Terry's Astronomy Thread.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-At this time of year, the Big Dipper stands on its handle in the northeast during evening. The top of the Dipper — the two Pointer stars, pointing left to Polaris — are now at exactly Polaris's height around 8 p.m. (depending on where you live in your time zone).

-Mercury is low in the western twilight and rapidly fading: from magnitude +0.8 on February 22nd to +4 on March 1st! Catch it early in the week before it's gone.

-Mars is lost in the glow of sunset, even lower than Mercury.

Astro Picture of the Day:
February 23, 2013

Source:
A meteoroid fell to Earth on February 15, streaking some 20 to 30 kilometers above the city of Chelyabinsk, Russia at 9:20am local time. Initially traveling at about 20 kilometers per second, its explosive deceleration after impact with the lower atmosphere created a flash brighter than the Sun. This picture of the brilliant bolide (and others of its persistent trail) was captured by photographer Marat Ametvaleev, surprised during his morning sunrise session creating panoramic images of the nearby frosty landscape. An estimated 500 kilotons of energy was released by the explosion of the 17 meter wide space rock with a mass of 7,000 to 10,000 tons. Actually expected to occur on average once every 100 years, the magnitude of the Chelyabinsk event is the largest known since the Tunguska impact in 1908.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-After dinnertime at this time of year, four carnivore constellations stand in a row from the northeast to south. They're all seen in profile with their noses pointed up and their feet (if any) to the right: Ursa Major in the northeast (with the Big Dipper as its brightest part), Leo in the east (with the Moon by his forefoot tonight), Hydra the Sea Serpent in the southeast, and Canis Major in the south.

-Telescope users in eastern North America can watch Jupiter's moon Europa reappear out of eclipse from Jupiter's shadow around 6:59 p.m. EST. Then Io reappears out of eclipse around 8:55 p.m. EST. Both events happen just east of the planet.

Astro Picture of the Day:
February 24, 2013

Source:
The Whirlpool Galaxy is a classic spiral galaxy. At only 30 million light years distant and fully 60 thousand light years across, M51, also known as NGC 5194, is one of the brightest and most picturesque galaxies on the sky. The above image is a digital combination of a ground-based image from the 0.9-meter telescope at Kitt Peak National Observatory and a space-based image from the Hubble Space Telescope highlighting sharp features normally too red to be seen. Anyone with a good pair of binoculars, however, can see this Whirlpool toward the constellation of the Hunting Dogs (Canes Venatici. M51 is a spiral galaxy of type Sc and is the dominant member of a whole group of galaxies. Astronomers speculate that M51's spiral structure is primarily due to its gravitational interaction with a smaller galaxy just off the top of the image.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-Full Moon this evening (exactly full at 3:26 p.m. EST). The Moon is south of Leo: in the dim constellation Sextans for part of the night.

-Saturn (magnitude +0.5, in Libra) rises in the east-southeast around 11 p.m. Watch for it to come up well to the lower left of Spica and farther to the lower right of brighter Arcturus. Saturn shines highest in the south before dawn — more or less between Spica to its right and Antares farther to its lower left.

Astro Picture of the Day:
February 25, 2013

Source:
Sometimes the Moon is a busy direction. Last week, for example, our very Moon passed in front of the planet Jupiter. While capturing this unusual spectacle from New South Wales, Australia, a quick-thinking astrophotographer realized that a nearby plane might itself pass in front of the Moon, and so quickly reset his camera to take a continuous series of short duration shots. As hoped, for a brief instant, that airplane, the Moon, and Jupiter were all visible in a single exposure, which is shown above. But the project was not complete - a longer exposure was then taken to bring up three of the Jupiter's own moons: Io, Calisto, and Europa (from left to right). Unfortunately, this triple spectacle soon disappeared. Less than a second later, the plane flew away from the Moon. A few seconds after that, the Moon moved to cover all of Jupiter. A few minutes after that, Jupiter reappeared on the other side of the Moon, and even a few minutes after that the Moon moved completely away from Jupiter. Although hard to catch, planes cross in front of the Moon quite frequently, but the Moon won't eclipse Jupiter again for another three years.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-With spring less than a month away, Orion is starting to tip over toward the southwest fairly early in the evening now.

Astro Picture of the Day:
February 26, 2013

Source:
Does it rain on the Sun? Yes, although what falls is not water but extremely hot plasma. An example occurred in mid-July 2012 after an eruption on the Sun that produced both a Coronal Mass Ejection and a moderate solar flare. What was more unusual, however, was what happened next. Plasma in the nearby solar corona was imaged cooling and falling back, a phenomenon known as coronal rain. Because they are electrically charged, electrons, protons, and ions in the rain were gracefully channeled along existing magnetic loops near the Sun's surface, making the scene appear as a surreal three-dimensional sourceless waterfall. The resulting surprisingly-serene spectacle is shown in ultraviolet light and highlights matter glowing at a temperature of about 50,000 Kelvin. Each second in the above time lapse video takes about 6 minutes in real time, so that the entire coronal rain sequence lasted about 10 hours.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-The seasons are turning; by 8 or 9 p.m. the Big Dipper has climbed as high in the northeast as Cassiopeia has sunk in the northwest.

-Keep an eye out tomorrow for the moon's close encounter with Spica - if you live in the South American regions the moon actully occults Spica.

Astro Picture of the Day:
February 27, 2013

Source:
What kind of clouds are these? Although their cause is presently unknown, such unusual atmospheric structures, as menacing as they might seem, do not appear to be harbingers of meteorological doom. Known informally as Undulatus asperatus clouds, they can be stunning in appearance, unusual in occurrence, are relatively unstudied, and have even been suggested as a new type of cloud. Whereas most low cloud decks are flat bottomed, asperatus clouds appear to have significant vertical structure underneath. Speculation therefore holds that asperatus clouds might be related to lenticular clouds that form near mountains, or mammatus clouds associated with thunderstorms, or perhaps a foehn wind - a type of dry downward wind that flows off mountains. Such a wind called the Canterbury arch streams toward the east coast of New Zealand's South Island. The above image, taken above Hanmer Springs in Canterbury, New Zealand, in 2005, shows great detail partly because sunlight illuminates the undulating clouds from the side.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-Look for Spica very close to the waning gibbous Moon late this evening, as seen from North America. The Moon occults (hides) Spica for viewers from southeastern Mexico through central South America.

Astro Picture of the Day:
February 28, 2013

Source:
The alarmingly tall inhabitants of this small, snowy planet cast long shadows in bright moonlight. Of course, the snowy planet is actually planet Earth and the wide-angle mosaic, shown as a little planet projection, was recorded on February 25 during the long northern night of the Full Snow Moon. The second brightest celestial beacon is Jupiter, on the right above the little planet's horizon. Lights near Östersund, Sweden glow along the horizon, surrounding the snow covered lake Storsjön. The photographer reports that the journey out onto the frozen lake by sled to capture the evocative Full Snow Moon scene was accompanied by ice sounds, biting cold, and a moonlit mist.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-Around 11 p.m. this evening (depending on where you live), the waning Moon rises with Saturn glowing a few degrees to its left, as shown above. The pair remain close for the rest of the night.

-Long awaited, Comet PanSTARRS now looks likely to reach about 2nd magnitude at its best in mid-March, when it will be low in the western evening twilight for Northern Hemisphere observers.

Astro Picture of the Day:
March 1, 2013

Source:
The colors of the solar system's innermost planet are enhanced in this tantalizing view, based on global image data from the Mercury-orbiting MESSENGER spacecraft. Human eyes would not discern the clear color differences but they are real none the less, indicating distinct chemical, mineralogical, and physical regions across the cratered surface. Notable at the upper right, Mercury's large, circular, tan colored feature known as the Caloris basin was created by an impacting comet or asteroid during the solar system's early years. The ancient basin was subsequently flooded with lava from volcanic activity, analogous to the formation of the lunar maria. Color contrasts also make the light blue and white young crater rays, material blasted out by recent impacts, easy to follow as they extend across a darker blue, low reflectance terrain.

[Bluearrowll]

Re: Terry's Astronomy Thread.

Update: Comet PANSTARRS information has been posted in the "Upcoming Events" tab. It becomes visible to the Northern Hemisphere beginning March 7, 2013.

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

-Now that March has begun, Sirius takes over from Orion to stand at its highest in the south soon after dark

News Posted Today:
March 1, 2013:
Mars has Front-Row Seat for 2014 Comet


Astro Picture of the Day:
March 2, 2013

Source:
Each day on planet Earth can have a serene beginning at sunrise as the sky gently grows bright over a golden eastern horizon. This sunrise panorama seems to show such a moment on the winter morning of February 15. In the mist, a calm, mirror-like stretch of the Miass River flows through the foreground along a frosty landscape near Chelyabinsk, Russia. But the long cloud wafting through the blue sky above is the evolving persistent train of the Chelyabinsk Meteor. The vapor trail was left by the space rock that exploded over the city only 18 minutes earlier, causing extensive damage and injuring over 1,000 people. A well-documented event, the numerous webcam and dashcam video captures from the region soon contributed to a reconstruction of the meteor's trajectory and an initial orbit determination. Preliminary findings indicate the parent meteoriod belonged to the Apollo class of Earth crossing asteroids.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-Jupiter's moon Europa disappears into eclipse by Jupiter's shadow around 7:10 p.m. EST, after reappearing from behind Jupiter's eastern limb just 14 minutes earlier. Io disappears behind Jupiter's other side 10 minutes later. Europa then reappears out of eclipse at 9:38 p.m. EST, followed by Io at 10:50 p.m. EST.

Astro Picture of the Day:
March 3, 2013

Source:
One of the natural wonders of planet Earth, the Grand Canyon in the American southwest stretches across this early evening skyscape. The digitally stacked sequence reveals the canyon's layers of sedimentary rock in bright moonlight. Exposed sedimentary rock layers range in age from about 200 million to 2 billion years old, a window to history on a geological timescale. A recent study has found evidence that the canyon itself may have been carved by erosion as much as 70 million years ago. With the camera fixed to a tripod while Earth rotates, each star above carves a graceful arc through the night sky. The concentric arcs are centered on the north celestial pole, the extension of Earth's rotation axis into space, presently near the bright star Polaris.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-With Sirius on the meridian after dinnertime, so is the Winter Triangle — since Sirius is its bottom corner. The other two are Procyon to its upper left and Betelgeuse to its upper right. The Winter Triangle is almost perfectly equilateral: all three stars are 26° from each other within about 1° accuracy.

-Last-quarter Moon (exact at 4:53 p.m. EST).

Astro Picture of the Day:
March 4, 2013

Source:
Sprawling across almost 200 light-years, emission nebula IC 1805 is a mix of glowing interstellar gas and dark dust clouds. Derived from its Valentine's-Day-approved shape, its nickname is the Heart Nebula. About 7,500 light-years away in the Perseus spiral arm of our galaxy, stars were born in IC 1805. In fact, near the cosmic heart's center are the massive hot stars of a newborn star cluster also known as Melotte 15, about 1.5 million years young. A little ironically, the Heart Nebula is located in the constellation of the mythical Queen of Aethiopia (Cassiopeia). This deep view of the region around the Heart Nebula spans about two degrees on the sky or about four times the diameter of the Full Moon.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-On the traditional divide between the winter and spring sky is the dim constellation Cancer. It's between Gemini to its west and Leo to its east. Cancer has a unique feature: the Beehive Star Cluster, M44, in its middle. The Beehive shows to the naked eye only if your light pollution is slight. Look for it a little less than halfway from Pollux to Regulus. With binoculars it's a snap.

Astro Picture of the Day:
March 5, 2013

Source:
Two impressive comets will both reach their peak brightness during the next two weeks. Taking advantage of a rare imaging opportunity, both of these comets were captured in the sky together last week over the Atacama desert in South America. Comet C/2012 F6 (Lemmon), visible on the upper left of the above image, is sporting a long tail dominated by glowing green ions. Comet C/2011 L4 (PanSTARRS), visible near the horizon on the lower right, is showing a bright tail dominated by dust reflecting sunlight. The tails of both comets point approximately toward the recently set Sun. Comet Lemmon will be just barely visible to the unaided eye before sunset in southern skies for the next week, and then best viewed with binoculars as it fades and moves slowly north. Comet PanSTARRS, however, will remain visible in southern skies for only a few more days, after which it will remain bright enough to be locatable with the unaided eye as it moves into northern skies. To find the giant melting snowball PanSTARRS, sky enthusiasts should look toward the western horizon just after sunset. Deep sky observers are also monitoring the brightening of Comet C/2012 S1 (ISON), which may become one of the brightest objects in the entire night sky toward the end of 2013.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
March 6, 2013

-Mercury, Venus, and Mars are hidden in the glare of the Sun.

-Jupiter (bright at magnitude –2.3, in Taurus) comes into view high in the south-southwest after sunset and dominates the southwest to west later in the evening. Left of Jupiter is orange Aldebaran; farther to its lower right are the Pleiades. They all set in the west-northwest around midnight or 1 a.m.

In a telescope, Jupiter is shrinking as Earth pulls farther ahead of it in our faster orbit around the Sun. This week it shrinks from 39 to 38 arcseconds wide.

Astro Picture of the Day:
March 6, 2013

Source:
Bright clusters and nebulae abound in the ancient northern constellation of Auriga. The region includes the open star cluster M38, emission nebula IC 410 with Tadpoles, Auriga's own Flaming Star Nebula IC 405, and this interesting pair IC 417 (lower left) and NGC 1931. An imaginative eye toward the expansive IC 417 and diminutive NGC 1931 suggests a cosmic spider and fly. About 10,000 light-years distant, both represent young, open star clusters formed in interstellar clouds and still embedded in glowing hydrogen gas. For scale, the more compact NGC 1931 is about 10 light-years across.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
March 7, 2013

-Comet PANSTARRS now makes its way to the northern hemisphere - however depending on your location it will be difficult to spot today and tomorrow.

-Look west after sunset near the horizon. Binoculars may be needed to pick Comet PanSTARRS out of the bright sky. Look too early and the sky will be too bright; too late and the comet will be too low. On the altitude scale at left, 10° is about the width of your fist held at arm's length.

-This diagram is drawn for a viewer near 40° north latitude (Denver, New York, Madrid) 30 minutes after sunset. If you're south of there, the comet will be a little higher above your horizon early in the month than shown here. North of 40°, it will be a little lower early in March than shown here.

-Algol in Perseus should be at minimum light, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 9:58 p.m. Eastern Standard Time. Algol takes several additional hours to fade and to rebrighten.

Astro Picture of the Day:
March 7, 2013

Source:
Fomalhaut (sounds like "foam-a-lot") is a bright, young, star, a short 25 light-years from planet Earth in the direction of the constellation Piscis Austrinus. In this sharp composite from the Hubble Space Telescope, Fomalhaut's surrounding ring of dusty debris is imaged in detail, with overwhelming glare from the star masked by an occulting disk in the camera's coronagraph. Astronomers now identify, the tiny point of light in the small box at the right as a planet about 3 times the mass of Jupiter orbiting 10.7 billion miles from the star (almost 23 times the Sun-Jupiter distance). Designated Fomalhaut b, the massive planet probably shapes and maintains the ring's relatively sharp inner edge, while the ring itself is likely a larger, younger analog of our own Kuiper Belt - the solar system's outer reservoir of icy bodies. The Hubble data represent the first visible-light image of a planet circling another star.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
March 8, 2013

-Comet PANSTARRS now makes its way to the northern hemisphere - however depending on your location it will be difficult to spot today and tomorrow.

-Look west after sunset near the horizon. Binoculars may be needed to pick Comet PanSTARRS out of the bright sky. Look too early and the sky will be too bright; too late and the comet will be too low. On the altitude scale at left, 10° is about the width of your fist held at arm's length.

-This diagram is drawn for a viewer near 40° north latitude (Denver, New York, Madrid) 30 minutes after sunset. If you're south of there, the comet will be a little higher above your horizon early in the month than shown here. North of 40°, it will be a little lower early in March than shown here.

-Jupiter is 5° from Aldebaran high in the west after dark. But it's now passing only 2° from fainter (3.5-magnitude) Epsilon Tauri, the other tip of the Hyades V pattern, located almost between them.

News Posted Today:
March 7, 2013
Crab Nebula Flares Mysteriously


Astro Picture of the Day:
March 8, 2013

Source:
Want to use a cluster of galaxies as a telescope? It's easier than you might think as distant galaxy clusters naturally act as strong gravitional lenses. In accordance with Einstein's theory of general relativity, the cluster gravitational mass, dominated by dark matter, bends light and creates magnified, distorted images of even more distant background galaxies. This sharp infrared Hubble image illustrates the case for galaxy cluster Abell 68 as a gravitational telescope, explored by amateur astronomer Nick Rose during the ESA-Hubble Hidden Treasures image processing competition. Labels 1 and 2 show two lensed images of the same background galaxy. The distorted galaxy image labeled 2 resembles a vintage space invader! Label 3 marks a cluster member galaxy, not gravitationally lensed, stripped of its own gas as it plows through the denser intergalactic medium. Label 4 includes many background galaxies imaged as elongated streaks and arcs. Abell 68 itself is some 2.1 billion light-years distant toward the constellation Vulpecula. The central region of the cluster covered in the Hubble view spans over 1.2 million light-years.

[darklordsarumon9]

Re: Terry's Astronomy Thread.

Wow, Lemmon and PANSTARRS in the same beautiful picture.

Amazing.