraft carries science instruments provided by consortia of European institutes. NASA's Herschel Project Office based at JPL contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the U.S. astronomical community. Caltech manages JPL for NASA.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
July 2, 2012

-Vega is the brightest star very high in the east after dark. Deneb is the brightest to its lower left. Altair is farther to Vega's lower right. These three form the big Summer Triangle.

-Mars (magnitude +0.8, in Virgo) glows orange in the west-southwest at dusk and lower in the west later. It's still about 22° from the Saturn-and-Spica pair to its left, but it's heading their way. Mars will pass right between them in mid-August.

In a telescope Mars is gibbous and very tiny (6.6 arcseconds wide), continuing to fade and shrink.

Astro Picture of the Day:
July 2, 2012

Source:
What causes the surrounding shells in peculiar galaxy Cen A? In 2002 a fascinating image of peculiar galaxy Centaurus A was released, processed to highlight a faint blue arc indicating an ongoing collision with a smaller galaxy. Another interesting feature of Cen A, however, is the surrounding system of shells, better visible here in this recently released wider pan from the four meter Blanco telescope at Cerro Tololo Inter-American Observatory. Faint shells around galaxies are not unusual and considered by themselves as evidence of a previous galaxy merger, analogous to water ripples on a pond. An unexpected attribute of these shells is the abundance of gas, which should become separated from existing stars during the collision.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
July 3, 2012

-The full Moon shines in the southeast after dark. The bright star far to its upper left is Altair. Look just above Altair, by about a finger-width at arm's length, for fainter Tarazed (Gamma Aquilae). Tarazed, an orange giant, is much more luminous than Altair but is almost 20 times farther away (330 light-years, compared to Altair's distance of 17 light-years).

-Venus and Jupiter (magnitudes –4.7 and –2.1) shine low in the east-northeast during dawn. They're stacked 5° apart with Jupiter on top, as shown at the top of this page. Watch Aldebaran, much fainter, closing in on Venus from below. In Venus's starry background are the Hyades, while the Pleiades pose above Jupiter. Bring binoculars and look early!

Astro Picture of the Day:
July 3, 2012

Source:
Humanity's robot orbiting Saturn has recorded yet another amazing view. That robot, or course, is the spacecraft Cassini, while the new amazing view includes a bright moon, thin rings, oddly broken clouds, and warped shadows. Titan, Saturn's largest moon, appears above as a featureless tan as it is continually shrouded in thick clouds. The rings of Saturn are seen as a thin line because they are so flat and imaged nearly edge on. Details of Saturn's rings are therefore best visible in the dark ring shadows visible across the giant planet's cloud tops. Since the ring particles orbit in the same plane as Titan, they appear to skewer the foreground moon, In the upper hemisphere of Saturn, the clouds show many details, including dips in long bright bands indicating disturbances in a high altitude jet stream. Recent precise measurements of how much Titan flexes as it orbits Saturn hint that vast oceans of water might exist deep underground.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
July 4, 2012

-Watching fireworks this evening? As you're waiting for darkness to arrive, point out the two brightest stars of summer: Vega very high in the east, and Arcturus very high in the southwest.

-Far below Arcturus are Saturn and, just under it, Spica. Off to their right and perhaps a bit lower is orangy little Mars.

-Earth is at aphelion, its farthest from the Sun for the year (just 1/30 farther than at perihelion in January).

Astro Picture of the Day:
July 4, 2012

Source:
What stands between you and the Sun? Apparently, as viewed from Paris last week, one visible thing after another. First, in the foreground, is the Basilica of the Sacred Heart, built in the late 1800s and located on the highest hill in Paris, France. Next, well behind the basilica's towers in the above image, are thin clouds forward scattering sunlight. Finally, far in the distance and slightly buried into the Sun's surface, are sunspots, the most prominent of which is sunspot region AR 1512 visible near the disk center. Since the time that this sunset image was taken, the sunspot region on the far left, AR 1515, has unleashed a powerful solar flare. Although most particles from that flare are expected to miss the Earth, sky enthusiasts are on watch for Sun events that might cause bright auroras in an invisible thing that stands between you and the Sun: the Earth's atmosphere.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
July 5, 2012

-The waning gibbous Moon rises around nightfall. The bright star high above it is Altair. Look a fist-width or more to Altair's left, and perhaps a bit lower, for the little constellation Delphinus, the leaping Dolphin. His nose points left.

-Venus and Jupiter (magnitudes –4.7 and –2.1) shine low in the east-northeast during dawn. They're stacked 5° apart with Jupiter on top, as shown at the top of this page. Watch Aldebaran, much fainter, closing in on Venus from below. In Venus's starry background are the Hyades, while the Pleiades pose above Jupiter. Bring binoculars and look early!

Astro Picture of the Day:
July 5, 2012

Source:
Magnificent spiral galaxy NGC 4565 is viewed edge-on from planet Earth. Also known as the Needle Galaxy for its narrow profile, bright NGC 4565 is a stop on many telescopic tours of the northern sky, in the faint but well-groomed constellation Coma Berenices. This sharp, colorful image reveals the galaxy's bulging central core cut by obscuring dust lanes that lace NGC 4565's thin galactic plane. An assortment of other background galaxies is included in the pretty field of view, with neighboring galaxy NGC 4562 at the upper left. NGC 4565 itself lies about 40 million light-years distant and spans some 100,000 light-years. Easily spotted with small telescopes, sky enthusiasts consider NGC 4565 to be a prominent celestial masterpiece Messier missed.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
July 6, 2012

-After nightfall at this time of year, the W-shaped constellation Cassiopeia has just passed its lowest point in the north and is beginning its long, slow climb in the north-northeast. The later in the night you look, the more altitude it gains. But the farther south you live, the lower it will be.

-Mercury (about magnitude +0.5 and fading) is becoming harder to see very low in the west-northwest about 45 minutes after sundown. Far to its right are fainter Pollux and Castor; use binoculars.

Astro Picture of the Day:
July 6, 2012

Source:
A mere 30 million light-years away, large spiral galaxy NGC 3628 (center left) shares its neighborhood in the local Universe with two other large spirals, in a magnificent grouping otherwise known as the Leo Triplet. In fact, fellow trio member M65 is near the center right edge of this deep cosmic group portrait, with M66 just above it and to the left. But, perhaps most intriguing is the spectacular tail stretching up and to the left for about 300,000 light-years from NGC 3628's warped, edge-on disk. Know as a tidal tail, the structure has been drawn out of the galaxy by gravitational tides during brief but violent past interactions with its large neighbors. Not often imaged so distinctly, the tidal tail is composed of young bluish star clusters and star-forming regions.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
July 7, 2012

-The red long-period variable star R Draconis should be at its maximum brightness of about magnitude 7.6 this week. Binoculars should show it.

-Aldebaran passes 1° to the right or lower right of Venus low in the dawn Sunday through Tuesday mornings.

The dawn sky on July 4th, as captured by Gregg Alliss near Marion, Iowa. He took this 7-second exposure through an 18-mm f/7.1 lens at ISO 800.

Astro Picture of the Day:
July 7, 2012

Source:
Close to the Great Bear (Ursa Major) and surrounded by the stars of the Hunting Dogs (Canes Venatici), this celestial wonder was discovered in 1781 by the metric French astronomer Pierre Mechain. Later, it was added to the catalog of his friend and colleague Charles Messier as M106. Modern deep telescopic views reveal it to be an island universe -- a spiral galaxy around 30 thousand light-years across located only about 21 million light-years beyond the stars of the Milky Way. Along with a bright central core, this colorful composite image highlights youthful blue star clusters and reddish stellar nurseries tracing the galaxy's spiral arms. It also shows off remarkable reddish jets of glowing hydrogen gas. In addition to small companion galaxy NGC 4248 (bottom right) background galaxies can be found scattered throughout the frame. M106 (aka NGC 4258) is a nearby example of the Seyfert class of active galaxies, seen across the spectrum from radio to x-rays. Active galaxies are believed to be powered by matter falling into a massive central black hole.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
July 8, 2012

-After nightfall at this time of year, the W-shaped constellation Cassiopeia has just passed its lowest point in the north and is beginning its long, slow climb in the north-northeast. The later in the night you look, the more altitude it gains. But the farther south you live, the lower it will be.

-Mercury is disappearing deep in the sunset.

Astro Picture of the Day:
July 8, 2012

Source:
Sometimes both heaven and Earth erupt. In Iceland in 1991, the volcano Hekla erupted at the same time that auroras were visible overhead. Hekla, one of the most famous volcanoes in the world, has erupted at least 20 times over the past millennium, sometimes causing great destruction. The last eruption occurred only twelve years ago but caused only minor damage. The green auroral band occurred fortuitously about 100 kilometers above the erupting lava. Is Earth the Solar System's only planet with both auroras and volcanos?

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
July 9, 2012

-At nightfall, spot bright Arcturus very high in the southwest to west. It's way above Saturn, Spica, and Mars. Look off to the right of Arcturus for the Big Dipper — which is hanging down and, as night grows late, previewing its late-summer dip as if scooping water.

Astro Picture of the Day:
July 9, 2012

Source:
What did you do over your winter vacation? If you were the Opportunity rover on Mars, you spent four months of it stationary and perched on the northern slope of Greeley Haven -- and tilted so that your solar panels could absorb as much sunlight as possible. During its winter stopover, the usually rolling robot undertook several science activities including snapping over 800 images of its surroundings, many of which have been combined into this 360-degree digitally-compressed panorama and shown in exaggerated colors to highlight different surface features. Past tracks of Opportunity can be seen toward the left, while Opportunity's dust covered solar panels cross the image bottom. Just below the horizon and right of center, an interior wall of 20-kilometer Endeavour Crater can be seen. Now that the northern Martian winter is over, Opportunity is rolling again, this time straight ahead (north). The rover is set to investigate unusual light-colored soil patches as it begins again to further explore the inside of Endeavour, a crater that may hold some of the oldest features yet visited.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
July 10, 2012

-As the stars begin to come out, look very high in the east for bright Vega. How soon can you spot the other two stars of the Summer Triangle? Deneb is 24° to Vega's lower left: two or three fist-widths at arm's length. Altair is 34° to Vega's lower right: three or four fists.

-Vega passes the zenith around midnight.

-The Sun is displaying a spot group big enough to see without optical aid, just a safe solar filter. Active Region AR 1520 is on the eastern side of the Sun as of Monday and is rotating toward the midline of the Sun's face, where it should be all the more obvious — and could blast some serious solar weather our way if a big flare happens to erupt within it. High-res near-real-time image from SOHO.

Astro Picture of the Day:
July 10, 2012

Source:
Was Devils Tower once an explosive volcano? Famous for its appearance in films such as Close Encounters, the origin of Devil's Tower in Wyoming, USA is still debated, with a leading hypothesis holding that it is a hardened lava plume that probably never reached the surface to become a volcano. The lighter rock that once surrounded the dense volcanic neck has now eroded away, leaving the dramatic tower. High above, the central band of the Milky Way galaxy arches across the sky. Many notable sky objects are visible, including dark strands of the Pipe Nebula and the reddish Lagoon Nebula to the tower's right. Green grass and trees line the moonlit foreground, while clouds appear near the horizon to the tower's left. Unlike many other international landmarks, mountaineers are permitted to climb Devils Tower.