Skywatch Line for Friday, December 11, through Sunday, December 13

This is Dudley Observatory’s Skywatch Line for Friday, December 11, through Sunday, December 13, written by Alan French.

With the Moon reaching new early Friday, the weekend will be dark and moonless. A young crescent Moon, however, will make a brief return to Sunday evening’s sky as darkness falls.

On Sunday at 5:00 pm look for the slender Moon just over 15 degrees above the southwestern horizon. As the Sun moves farther below the horizon the southwestern sky will darken and the Moon will move lower, but the Moon will not set until 6:54 pm.

If you were standing on the Moon a bright, nearly full Earth would be a lovely sight in your skies. Sunlight reflected from Earth shines on the entire visible face of the Moon, brightening the large area experiencing night there. This allows you to see the entire Moon – a bright crescent with the rest of the lunar surface aglow with Earthshine. It is a lovely sight, and with the right foreground could be the subject of a great photograph. Vary your exposures to get one with just the right balance between the crescent and the rest of the Moon. Too long an exposure and the crescent will be overly bright and details will vanish. Too short an exposure and the Earthshine will not show well. (Don’t forget a tripod to keep the camera steady during the relatively long exposures.)

The absence of the Moon is good news for sky watchers – this weekend starts the peak of the annual Geminid meteor shower. The shower will be at its peak on the night of Sunday, December 13 and morning of Monday, December 14, and night of December 14 and morning of Tuesday, December 15. The Geminids rivals the Perseids of August as the best and most reliable meteor shower of the year.

The weather is certainly more agreeable for the August Perseids, but there are no biting insects to provide a distraction in December. Just be sure to dress extra warmly so you won’t get chilled. Since you won’t be active you’ll need more layers than you need when outside for normal winter activities.

If you trace the path of the shower’s meteors backwards, they will all intersect in the constellation Gemini at what is called the “radiant.” As darkness falls, the radiant will be low and few meteors will be seen. If you do see one then it will likely be a long one. As the radiant rises higher, more meteors will be visible, and by about 10 pm the show should be in full swing.

The best views will be from dark skies away from city lights. A reclining lawn chair is ideal for meteor watching. Look high in the sky but facing toward the radiant, which is not far from the star Castor, in Gemini. It is high toward the east at 11 pm and was low in the north northeast early in the evening.

Skywatch Line for Wednesday, December 9th and Thursday, December 10th

This is the Dudley Observatory Skywatch Line for Wednesday, December 9th and Thursday, December 10th written by Louis Suarato

The 3% illuminated, waning crescent Moon sets at 3:15 Wednesday afternoon, and will reappear as a 1% illuminated, razor thin crescent Moon at 5:54 Thursday morning. Saturn rises 15 minutes later, but both will be a challenge to see. The New Moon occurs at 5:29 a.m. Friday.

The Big Dipper asterism in the constellation Ursa Major is parallel to, and low on the northern horizon after Wednesday’s sunset. Throughout the night, the Dipper will climb up the sky, as if scooping up a sea of stars. By midnight, the Big Dipper will be tipped straight up on its handle, perpendicular to the northeastern horizon. As the Big Dipper is rising in the sky, the brightest star in the sky, Sirius moves from east to south. To the east of Sirius, a line of no fewer than 20 open clusters escort Canis Major’s brightest star. The open clusters range from NGC 2301 and 2232 in Monoceros, the constellation to the upper left of Sirius, to M93 and NGC 2527 in the constellation Puppis, to the lower left of Sirius. Another open star cluster, M41, is four degrees below Sirius. M41 was discovered by Giovanni Batista Hodierna before 1654. M41 contains approximately 100 stars and is the size of the full Moon. This open star cluster is estimated to be about 190 million years old and is 2,300 light-years away. According to Robert Burnham, Jr., “M41 is a beautiful object in low power instruments…There is a bright reddish star near the center; many of other stars seem to be arranged in curving rows or groups..”.

You’ll have to stay up late, and into the early morning hours, to see the naked eye visible planets. Jupiter is first, as it clears the eastern horizon around midnight. Jupiter’s moon, Europa, begins its transit at 15 minutes past midnight, followed by its shadow 19 minutes later. The Great Red Spot transits 2 minutes after Europa’s shadow. Mars appears at 2 a.m. in the constellation Virgo, followed by Venus an hour and 40 minutes later. Comet C/2013 US10 Catalina is now to Venus’ upper left, less than a degree from Virgo’s star, Syrma.

Skywatch Line for Monday and Tuesday, December 7th and 8th

This is the Dudley Observatory Skywatch Line for Monday and Tuesday, December seventh and eighth written by Joe Slomka.

The Sun sets at 4:21 PM; night falls at 6:03. Dawn breaks at 5:31 and ends with the Sun rising at 7:13.

The early evening sky holds no bright planets. Nightfall reveals Neptune, Uranus and the asteroid 4Vesta. Neptune still resides in Aquarius; it sets at 8:52 PM.  Pisces still contains Uranus, which is best observed at 7:52 PM. Both gas giants appear blue-green; they require detailed star charts from astronomy magazines, websites and apps. Asteroid 4Vesta hangs out about one-and-a-half degrees from the star Iota, in Cetus. Tiny Vesta also requires a detailed star chart and is best detected at 7:02 PM.

We have been following the continuing planetary parade for the past few months. Bright Jupiter rises first a bit before Midnight. By Astronomical Dawn, it is quite high in Leo, by the lion’s rear leg. On Tuesday morning, the Jovian moon Europa disappears into Jupiter’s shadow at 3:36 AM; at 4:17 AM also Tuesday, the moon Callisto’s shadow begins to march across the planet’s face.

Dawn finds Mars, in Virgo, about 23 degrees below Jupiter; Mars rose about 2 AM. Mars shines at 1.5 magnitude, much dimmer than Jupiter; but, its distinctive rust color gives it away. It appears between Virgo’s bright stars Porrima and Spica. A telescope shows Mars to be about 93 percent illuminated.

Blazing Venus rises, also in Virgo, at 3:34 AM near the star Kappa. It is easily identified about eighteen-and-a-half degrees below Mars. Under moderate powers, Venus appears about ninety percent illuminated.

Venus serves as a guide to Comet Catalina. Catalina shines at magnitude 4.8. It is about five degrees east of Venus.  Both may fit within a wide view telescope or binoculars. As previously mentioned, Catalina is slowly climbing higher daily.

The twenty-seven-day-old Moon shines about eight degrees below Venus. In Libra, it shines at magnitude minus 4.9, but is only 8.5 percent illuminated. Wednesday finds it lower in Libra and only minus 2.5 magnitude and four percent illuminated.

Every history student knows that December 7th marks the anniversary of the Japanese attack on Pearl Harbor. Few people are aware of the date’s astronomical significance. The Japanese high command chose that date because the eighteen-day-old Moon rose before midnight and shone at 87 percent, permitting attack planes to launch and fly to their targets. However, the Moon almost helped foil the surprise raid. The Condor, an American minesweeper, spotted a submarine periscope silhouetted against the moonlight. The Condor called the Ward, a destroyer, who attacked a second submarine and radioed the incident to headquarters. That report was not heeded. Had that information been acted upon, the American fleet would have had at least an hour and a half to prepare.

Skywatch Line for Friday, December 4, through Sunday, December 6

This is Dudley Observatory’s Skywatch Line for Friday, December 4, through Sunday, December 6, written by Alan French.

Reaching last quarter early Thursday, a waning crescent Moon will rise after midnight this weekend, leaving much of the night moonless and dark. The Moon rises at 1:20 am Saturday, 2:17 am Sunday, and 3:14 am Monday.

We’re in a time of transition, moving from the stars of summer toward the winter skies. You can get a preview of the stars of winter, low toward the east to east southeast, by 9:30 pm, and this will likely be offered under much more moderate temperatures.

First look for a very bright star low toward the south southeast, just seven degrees above the horizon. This is Sirius, the Dog Star. It is the brightest star in the night sky and lies only 8.7 light years away. Sirius makes its home in the constellation Canis Major, the Big Dog.

East of Sirius and higher in the sky is Procyon, the luminary of Canis Minor, the Little Dog. It is also bright largely because it is a nearby neighbor, lying 11.4 light years from us.

Moving farther left or northward along the horizon and looking higher still you should spot a pair of star of very similar brightness. The lowest is Pollux, and the upper is Castor, and they mark the heads of the Gemini twins. Pollux, lying at 33.8 light years distance, is closer than Castor at 50.9 light years.

Well above and perhaps a bit right of Castor and Pollux you’ll find bright Capella, which we wrote about last week. To its right and lower in the sky look for the bright reddish star Aldebaran. This is the brightest star in Taurus, the Bull, and marks his eye. If you have found the right star, you should see that it is the top of the lower half of a “V” of stars, lying on its side  and open top to the left. Aldebaran is almost 70 light years away.

Below Aldebaran you should easily spot the distinctive and bright star pattern of Orion, the Hunter, one of the most recognizable constellations in the night sky. The three stars of Orion’s belt are vertical in the sky, with the two stars marking his shoulder to their upper left. Brighter, reddish Betelgeuse marks the hunter’s right shoulder. Now look below and right of the belt to two stars mark Orion’s knees. The brightest, marking his left knee, is Rigel.

Compared to the other stars we’ve visited, Orion’s luminaries are distant neighbors and must be intrinsically bright stars. Rigel lies at a distance of 860 light years and Betelgeuse is 500 light years away. As we look at stars farther way from our Earth, our measurements of distance grow more uncertain.

Revisit our winter stars regularly. They rise four minutes earlier each night. That may not seem like much, but it amounts to two hours in a month, so our winter friends will rapidly move higher in the evening sky as the nights pass. In two months they will be due south at 9:30 pm.

Skywatch Line for Wednesday, December 2nd and Thursday, December 3rd

This is the Dudley Observatory Skywatch Line for Wednesday, December 2nd and Thursday, December 3rd written by Louis Suarato

On December 2, 1995, NASA launched the Solar and Heliospheric Observatory, better known as SOHO. The development of SOHO was brought about by an international collaboration between NASA and the European Space Agency, or ESA. SOHO was designed to provide data from the Sun’s deep core to outer corona and solar wind. In addition to providing spectacular images and videos of sunspots, filaments, prominences, and coronal mass ejections for the last 20 years, SOHO has revolutionized the ability to forecast space weather, providing up to a three day warning of Earth-directed disturbances, and playing a lead role in the early warning system for systems and instruments that may be affected by space weather.

Sunset occurs at 4:22 p.m. Wednesday, providing 9 hours and 16 minutes and 4 seconds of sunlight for the day. Although this weekend will have the earliest sunset of the year at 4:21 p.m., the shortest amount of daylight will occur on December 21st and 22nd at 9 hours and 2 minutes and 36 seconds.

By 6 p.m., the constellation Taurus, with its brightest star, Aldebaran, and Pleiades and Hyades star clusters, is already above the eastern Horizon. Taurus is followed by Orion, which can be viewed in full after 8 p.m., with its brightest stars Betelgeuse and Rigel, and great Orion nebula at the middle of its sword hanging from the Hunter’s belt.

Jupiter rises about 20 minutes after midnight in the constellation Virgo, just 3 degrees above the Last Quarter Moon, which occurs at 2:41 a.m. Thursday. The Moon sets at 12:14 Thursday afternoon. Friday, before dawn, the 30% illuminated, waning crescent Moon and Jupiter will be within 2 degrees. Binoculars or a small telescope should capture both the Moon and Jupiter in the same field of view. It also may be a good opportunity to view Jupiter during daylight hours, using the Moon to find the planet. Mars rises at a few minutes after 2 a.m., followed by Venus an hour and half later. Look about 8 degrees to the lower left of Venus for Comet C/2013 US10 Catalina. Recent reports indicated Comet Catalina is now displaying two tails. Estimates for the comet’s current magnitude range from 7.6 to 6.

Skywatch Line for Monday and Tuesday, November 30th and December 1st

This is the Dudley Observatory Skywatch Line for Monday and Tuesday, November 30th and December 1st written by Joe Slomka.

The Sun sets at 4:23 PM; night falls at 6:03. Dawn begins at 5:25 AM and ends with the Sun rising at 7:05.

There are no bright planets in early twilight sky. Nightfall reveals two outer planets and one asteroid. Neptune is the first to rise in Aquarius.  It appears as a tiny two-second blue dot with a brightness of magnitude 8. Uranus, in Pisces, is brighter at magnitude 5.8 also appears blue. Asteroid 4Vesta is situated about two degrees from the star Iota Ceti. All three require detailed finder charts from astronomy magazines, websites or apps. Neptune sets at 11:19 PM, Vesta at 1:01 AM and Uranus at 2:44 AM.

By 10 PM Monday, the twenty-day-old Moon, which rose at 9:27 PM, shines in Cancer. At magnitude minus 10.6, its brilliance blocks out the beautiful Beehive Star Cluster and its companion M 67. Both are best seen through binoculars, since telescopes magnify them too much. Tuesday the Moon migrates into Leo and parks itself near the bright star Regulus. The Moon remains up the rest of the night.

For a while, we have been watching the parade of bright planets in the dawn sky. Jupiter rises first after Midnight and, by Dawn, is perfectly placed for observation. Telescopic observers can see the Great Red Spot, a giant storm in Jupiter’s atmosphere, at 4:09 AM.

Mars rises next, in Virgo, about twenty degrees below Jupiter. It outshines the nearby star Porrima; Mars is 1.5 magnitude, while Porrima is a dimmer 3.5. Venus is the last planet to rise, also in Virgo and about fourteen degrees beneath Mars. Venus’ minus 4.2 magnitude outshines nearby Spica, which is only first magnitude. In binoculars or telescope, Venus exhibits a crescent illuminated at 67 percent.

The Dawn sky also hosts a visitor – Comet Catalina. Catalina is one of two Arizona telescopes commissioned by Congress to hunt for asteroids that may threaten Earth. As part of its duties, it also captures comets. This comet, officially named C/2013 US10, was discovered two years ago on Halloween. Now the comet is close enough for amateurs to see. It appears about one-and-a-half degrees from the star Kappa Virginis and about ten-and-half degrees below Venus. Tuesday finds it about eleven degrees above the eastern horizon and shines at magnitude 4.7, easily within binocular range. During the next few months, the comet will steadily climb higher and, by New Year’s, will be next to the bright star Arcturus. The comet passed behind the Sun and is on its way out of the Solar System, never to return.

Comets are leftovers from Solar System formation. They reside in the Kuiper Belt, beyond Pluto, and the further Oort Cloud. Comets are mostly ice, with some dirt mixed in. Most stay in those distant regions. However, a comet may receive a gravitational bump and head into the inner Solar System. There are three basic orbits. Some revisit every few years, for example Halley’s Comet; some come too close to the Sun and evaporate away, like 2013’s Comet Ison. A third type arrives and never returns; this is the fate of Comet Catalina.

Skywatch Line for Friday, November 27, through Sunday, November 29

This is Dudley Observatory’s Skywatch Line for Friday, November 27, through Sunday, November 29, written by Alan French.

Having reached full last Wednesday, a bright waning gibbous Moon will rise early in the evening this weekend. Moonrise is at 6:28 pm Friday, 7:27 pm Saturday, and 8:27 pm Sunday. The Sun will be setting around 4:24 pm and the last vestiges of twilight will not vanish until just after 6:00 pm, so there will be only a short window between full darkness and moonrise.

If you look toward the northeast around 6:30 pm you’ll easily spot a very bright star. This is Capella, the brightest star in Auriga, the Charioteer. In older star charts, which often depicted the mythological figures represented by the constellations, this star marked the left shoulder of the Charioteer.

While it may be difficult to picture a charioteer made up of the stars of Auriga, it’s not hard to find the main stars in this conspicuous constellation. Anchored by and including Capella, they form a rough pentagon stretching downward and right. The Charioteer was responsible for the king’s livestock, and the lovely atlases of long ago often depicted him carrying a goat and kids.

The name Capella means “little she-goat.” A small triangle of stars to the right of Capella is known as “the Kids,” representing the young goats.

Capella is the sixth brightest star in the night sky and is just slightly fainter than Vega, which we found high in the sky in the summer. You can still spot Vega in the early evening sky, fairly high toward the north northwest in the early evening, and low in the northwest by 9:30 pm. Like Vega, Capella shines brightly in our skies because it is one of our nearer neighbors, lying at a distance of 42 light years. The light you see tonight left the star in 1973.

Swedish astronomer, physicist, and mathematician Anders Celsius was born on November 27, 1701. He is best known for the Celsius temperature scale. In astronomy he used colored glass plates in the first attempt to make actual measurements of the brightness of stars. All previous estimates were done by eye.

On November 28, 1961, North American Aviation was awarded the contract to design and build the Apollo spacecraft. The first manned Apollo mission blasted off less than 7 years later, on October 11, 1968 and man landed on the Moon on July 20, 1969, and Neil Armstrong and Buzz Aldrin became to the first humans to set foot on the Moon.

Amazingly, the Lunar Reconnaissance Orbiter, or LRO, has taken photographs of the various Apollo landing sites so detailed that they show evidence of our visits. The LRO’s view of the Apollo 11 landing site shows the base of the lunar module and two experiments left on the lunar surface.

Skywatch Line for Wednesday, November 25th and Thursday, November 26th

This is the Dudley Observatory Skywatch Line for Wednesday, November 25th and Thursday, November 26th written by Louis Suarato

The Full Beaver Moon rises in the constellation Taurus at 4:24 p.m. Wednesday, and will reach 100% illumination at 5:45 p.m..  The bright star to the upper right of the Moon is Aldebaran, Taurus’ brightest. Aldebaran, or Alpha Tauri, is an orange giant star with a diameter 44.2 times that of our Sun. Aldebaran is 65 light-years from Earth and is occasionally occulted by the Moon. Thursday morning, Aldebaran will be less than a degree from the Moon as seen from our region in the pre-dawn sky, and will be occulted by the Moon around 5:38 a.m. EST, and should reappear about an hour later. Use binoculars or a small telescope to see this occultation. Aldebaran, Spica and Regulus are the three first magnitude stars that are occulted by the Moon, since they reside within 5 1/2 degrees of the ecliptic, the plane of the Earth’s orbit.

The pre-dawn sky is till filled with planets as Jupiter, Mars and Venus form a line of about 40 degrees. The star 2 degrees to the left of Mars, is Porrima, a double star in the constellation Virgo. Virgo’s brightest star, Spica, can be seen 5 degrees to the lower right of Venus. A Thanksgiving Day challenge will be to see Comet C/2013 US10 (Catalina) approximately 15 degrees to the lower left of Venus. Comet Catalina, now shining at magnitude 4.7, will be easier to see in the coming weeks as it climbs higher on the horizon. Put a reminder on your calendar for the morning of December 7th, as Comet Catalina will be 5 degrees to the left of Venus, and both will be below the 14% illuminated, waning crescent Moon.

C/2013 US10 Catalina is an Oort cloud comet discovered by the Catalina Sky Survey on October 31, 2013. The trajectory for this comet indicates that it will be ejected from our solar system and will not return. Traveling at a speed of 103,000 miles per hour, Comet Catalina reached perihelion on November 15, 2015. Comet C/2013 US10 Catalina will be closest to the Earth on January 12th, when it can be seen near the star Mizar in the Big Dipper’s handle.

Skywatch Line for Monday and Tuesday, November 23rd and 24th

This is the Dudley Observatory Skywatch Line for Monday and Tuesday, November 23rd and 24th written by Joe Slomka.

The Sun sets at 4:26 PM; night falls at 6:06. Dawn begins at 5:18 and ends with the Sun rising at 6:58.

As the sky darkens, only one bright object is seen – the Moon. The twelve-day-old Moon rises in the afternoon and appears about 94 percent illuminated. It borders Pisces and Taurus. Tuesday’s Moon appears fatter and rises about 4 PM. The Moon is due South between eleven and twelve PM on both nights. The Moon sets between five and six AM.

The night sky also contains outer planets Neptune and Uranus, along with asteroid 4Vesta. Neptune is located in Aquarius; Uranus is in Pisces. Vesta lies about two-and-a-half degrees from the star Iota Ceti. The almost “full Moon” is bright enough to make observations of these Solar System members difficult. Neptune sets at 11:47 PM, 4Vesta at 1:24 AM, and Uranus at 3:12 AM.

The famous variable star Algol, in Perseus, dims for about two hours centered on 12:15 AM Wednesday. All night observers can witness the star fade from second to third magnitude.

Pre-dawn skies continue the planetary parade. Bright Jupiter rises first near Leo’s hind leg at 12:48 AM. By 3 AM, it is high enough for observation. On Tuesday at 3:39 AM, sky watchers can see Jupiter’s moon Europa reappear from behind its planet. Wednesday, at 3:22 AM, astronomers can see the Great Red Spot, a giant storm, on Jupiter.

Mars rises, in Virgo, at 2:13 AM. Mars appears much dimmer than Jupiter. However, it brightens a little this month. The Red planet appears about sixteen degrees below Jupiter. Venus is the last to rise, at 3:06 AM, and lies about 11 degrees below Mars. Venus, at minus 4.2 magnitude, is second only to the setting Moon in brilliance. By Dawn, all three are in ideal heights for observation.

Followers of the Skywatch Line know that the Milky Way, which tonight stretches from horizon to horizon, represents the rim of our galaxy. They also know that the faint glow in Andromeda is that of a giant galaxy, similar to ours. However, these “island universes” are not isolated from each other. Their gravitational fields clump galaxies into groups. The Local Group is made of our Milky Way, Andromeda, M 33 in Triangulum, and about a dozen other galaxies. This group is traveling together through space. Some galaxies also interact with each other. A prime example is M 51, off the Big Dipper’s Handle. A telescope shows one galaxy stealing material from another. Some astronomers think that giant galaxies like our own grow by absorbing smaller ones. Colliding galaxies are common telescope sights. It is thought that two spiral galaxies will merge to form an elliptical galaxy. In about three billion years, Andromeda and the Milky Way will probably collide and merge. The result will be a giant galaxy marked by very active star formation.

Skywatch Line for Friday, November 20, through Sunday, November 22

This is Dudley Observatory’s Skywatch Line for Friday, November 20, through Sunday, November 22, written by Alan French.

Reaching first quarter last Thursday, a waxing gibbous Moon will dominate much of the night sky over the weekend. The Moon sets at 1:29 am Saturday, 2:41 am Sunday, and not until 3:53 am Monday. Full moon occurs next Wednesday.

If you have a friend or family member with an interest in amateur astronomy, there are two books I can strongly recommend. “Nightwatch,” by Terence Dickinson, is an excellent introduction to amateur astronomy and telescopes, and includes star charts of some brighter celestial objects that are easy to find. “The Backyard Astronomer’s Guide,” by Dickinson and Alan Dyer, goes into more depth, but does not include star charts. At least one of these books is a must read before investing in a telescope. Without a little background it’s easy to buy a $250 disappointment!

If you’re up early, you’ll have two fine chances to catch the ISS (International Space Station) this weekend. At its highest the station appears brighter than any star, so it is easy to spot gliding through the stars. I will give most times in hours, minutes, and seconds. (The ISS will remain in the morning sky all this month.)

On Sunday morning the ISS will appear at 5:54:23 am, emerging from the Earth’s shadow and into sunlight when it is 18 degrees above the west northwestern horizon. It will then move through the pentagon of stars outlining Auriga, the Charioteer, and reach its highest point, 64 degrees above the southwestern horizon at 5:56:36 am. Its path will take it near Castor, and, especially, Pollux, the brightest stars in Gemini, the twins.

The ISS will then move down toward the southeastern horizon, where it will disappear just before 6:00 am. It will journey past Regulus, in Leo, Jupiter, Mars, and Venus.

Monday morning’s pass is especially interesting with the space station emerging from the Earth’s shadow and brightening into view when already high in the sky. The ISS will appear at 5:03:24 when 67 degrees above the northeastern horizon. Fortunately, its appearance will be near a well-known landmark – it will first appear just below the Big Dipper’s bowl.

It will then move down toward the east southeastern horizon, passing east of brilliant Venus. It will vanish below the horizon at 5:06:30 am.

If you have taken any time exposures of the night sky with a camera, it might be fun to try catching the space station as it emerges from the Earth’s shadow below the Big Dipper’s bowl.