Terry's Astronomy Thread.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
September 16, 2012

-The bright eclipsing variable star Algol is now high in the northeast by 9 or 10 p.m. local daylight-saving time. Algol should be at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 9:51 p.m. Eastern Daylight Time. It takes several additional hours to fade and to rebrighten.

Astro Picture of the Day:
September 16, 2012

Source:
How old are Saturn's rings? No one is quite sure. One possibility is that the rings formed relatively recently in our Solar System's history, perhaps only about 100 million years ago when a moon-sized object broke up near Saturn. Evidence for a young ring age includes a basic stability analysis for rings, and the fact that the rings are so bright and relatively unaffected by numerous small dark meteor impacts. More recent evidence, however, raises the possibility that some of Saturn's rings may be billions of years old and so almost as old as Saturn itself. Inspection of images by the Saturn-orbiting Cassini spacecraft indicates that some of Saturn's ring particles temporarily bunch and collide, effectively recycling ring particles by bringing fresh bright ices to the surface. Seen here, Saturn's rings were imaged in their true colors by the robotic Cassini in late October. Icy bright Tethys, a moon of Saturn likely brightened by a sandblasting rain of ice from sister moon Enceladus, is visible in front of the darker rings.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
September 17, 2012

-As summer prepares to give way to fall (at the equinox on September 22nd), Vega prepares to give way to Deneb as the bright zenith star when night descends. This is also when Altair is crossing its own highest point due south.

Astro Picture of the Day:
September 17, 2012

Source:
What's happened to our Sun? Nothing very unusual -- it just threw a filament. At the end of last month, a long standing solar filament suddenly erupted into space producing an energetic Coronal Mass Ejection (CME). The filament had been held up for days by the Sun's ever changing magnetic field and the timing of the eruption was unexpected. Watched closely by the Sun-orbiting Solar Dynamics Observatory, the resulting explosion shot electrons and ions into the Solar System, some of which arrived at Earth three days later and impacted Earth's magnetosphere, causing visible aurorae. Loops of plasma surrounding an active region can be seen above the erupting filament in the ultraviolet image. If you missed this auroral display please do not despair - over the next two years our Sun will be experiencing a solar maximum of activity which promises to produce more CMEs that induce more Earthly auroras.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
September 18, 2012

-Look very low in the west-southwest in early twilight for the slender crescent Moon. Well to the Moon's right, Saturn is departing for the season, as shown above (for North America).

-Mars and Saturn (magnitudes +1.2 and +0.8) are low in the southwest and west-southwest, respectively, after sunset. They're now about 20° apart. Use binoculars to help find them in early twilight before they sink too low.

Mars begins the week just 1° below Alpha Librae, a wide binocular double star of magnitudes 3 and 5. By Tuesday September 18th, Mars is 2½° left of the star pair.

Astro Picture of the Day:
September 18, 2012

Source:
This shot of the Milky Way's galactic core was taken by one of my friends who went up to Algonquin Park this weekend to shoot the stars, as I went up north to Wasaga Beach to test my new tripod. He did not add any colour, but simply took 15 images via the Astrotrac star tracker he bought and stacked them. The picture was Shot on the Canon 5DMk2 and Zeiss 50mm at f2.8, ISO1600. The yellow glow at the bottom is light pollution from the distant town of Whitney. How many messier objects can you see in this photo? The spout of the Saggitarius Teapot is visible at the bottom left of this image, bordering the Saggitarius Star Cloud.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
September 19, 2012

-Look much closer right of the Moon this evening in twilight for little Mars, as shown below (for North America). The Moon occults (covers) Mars for parts of central and southern South America before sunset.

-More information on the lunar occultation can be found here: http://earthsky.org/tonight/moon-nea...n-september-19

Astro Picture of the Day:
September 19, 2012

Source:
Is it art? Earlier this month, space station astronaut Aki Hoshide (Japan) recorded this striking image while helping to augment the capabilities of the Earth-orbiting International Space Station (ISS). Visible in this outworldly assemblage is the Sun, the Earth, two portions of a robotic arm, an astronaut's spacesuit, the deep darkness of space, and the unusual camera taking the picture. This image joins other historic - and possibly artistic -- self-portraits taken previously in space. The Expedition 32 mission ended yesterday when an attached capsule undocked with the ISS and returned some of the crew to Earth.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
September 19, 2012

-This evening the Moon marks the way to Mars-like Antares, twinkling to its lower left as shown above.

-Antares and Scorpius are already sinking at sunset into the horizon after sunset as the milky way is at its highest point.

Astro Picture of the Day:
September 20, 2012

Source:
An analemma is that figure-8 curve that you get when you mark the position of the Sun at the same time each day throughout planet Earth's year. In this case, 17 individual images taken at 0231 UT on dates between April 2 and September 16 follow half the analemma curve, looking east toward the rising sun and the Caspian sea from the boardwalk in the port city of Baku, Azerbaijan. With the sun nearest the horizon, those dates almost span the period between the 2012 equinoxes on March 20 and September 22. The northern summer Solstice on June 20 corresponds to the top of the figure 8 at the left, when the Sun stood at its northernmost declination. Of course, this year the exposure made on June 6 contained a little something extra. Slightly enhanced, the little black spot on the bright solar disk near the top of the frame is planet Venus, caught in a rare transit during this well-planned sunrise analemma project.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
September 21, 2012

-Since 1844, deep-sky observers have known the open star cluster M11 (off the tail of Aquila) as the Wild Duck Cluster. But where exactly are the ducks?

It is located in the beautiful Scutum star cloud, surrounded by one of the most dense star fields in the sky. Many clusters would be lost in such star studded glory, but M11 stands out clearly. According to Burnham's it was Rev. Wm. Derham of England who first resolved the cluster into stars in 1732. It was Admiral Smyth who noted that the main group of brighter stars resemble "a flight of wild ducks."

Burnham's describes M11 as an "Exceptionally fine galactic star cluster, lying on the north edge of the prominent Scutum Star Cloud, and one of the outstanding objects of its type for telescopes of moderate aperture."

Many of the stars are brighter than 11th magnitude, making for a terrific view in even a 6-inch scope. In smaller instruments or binoculars M11 appears as a hazy spot as bright as a 6th magnitude star and can even be glimpsed as such to the naked eye from a dark location. The first stars to resolve will be those that form a triangular structure - Smyth's wild ducks. A 10-inch scope will reveal at least 500 stars here splashed about in spectacular fashion.

Astro Picture of the Day:
September 21, 2012

Source:
September's equinox arrives tomorrow as the Sun crosses the celestial equator heading south. The event marks the astronomical beginning of spring in the southern hemisphere and autumn in the north. And though the connection is still puzzling, the equinox seasons bring an increase in geomagnetic storms. So as northern nights grow longer, the equinox also heralds the arrival of a good season for aurora hunters. Recorded on September 20, these colorful northern lights were captured with camera and wide-angle lens near the Norwegian Sea coast outside Tromsø in Northern Norway. Shining at altitudes of 100 kilometers or so, the aurora rays are parallel, but perspective makes them appear to radiate from a vanishing point behind the silhouetted pine tree. Stars in this enchanting northern night include Polaris above and right of the tree top, and yellowish giant stars Shedar (Alpha Cassiopiae) to the left and Kochab (Beta Ursae Minoris) to the right. Bright Altair shines through the greenish auroral curtain at the lower left of the scene.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
September 22, 2012

-First-quarter Moon (exact at 3:41 p.m. EDT). The Moon shines in Sagittarius, with the Sagittarius Teapot pattern to its lower left after dusk.

-Sixth-magnitude Uranus is only 1.4 arcminutes from the similarly bright, but differently colored, star 44 Piscium this evening and tomorrow evening. Binoculars and a chart are all you need. They remain close all week.

-The tiny black shadow of Io crosses Jupiter's face from 10:53 p.m. to 1:01 a.m. EDT tonight, followed by Io itself from 12:10 to 2:18 a.m. Eastern Daylight Time. Remember that Jupiter doesn't rise until around 10 or 11 p.m. in your local daylight time.

-Autumn begins in the Northern Hemisphere (spring in the Southern Hemisphere) at the equinox, 10:49 a.m. EDT. This is when the center of the Sun crosses the equator heading south for the year. Today the Sun rises and sets nearly at the east and west points on your horizon.

Astro Picture of the Day:
September 22, 2012

Source:
Today, the Sun crosses the celestial equator heading south at 14:49 Universal Time. An equinox (equal night), this astronomical event marks the first day of autumn in the northern hemisphere and spring in the south. With the Sun on the celestial equator, Earth dwellers will experience nearly 12 hours of daylight and 12 hours of darkness. To celebrate, consider this careful record of the Sun's yearly journey through southern Austrian skies. The scene is composed of images made at the same time each day, capturing the Sun's position on dates from September 29, 2011 through September 9, 2012. The multiple suns trace an intersecting curve known as an analemma. In fact, the past year's two equinox dates correspond to the middle (not the intersection point) of the curve. The summer and winter solstices are at the top and bottom. Of course, many would also consider it a good idea to travel the mountain road toward the left, passing the vineyards along the way to reach the nearby town of Kitzeck and toast the equinox with a glass of wine. Near the roadside bench is a windmill-like klapotetz, traditionally used in this wine-growing region to keep the birds away.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
September 23, 2012

-Jupiter's moon Io reappears from behind Jupiter's eastern limb at 11:39 p.m. Eastern Daylight Time.

-Uranus (magnitude 5.7, at the Pisces-Cetus border) and Neptune (magnitude 7.8, in Aquarius) are well up in the southeast during evening. This week Uranus is very close to the similarly bright, but differently colored, star 44 Piscium. The two appear closest on the American evenings of Saturday and Sunday September 22nd and 23rd, when they're 1.4 arcminutes apart. Visit HERE to see if you can spot them this week, most importantly tonight!

Astro Picture of the Day:
September 23, 2012

Source:
Yesterday was an equinox, a date when day and night are equal. Today, and every day until the next equinox, the night will be longer than the day in Earth's northern hemisphere, and the day will be longer than the night in Earth's southern hemisphere. An equinox occurs midway between the two solstices, when the days and nights are the least equal. The picture is a composite of hourly images taken of the Sun above Bursa, Turkey on key days from solstice to equinox to solstice. The bottom Sun band was taken during the winter solstice in 2007 December, when the Sun could not rise very high in the sky nor stay above the horizon very long. This lack of Sun caused winter. The top Sun band was taken during the summer solstice in 2008 June, when the Sun rose highest in the sky and stayed above the horizon for more than 12 hours. This abundance of Sun caused summer. The middle band was taken during the Vernal Equinox in 2008 March, but it is the same sun band that Earthlings saw yesterday, the day of the Autumnal Equinox.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
September 24, 2012

-Jupiter's moon Europa reappears out of eclipse by Jupiter's shadow just off the planet's western limb at 11:48 p.m. Eastern Daylight Time, and then it slips behind the western limb 13 minutes later.

Astro Picture of the Day:
September 24, 2012

Source:
This shock wave plows through space at over 500,000 kilometers per hour. Moving toward to bottom of this beautifully detailed color composite, the thin, braided filaments are actually long ripples in a sheet of glowing gas seen almost edge on. Cataloged as NGC 2736, its narrow appearance suggests its popular name, the Pencil Nebula. About 5 light-years long and a mere 800 light-years away, the Pencil Nebula is only a small part of the Vela supernova remnant. The Vela remnant itself is around 100 light-years in diameter and is the expanding debris cloud of a star that was seen to explode about 11,000 years ago. Initially, the shock wave was moving at millions of kilometers per hour but has slowed considerably, sweeping up surrounding interstellar gas.

[Bluearrowll]

Re: Terry's Astronomy Thread.

What's in the sky tonight?
September 25, 2012

-The waxing gibbous Moon this evening shines almost midway between 1st-magnitude Altair, very high to its upper right, and 1st-magnitude Fomalhaut, about equally far to the Moon's lower left.

-Mars (magnitude +1.2, in Libra) remains low in the southwest in evening twilight. Don't confuse it with twinklier orange Antares ("Anti-Mars") well to its left or upper left. The gap between them shrinks from 20° to 16° this week.

Astro Picture of the Day:
September 25, 2012

Source:
What surrounds the florid Rosette nebula? To better picture this area of the sky, the famous flowery emission nebula on the far right has been captured recently in a deep and dramatic wide field image that features several other sky highlights. Designated NGC 2237, the center of the Rosette nebula is populated by the bright blue stars of open cluster NGC 2244, whose winds and energetic light are evacuating the nebula's center. Below the famous flower, a symbol of Valentine's Day, is a column of dust and gas that appears like a rose's stem but extends hundreds of light years. Across the above image, the bright blue star just left and below the center is called S Monocerotis. The star is part of the open cluster of stars labelled NGC 2264 and known as the Snowflake cluster. To the right of S Mon is a dark pointy featured called the Cone nebula, a nebula likely shaped by winds flowing out a massive star obscured by dust. To the left of S Mon is the Fox Fur nebula, a tumultuous region created by the rapidly evolving Snowflake cluster. The Rosette region, at about 5,000 light years distant, is about twice as far away as the region surrounding S Mon. The entire field can be seen with a small telescope toward the constellation of the Unicorn (Monoceros).

[darklordsarumon9]

Re: Terry's Astronomy Thread.

Thank you for keeping this wonderful thread going<3

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-Look straight below the Moon, as twilight fades this evening, for Fomalhaut rising. How soon can you see it coming into view? Look way down; they're about 25° apart. The farther south you live, the earlier in twilight you can pick it up.

-Saturn (magnitude +0.8, in Virgo) is sinking away into the sunset far to the lower right of Mars.

Astro Picture of the Day:
September 26, 2012

Source:
It's not every day that a space shuttle lands at LAX. Although this was a first for the major Los Angeles airport hub, it was a last for the space shuttle Endeavour, as it completed its tour of California skies and landed, albeit atop a 747, for the last time. During its last flight the iconic shuttle and its chase planes were photographed near several of California's own icons including the Golden Gate Bridge in San Francisco, the Hollywood Sign, and the skyline of Los Angeles. Previously, in May, the space shuttle Enterprise was captured passing behind several of New York City's icons on its way to the Intrepid Sea, Air, & Space Museum. Pictured above, the piggybacking shuttle was snapped on approach last week to LAX as it crossed above and beyond a major Los Angeles street. Now retired, the space shuttles are all museum pieces, with the above shuttle scheduled to be towed along the streets of LA to the California Science Center.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-With fall here, the bright "Spring Star" Arcturus is moving ever lower in the west after dusk. But it's got a long way to go before disappearing for the year. Look far to its right for the Big Dipper, which is now turning around to lie almost upright.

-Jupiter (magnitude –2.5, in Taurus) rises in the east-northeast around 10 or 11 p.m. daylight saving time. Once it's clear of the horizon, look for fainter orange Aldebaran twinkling 8° to its right and Beta Tauri (Elnath) a trace farther to its left. By the beginning of dawn, this lineup-of-three stands high and diagonal in the south.

Astro Picture of the Day:
September 27, 2012

Source:
Cosmic dust clouds sprawl across a rich field of stars in this sweeping telescopic vista near the northern boundary of Corona Australis, the Southern Crown. Probably less than 500 light-years away and effectively blocking light from more distant, background stars in the Milky Way, the densest part of the dust cloud is about 8 light-years long. At its tip (upper right) is a group of lovely reflection nebulae cataloged as NGC 6726, 6727, 6729, and IC 4812. A characteristic blue color is produced as light from hot stars is reflected by the cosmic dust. The smaller yellowish nebula (NGC 6729) surrounds young variable star R Coronae Australis. Magnificent globular star cluster NGC 6723 is toward the upper right corner of the view. While NGC 6723 appears to be part of the group, it actually lies nearly 30,000 light-years away, far beyond the Corona Australis dust clouds.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-High in the northeast after dark this week, the landmark constellation Cassiopeia is tilting up to stand almost on end. It's shaped like a flattened W. The brighter side of the W is on top.

-Uranus is at opposition tonight.

Astro Picture of the Day:
September 28, 2012

Source:
Bright star Markab anchors this dusty skyscape. At the top right corner of the frame, Markab itself marks a corner of an asterism known as the Great Square, found within the boundaries of the constellation Pegasus, the flying horse. The wide and deep telescopic view rides along for some 5 degrees or about 10 times the angular diameter of the Full Moon, with blue reflection nebulae scattered around the scene. And even though this line-of-sight looks away from the plane of our Milky Way galaxy, it covers a region known to be filled with nearby molecular clouds. The associated dust clouds, high latitude galactic cirrus, are less than 1,000 light-years distant. Still apparent, but far beyond the Milky Way, are background galaxies, like the prominent edge-on spiral NGC 7497 near picture center.

[Bluearrowll]

Re: Terry's Astronomy Thread.

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

-It's Harvest Moon tonight, the full Moon closest to the fall equinox (exactly full at 11:19 p.m. EDT). The Moon shines in dim Pisces this evening, below the Great Square of Pegasus.

-Venus (magnitude –4.1, in Leo) rises in darkness around 4 a.m. daylight saving time (depending on where you live), emerging above the east-northeast horizon two hours before the first glimmer of dawn. By dawn it's blazing high in the east.

-This week Venus is passing Regulus, which is only 1/150 as bright. They're closest on Wednesday morning October 3rd: separated by 0.2° or less before dawn in the Americas. Bring binoculars to help separate them!

Astro Picture of the Day:
September 29, 2012

Source:
Like delicate cosmic petals, these clouds of interstellar dust and gas have blossomed 1,300 light-years away in the fertile star fields of the constellation Cepheus. Sometimes called the Iris Nebula and dutifully cataloged as NGC 7023 this is not the only nebula in the sky to evoke the imagery of flowers. Still, this remarkable image shows off the Iris Nebula's range of colors and symmetries in impressive detail. Within the Iris, dusty nebular material surrounds a hot, young star. The dominant color of the brighter reflection nebula is blue, characteristic of dust grains reflecting starlight. Central filaments of the dusty clouds glow with a faint reddish photoluminesence as some dust grains effectively convert the star's invisible ultraviolet radiation to visible red light. Infrared observations indicate that this nebula may contain complex carbon molecules known as PAHs. The bright blue portion of the Iris Nebula is about six light-years across.