|Skywatch January 2013
(newest at top)
Skywatch Line scripts are written by members of the Albany Area Amateur Astronomers. They can be heard by calling 518-382-7584.
While Mars, Venus and Mercury are lost in the glare of the Sun, Jupiter and Saturn remain visible in the night sky. At 9 P.M. EST, Jupiter can be found approximately 60 degrees high in the southwest in the constellation Taurus between the bright, red giant star, Aldebaran and the Pleiades open star cluster. Saturn rises 40 minutes after midnight between the constellations Virgo and Libra. On Wednesday, January 30th, Jupiter appears stationary against background stars as it ends its retrograde motion (westward) and begins to travel eastward. Earth’s perspective of Jupiter, or any superior planet (planets outside the solar orbit of Earth), changes as Earth passes Jupiter. Jupiter’s retrograde motion lasted 118 days. The duration of retrograde motion increases with superior plane’s distance from Earth. Saturn’s retrograde motion will begin February 19, 2013 and end July 9, 2013 for a total of 139 days. Watch as Jupiter appears farther from the Pleiades and closer to Aldebaran in the coming weeks. The 85% illuminated, waning gibbous Moon rises around 9 P.M. EST (depending on your location). The Moon is above the bright star Spica in Virgo and below Regulus in Leo. On Thursday, Jupiter’s moon Io crosses the gas giant’s face from 7:59 p.m. to 11:09 p.m. EST. Io’s shadow follows between 10:10 p.m. to 12:21 a.m. EST. Jupiter’s Great Red Spot crosses the planet’s central meridian around 8:07 p.m. EST. Jupiter’s Great Red Spot was a vivid brick red when discovered approximately 400 years ago. It has paled since but is still large enough to fit two or three earth-sized planets. Located 22 degrees south of Jupiter’s equator, the Great Red Spot is an anticyclonic storm which completes its counterclockwise rotation in six Earth days. Using data from the spacecraft Voyager flyblys, the wind speed on the edge of the Great Red Spot have been estimated to be 120 miles per second or 432 kilometers per hour. According to data obtained by Voyager 2’s flyby, Neptune has the strongest sustained winds of any planet in the Solar System, with recorded wind speeds as high as 2,100 kilometers per hour or 1,300 miles per hour.
The Sun sets at 5:03 PM; night falls at 6:41. Dawn breaks at 5:35 AM and ends with sunrise at 7:12.
Two planets are in the darkening sky. Jupiter is nearly due South and brightest. Mars is low in the southwest and sets around 6:30; binoculars may help find the Red Planet amid the sunset sky glow.
After nightfall, Jupiter lies between the Pleiades and Hyades star clusters. Telescopic observers can see the Great Red Spot, a gigantic storm, at about 10:30 PM. Starting at 10:39 Monday, Jupiter’s moon Europa travels across the planet’s face and exits at 1:03 AM. As Europa exits, its shadow begins its own crossing. Jupiter sets at 3:04 AM.
The seventeen-day-old Moon rises at 7 PM, and, by 9 PM, appears below Leo’s front paws. Tuesday night finds a slimmer Moon beneath the rear legs.
Comet Linear still has a faint presence in the constellation Eridanus. The 11th magnitude comet is between Beid (Omega) and Zaurak (Gamma). Medium sized telescopes should capture it.
Saturn rises after Midnight and is found between Virgo and Libra. Saturn is a treat in almost any sized telescope. Saturn lies due South at 5:58 AM.
Jupiter blazes near the Hyades star cluster, which forms the horns of Taurus, the Bull. The "V" shaped constellation points to a large pentagon, the constellation AURIGA. If the "V" is extended, the upper horn joins the bottom star of Auriga. The lower horn stops at a star below. Train a telescope at that lower star, and look just above it. The hazy patch is the Crab Nebula. On July 4, 1054, a star exploded, shone brightly in daytime, and disappeared after about a year. The Crab Nebula is all that is left, a cloud of gas and debris, expanding at 600 miles per second, with a diameter of 6 light years and 6300 light years distant. Recent studies revealed that the remnant star is a pulsar, a very dense star that does not emit light, but radiation in regular bursts. This radiation lights up neighboring gas in infrared light. This is the most conspicuous supernova remnant. In February 1987, a star in southern skies similarly exploded. Like the earlier supernova, this one became conspicuous in night skies and left behind an expanding debris cloud.
Friday, January 25th marks the 25th day of the year by the Gregorian calendar. There are 340 days left in the New Year. On Friday the Sun rises at 7:17 and sets exactly at 5:00, the very time the dead wake up and rush out of the workplace.
The Moon turns full at 11:38 PM on Saturday evening. Times of moonrise are 3:55 for Friday evening, 4:55 for Saturday evening, and 5:57 for Sunday evening.
Mercury, at superior conjunction with the Sun last week, is now emerging as an evening planet, but sets 20 minutes later than the Sun does. Only by mid-February will you be able to spot the swift and elusive planet in the evening twilight.
Mars, still low in the southwest even after many months, sets at 6:30. Mars is just now coming out of perihelion with the Sun.
Jupiter is already high up in the east by nightfall and soon afterwards will be nearly overhead and well placed for observation. The solar system’s largest planet sets at 3:20 in the morning.
The ringed planet Saturn rises at 1:00 in the morning. Only by morning twilight will it be high in the sky for best viewing. And Venus caps the morning with its rising at 6:30, 45 minutes before the Sun rises.
On this day of Friday, January 25th, 30 years ago in 1983, NASA launched IRAS, or the Infra-Red Astronomical Satellite, the first orbiting telescope that undertook a photographic survey of the entire sky in infrared light. Scanning the sky in infrared light, as opposed to visible light, allows astronomers to discover objects that are hidden by dusty regions in space and detect dim or dark planets and stars through the heat they emit.
IRAS, however, is chiefly remembered for discovering, in conjunction with British amateur astronomer George Alcock and Japanese amateur astronomer Genichi Araki, Comet 1983 H1, best known as Comet IRAS-Araki-Alcock, after its three discoverers. It was a sensational discovery that made the front pages. This comet was a long period comet that made the closest approach to Earth of any comet in 200 years at the time. It passed within 4.5 million km (or 3 million miles) of the Earth in May of 1983. During the comet’s closest approach, it shone at magnitude 3.0, appeared as large as the moon in the sky, and moved across the sky at the rate of its apparent diameter in the course of one hour.
IRAS also discovered several other comets, a few asteroids, and the dust disk around the star Vega. The spunky satellite lasted for about 10 months, its lifetime dependent on its supply of its liquid helium used to keep the telescope components cooled down to -270oC that allowed it to detect very faint and distant objects through the miniscule heat the telescope received. Today the Spitzer Space telescope, launched just 20 years after IRAS, has been performing another, more detailed infrared survey of the night sky for the past 10 years.
One of the most frequently asked questions of amateur astronomers as they offer views of celestial bodies is “How far away is that?” Let’s use this week’s night sky to answer that question about some of the most popular objects viewed by skywatchers. Although man made, the International Space Station (ISS) is wonderful addition to the dark sky as it passes 250 miles overhead while reflecting sunlight off its 240 foot long solar array. Thursday morning, the ISS will emerge out of the north-northwest at approximately 6:01 A.M. EST. The Moon reached apogee, its farthest distance from Earth this month, on Tuesday. On Wednesday evening, the 90% illuminated, waxing gibbous Moon will be approximately 251,000 miles from Earth. The distance from the Earth to the Moon varies from 225,622 miles to 252,088 miles because of the eccentricity of its elliptical orbit. This is true for planets also as they orbit the Sun. Venus rises 50 minutes before the Sun this week, and at magnitude -3.9, shines through the twilight. Venus is currently at a distance of 151 million miles from Earth or 1.624 astronomical units. An astronomical unit (AU) is the average distance of the Earth from the Sun (approximately 93 million miles). Mercury, currently hidden in the Sun’s brightness, is just past its superior conjunction, as it passes around the far side of the Sun opposite Earth. Mercury’s distance from Earth is 1.4 AU or 130 million miles. Mars, low in the southwest at sunset, is 212 million miles from Earth. Jupiter, high in the south and shining brightly at magnitude -2.5 after sunset, is 441 million miles away. Uranus is in the southwest after sunset in the constellation Pisces and is 1.9 billion miles from Earth. Neptune, in Aquarius, is 2.8 billion miles away. Beyond our solar system, the distances of celestial objects grow considerably and are measured in light years. One light year is equal to about 6 trillion miles. Sirius, the brightest star in Canis Major, and the brightest in the sky, is 8.6 light years away. To find Sirius, follow the three stars composing Orion’s belt from right to left, and look beyond on a straight line to the brightest star. The Pleiades, currently above Jupiter, is among the nearest star clusters to Earth at a distance of 424 light years. M4 is a globular cluster visible in morning skies about one degree west of the bright star Antares in the constellation Scorpius. M4 is perhaps the closest globular cluster at 7,000 light years. M42, the Great Orion Nebula, one of the brightest nebulae in the sky, can be found in the sword of Orion. M42 is 1.3 million light years away. M31, the Andromeda Galaxy, now visible almost directly overhead before midnight, is the closest galaxy to the Milky Way. The Andromeda Galaxy is approximately 2.5 million light years from Earth and visible under dark skies with the unaided eye.
The Sun sets at 4:54 PM; night falls at 6:33. Dawn breaks at 5:40 AM and ends with sunrise at 7:18.
As the sky darkens, the ten-day-old Moon glows brightly in the Southeast. Near it are the Pleiades star cluster and the planet Jupiter. All night the Moon approaches Jupiter until it lies half a degree from the giant planet. South American observers will witness the Moon eclipsing the planet. Mars lies low in the Southwest; binoculars help find it amid the Sun’s glare.
Jupiter remains up most of the night. At 8:13 Monday, the Great Red Spot, a gigantic storm, is telescopically visible. The Galilean moon Io begins its transit across the planet’s face, followed by its shadow, and ends its trip at 10:35. Tuesday at 11:40 PM, Io again accompanies the Great Red Spot across Jupiter and exits at 1:50 AM.
Nightfall sees Neptune preparing to set at 7:25. Uranus still inhabits Pisces. Astronomy magazines and websites provide observing charts.
Tonight’s telescope challenge object is Comet Linear. This 13th magnitude comet was discovered by an automated asteroid search named LINEAR. Monday night, the comet is within 1 1/4 degrees of the star named Beid, also called Omega, in the constellation Eridanus.
Saturn replaces Jupiter and the Moon, which set. The Ringed Planet glows in Virgo. At Dawn, a telescope reveals four moons to one side of the planet and the moon Iapetus on the other.
After sunset, the giant constellation Orion appears. Canis Major, the Big Dog, follows at Orion’s heels. Sirius, the Dog Star and its brightest star, is the seventh closest star to our Solar System, at 8.6 light-years. In sixty thousand years, it will approach to 7.8 light-years and increase its brightness marginally. Sirius has a companion, appropriately nicknamed “The Pup.” Telescope makers, testing a new telescope, accidentally discovered "The Pup" in January 1862. This star orbits Sirius once every fifty years. Sirius B, as the companion star is formally called, is much smaller and dimmer than the primary. The Pup is currently distancing itself from Sirius and can be seen with high powers in medium to large amateur telescopes, once Sirius' glare is blocked.
Friday, January 18th marks the 18th day of the year by the Gregorian calendar. There are 347 days left in the New Year. The Sun rises at 7:22 and sets at 4:51.
The Moon is first quarter at 6:46 on Friday evening. Over the next few days it will become a waxing gibbous Moon found high in the south at sundown. By Tuesday morning the Moon will be found ½ degree below the planet Jupiter. Times of moonset are 12:50 for Saturday morning, 1:49 for Sunday morning, and 2:46 for Monday morning.
The planet Mercury is in superior conjunction with the Sun on Friday. By month’s end, it will be visible as an evening star. Jupiter, located in the constellation Taurus, will be found high in the east after darkness falls and sets just before 4:00 in the morning. Saturn rises at 1:30 in the morning and Venus at 6:30.
Saturday January 19th marks the 7th anniversary of the launch the unmanned NASA spacecraft New Horizons towards the dwarf planet Pluto. Carrying the ashes of Pluto’s discoverer, Clyde Tombaugh, the spacecraft just last year crossed the orbit of Uranus and is currently 26 AU from the Earth but closing in on Pluto at 7 AU. New Horizons is expected to flyby Pluto and its five known moons in July of 2015 at a distance within 10,000 km (or 6,200 miles).
Although we are still a long way off before the flyby date, based on our current knowledge, let’s speculate what the spacecraft will find when it encounters the Plutonian system. Pluto, whose diameter is twice the size of Texas, has surface features that range from pitch black to bright orange and very likely has a thin frozen nitrogen surface along with traces of methane that give the orange color. Underneath the nitrogen surface is a frozen water mantle and a solid rocky core. Still near perihelion in its highly elliptical orbit of 246 years, and at its current distance of 33 AU, the Sun will appear to be very bright, about 250 times brighter than that of the full Moon here on Earth, brilliantly lighting up the Plutonian landscape. The heat from the Sun will be warm enough to vaporize the frozen surface and create a thin, tenuous atmosphere of nitrogen and methane that slowly drifts off into space blown by the solar wind, like the tail of a comet.
Five moons are known to orbit Pluto in a tight system. It appears that the moons of Pluto were very likely formed when Pluto was hit by a similar sized body that flung material into orbit around Pluto, creating the moons. That would also explain Pluto’s highly tilted axis of 120 degrees, giving long periods of darkness to parts of the planet, extreme seasonal changes, and making Pluto rotate on its side in a period of 6 Earth days. And that may well mean that Pluto’s surface may have craters. There is also the possibly that the impact may have left a thin but faint ring system around Pluto. And of course it’s very likely that another moon or two will be discovered as New Horizons encounters Pluto.
Pluto’s largest moon, Charon, has large areas of ammonium hydrates and water crystals over its surface. This suggests that Charon may be tidally heated by Pluto and may have active cryo-geysers, similar to those seen on Saturn’s moon Enceladus, from which volatiles like water and methane erupt.
We’ll have to wait another 2½ years before New Horizons arrives to prove whether parts of our scenario are correct or not. That’s the fun of astronomy and space science: using your imagination to delve into its mysteries and contemplate the unknown while using your brain to forever search for the answers.
Comets have been in the news recently, specifically Comet ISON, officially catalogued as C/2012 S1. Discovered on September 21, 2012, Comet ISON will reach perihelion on November 28, 2013. ISON is currently passing through the constellation Gemini, and will be a half of one degree south of the star Castor on January 16th. At a distance 474 million miles, ISON is still very faint, at about 16th magnitude. It is uncertain how bright Comet ISON will become, but estimates are as bright as -12.6 magnitude, the brightness of the full Moon. Another comet in the news is PanSTARRS. This comet was first discovered using the PanSTARRS telescope on Maui, Hawaii, in 2011. Comet PanStarrs, also known as C/2011L4, is expected to be as bright as Venus this March.
A comet that can be seen these days is Comet C/2012 K5 (Linear). On Wednesday night, Comet C/2012 K5 (Linear) can be found to the right of Orion’s brightest star, Rigel, at the constellation’s foot and 17 degrees below Aldebaran, the bright reddish star below Jupiter in the constellation Taurus. The orbital elements of the brightest comets can be found on the website www.heavens-above.com. The 30% illuminated, waxing crescent Moon can be utilized on Wednesday night to find Uranus. Uranus, visible at magnitude 6.21, will be located less than one degree to the left of the crescent Moon. The Moon will set approximately fifteen minutes before midnight EST. As the Moon is setting, Jupiter will be higher in the southwestern sky to the right of Aldebaran. Saturn rises at around 1:30 A.M. EST between the constellations Virgo and Libra. Thursday’s pre-dawn sky features Venus, which rises in the southeast at 6:20 A.M. EST. Sunrise follows an hour later. Mercury is at superior conjunction, the opposite side of the Sun than the Earth, at 4 A.M. EST Friday.
The Sun sets at 4:46 PM; night falls at 6:26. Dawn breaks at 5:43 AM, ending with sunrise at 7:23.
The three-day-old Moon rose this morning as a slim crescent moderately high in the southern sky and sets at 8:35 PM. Tuesday sees a fatter Moon higher in the sky and setting an hour later.
Mars, low in the southwest, sets at 6:28 PM. Binoculars may help find it amid the sunset glare.
Jupiter is high in the southeast. Monday evening, at 7:46, its Moon Europa begins crossing the planet’s face, and ends the trek at 10:10. Tuesday evening, the moon Io begins its crossing at 9:51 and ends at 1 AM Wednesday. Both events are best observed through telescopes.
Nightfall reveals Neptune and Uranus. Monday finds Neptune seven degrees below the Moon; Tuesday, the Moon moves to sixteen degrees West of Uranus. Both planets set by 10:40 PM.
Jupiter is solitary at Midnight. Saturn rises at 1:36 AM. At 3 AM, an observer can see both planets: Saturn risen in the East, Jupiter preparing to set at 4 AM.
Even though the shortest day was December 21, sunrises have been later, until January 4th. Early risers can telescopically observe Saturn at a more convenient time. Its rings are tipped nineteen degrees toward us; in addition, Saturn is side-lit by the Sun. This circumstance provides the best views of the Ringed Planet since 2006.
By nightfall, Orion is high in the southeastern sky. The bright white star Rigel marks the hunter’s knee. A dim line of stars begins at Rigel and flows westward and downward until it disappears below the horizon. This is the river Eridanus. To see the entire heavenly waterway, one must travel South. Eridanus ends with Achernar, which means, “star at the river’s end.” Ancient authors differ as to whether it refers to the Euphrates or the Nile. Both were revered from time immemorial as the sources of water and bountiful harvests. The ancients thought of Earth as an island surrounded by a great body of water. The story in the Book of Genesis and Babylonian creation myths allude to this view. For the past several months we have observing water related constellations: Delphinus, Capricornus, Aquarius, Cetus and Pisces. Eridanus spills its heavenly waters to sustain the celestial aquarium.
Friday, January 11th marks the 11th day of the year by the Gregorian calendar. There are 354 days left in the New Year. The Sun rises at 7:25 and sets at 4:42. The length of daylight is now becoming noticeably longer.
Happy “Old New Year!” Monday, January 14th marks Old New Year’s Day as observed by the countries that only relatively recently dropped the older Julian calendar, now 13 days behind our currently used Gregorian calendar. This holiday is celebrated by many Slavic countries such as Russia, Serbia, and Slovakia and even Switzerland and Wales.
The Moon is new at 2:44 PM on Friday. Over the next few days it will become a thin, very young waxing crescent Moon setting in the west-southwest near the planet Mars. Times of moonset are 5:22 for Friday evening, 6:33 for Saturday evening, and 7:43 for Sunday evening. Jupiter still reigns as king of the night sky as it arcs high overhead long after dark. Saturn rises at 2:00 in the morning and Venus at 6:15.
On this day of January 11th, in the year 1610, the famous Italian astronomer Galileo Galilei, after five days of observing the planet Jupiter with the aid of his own spyglass, as telescopes were called back in his day, had “decided beyond all question that there existed in the heavens three stars wandering about Jupiter as do Venus and Mercury about the sun,” as he later wrote in his book Siderius Nuncius, or The Starry Messenger, published the following March. Galileo had just discovered three of the four largest moons of Jupiter. He soon discovered the fourth moon and named all the moons the Medicean stars, in hopes of currying funding and favors from the noble Italian de Medici family.
However, a German astronomer, Simon Mayr, would four years later in a publication titled Mundus Jovialis or The World of Jupiter claim that it was he who had discovered the moons in 1609, earlier than Galileo did. Unlike Galileo, who kept a meticulous record of his observations, Mayr had produced only one observational record of seeing three of the moons, located in the same positions as Galileo had first sketched them on January 7th. Galileo noticed that and rightly charged that Mayr had plagiarized Galileo's own observation. Galileo also pointed out, quite correctly, that Mayr’s claim of discovery on December 28th, 1609, was the date by the Julian calendar still in use by the Protestant Germans. This date was the same date as Galileo’s first day of his series of observations starting January 7th, 1610, by the Gregorian calendar in use by the Italian Catholics. Today, historians credit Galileo for the discoveries of the Jovian moons.
But Mayr also took the liberties of naming the moons of Jupiter, calling them Io, Europa, Ganymede, and Callisto, taken from ancient Greek mythology. Nevertheless, for over three hundred years astronomers neither referred to the moons as the Medicean stars, nor even by the names given by Mayr. Instead the four moons were referred to by the Roman numerals in the order of increasing distance from Jupiter – I, II, III, and IV, as can be seen in astronomy text books from the time. It wasn’t until sometime during the early 1900s did astronomers begin using the present day names of the four largest moons of Jupiter. But with well deserved respect to Galileo and his discovery, the four moons are also referred to as the Galilean moons. The Medicean names have simply been dropped.
With the New Moon approaching, this week’s evening sky provides an opportunity to explore some deep sky objects directly overhead. Follow the constellations up from the eastern horizon to the zenith. About two hours after sunset, the constellations Gemini and Orion are fully apparent on the eastern horizon. Above Orion is Taurus, where -2.7 magnitude Jupiter will be above Aldebaran and below the Pleiades. Above and left of Taurus will be the constellation Auriga and its brightest star, Capella. At magnitude -0.51, Capella is the eleventh brightest star in the night sky and the third brightest star in the northern celestial hemisphere, after Arcturus and Vega. Capella is one of the stars in the Winter Hexagon along with Aldebaran in Taurus, Rigel in Orion, Sirius in Canis Major, Procyon in Canis Minor and Pollux in Gemini. Capella is a binary star system consisting of type G yellow stars, like our Sun. Capella’s component stars are only separated by 60 million miles, about the distance from the Sun to Venus, and therefore very difficult to split using a telescope. Auriga also contains three of the winter’s brightest open star clusters, M36, M37 and M38. You’ll locate M38 at the center of Auriga’s pentagonal shape. M36 and M37 are east of M38. M36 and M38 can be viewed in the same field through a low power telescope. M36 is the smaller, but brighter of the two star clusters and contains 60 stars of magnitudes 9 to 14. M37 contains more than 500 stars, with approximately 150 stars brighter than magnitude 12.5. Thursday morning, the thin 3% illuminated, waning crescent Moon is at perigee at the distance of 223,723 miles from Earth. Between 6:30 and 7 A.M. EST, the crescent Moon will pass just 3 degrees north of Venus low on the southeastern horizon an hour before sunrise.
The Sun sets at 4:38 PM; night falls at 6:19. Dawn breaks at 5:44 AM, ending with sunrise at 7:25.
After sunset, two bright planets are visible. Mars lies low on the southwestern horizon. Binoculars may help find the planet amid the Sun’s glare. Mars set at 6:26.
Jupiter blazes moderately high in southeastern skies. As the sky darkens, a beautiful star cluster, the Pleiades, lies about nine degrees above the giant planet.
Nightfall permits telescopic observation of some of Jupiter’s moons. Monday, at 7:34 PM, the moon Europa emerges from Jupiter’s shadow; Tuesday at 8 PM, Io crosses Jupiter’s face, followed by its shadow.
Neptune and Uranus occupy Aquarius and Pisces. Astronomy magazines and websites have observing charts. Both set by 11 PM.
Saturn rises at 2 AM, joining Jupiter. At about 4 AM, each planet is visible at opposite horizons. One must work quickly, since Jupiter sets at 4:30.
Tuesday’s slim crescent Moon rises at 3:54 AM near the head of Scorpius. Wednesday, a slimmer crescent emerges at 5 AM near the Scorpion’s middle. Venus rises about 6:08 to the Moon’s lower left.
Sunday, January 6th was the Christian feast of the Epiphany, otherwise known as “Three Kings Day.” Who were these “kings?” Most likely they were Magi from Babylon. Babylonians were famous for astronomical skill. By 2000 BC, they identified all five visible planets, major constellations, the zodiac, and the Saros cycle of eclipses. These priest-astrologers were powerful and respected throughout the known world.
These dedicated sky watchers would certainly notice any new event in the night sky. While some think that a comet or supernova may have been the “Christmas Star.” Prevailing opinion is that it may have been an astrological event; the most likely being a triple conjunction between Saturn and Jupiter during the year 7 BC. That year, Jupiter appears to: chase Saturn, pass it, turn around, pass Saturn again, and finally pull alongside Saturn one more time before sailing past it. This startling series of events took place in Pisces, a significant constellation. To them, stars and planets were divine messengers. When planets, associated with the most powerful gods, kept meeting, the Magi knew something significant was about to happen. They were also familiar with their neighbors. Search of Jewish literature provided the inspiration to set off for a meeting with a new god-king.
Friday, January 4th, of course, marks the 4th day of the New Year. There are 361 days left in this year. The Sun rises at 7:26 and sets at 4:35. Friday, January 4th also marks the date of the latest sunrise of the year. And the morning of Monday, January 7th marks the latest onset of morning twilight. After this weekend, the lengthening days will also include progressively more daylight in the morning. Now you have an incentive to wake up early on these dark, cold winter mornings.
On this day of January 4th in the year 1959, the Soviet spacecraft Luna 1, launched just two days previously, became the first man-made object to escape the gravitational pull of the Earth. Luna 1 was targeted for a crash landing on the Moon. But the space probe missed its target and flew by the Moon instead, becoming the first spacecraft to perform a flyby of the Moon at a distance of 6,000 km (or 3,700 miles) and still make scientific measurements before going into solar orbit. This was an impressive achievement for its time, coming just two years after Sputnik 1. Shortly thereafter, the Soviets were also able to launch Luna 2, in that same year, as the first spacecraft to crash land on the Moon. This was quickly followed by Luna 3, also in that same year, as the first spacecraft to take photos of the far side of the Moon - a rapid succession of space firsts that startled the lagging Americans with their fledgling space program barely getting off the ground. Luna 1, by the way, is still orbiting the Sun in between the orbits of Earth and Mars.
The Moon is at last quarter at 10:58 Friday evening. On Saturday morning, the waning Moon will be found about 1 degree south of the star Spica and on Sunday morning it will be found 4 degrees south of the planet Saturn. Times of moonrise are 12:24 for Saturday morning, 1:34 for Sunday morning, and 2:44 for Monday morning.
While Mars sets very shortly after the Sun does, Jupiter will be found high in the sky after evening twilight, excellent for viewing. You will have to wait until 2:30 to catch Saturn rising in the east. As for Venus, it rises at 6:00 in the morning, falling ever closer to the Sun as the weeks go by.
Now that we have our old-fashioned, cold winter days back, at least for a while, with clear frosty skies, for a little bit of warmth look to the southeast for the Dog Star Sirius of the constellation Canis Major. At magnitude -1.5, Sirius is the brightest star in the night sky and has a mass twice that of the Sun and a diameter about 1 1/2 times larger than that of the Sun. It lies at a distance of 8.6 light years away, not very far at all. Sirius is also a double star, with its companion called Sirius B, a massive white dwarf of magnitude 8.3, and orbiting the brighter star with a period of about 50 years. Sirius B may have once been the brighter and more massive of the double star system, before flaring into a red giant and dying down to the faint white dwarf it is now. The name Sirius was given by the ancient Greeks, which stands for “scorcher”, because when Sirius was in conjunction with the Sun during the summer, and thus rising and setting with the Sun, it was believed that the heat from Sirius would then combine with the heat from the Sun which thus brought on the so-called dog days of summer. And although Sirius is bluish-white in color, when it is low above the horizon it rapidly twinkles with a rainbow of colors ranging from blue to red to orange to white and then back to blue.
On Wednesday, shortly after midnight EST, Earth reaches perihelion, its closest approach to the Sun in its elliptical orbit. Earth will be 91,402,560 miles from the Sun, approximately 1,600,000 miles from its average distance, or one astronomical unit (92,955,807 miles). The difference in distance between perihelion and aphelion, Earth’s furthest distance, is 3%. Aphelion occurs on July 5th this year. Mars remains low on the southwestern horizon, between and below, the bright star Fomalhaut to the south, and Altair to the west, and is a challenge to view in the evening’s twilight. Fomalhaut is the brightest star in the constellation Pisces and is approximately 25 light years from Earth. Fomalhaut is the center of the first stellar system with an extrasolar planet imaged at visible wavelengths. Neptune is about 25 degrees west of Fomalhaut in the constellation Aquarius. Uranus can be found 35 degrees above Fomalhaut in the constellation Pisces and sets three hours after Neptune. To the east, Jupiter is high in the constellation Taurus, between the Hyades and Pleiades star clusters. The 70% illuminated, waning gibbous Moon rises at 10:10 P.M. EST in Virgo. Saturn rises at 2:18 AM Thursday. Jupiter and Saturn can be seen at the same time about 10 degrees above opposite horizons, Jupiter in the west-northwest and Saturn in the east-southeast, 3 and one half hours before sunrise. Venus is almost at the end of its morning apparition and rises only one and one half hours before the Sun. The Quandrantid Meteor shower peaks early Thursday morning. Normally one of the strongest of the year, this year’s shower is expected to be unfavorable. The Quandrantids originated from asteroid 2003 EH1 and appear to emanate from an area of the sky known as Quadrans Muralis, around the northern tip of the constellation Bootes. Bootes will be high in the early morning southwestern sky. Follow he Big Dipper’s arching handle to Arturus, Bootes’ brightest star. The glare of the gibbous Moon will inhibit viewing the estimated 80 meteors per hour in the early morning sky.
The Sun sets at 4:31 PM; night falls at 6:13. Dawn breaks at 5:44 AM and ends with sunrise at 7:26. As the sky darkens, Jupiter is the brightest object in the southeastern sky. Binocular observers can see all four Galilean moons about a half hour after sunset. The satellite Callisto is to one side of Jupiter while Europa is close on the other side, followed by Io and Ganymede.
Mars continues to hang on in the southwest. It lies about eleven degrees above the southwestern horizon. Binoculars may help find it amid the sun’s glare. Mars sets before 6:30.
The giant planet Uranus lies due South at 5:30 PM, making its observation easier. The sixth magnitude blue-green ball makes it distinctive. Fellow gas giant Neptune is lower in the southwest, amid the stars of Aquarius. Charts for these planets are available in astronomy magazines and websites. Both set by 11:30 PM.
The eighteen-day-old Moon rises after 8 PM and illuminates the feet of Leo, the Lion. Saturn rises at 2:26 AM between Virgo and the scales of Libra. Saturn is a treat in any size telescope. Venus rises at Astronomical Dawn and is eight degrees high by 6:54 AM; it can be found 41 degrees to Saturn’s lower left. Under high power, Venus appears almost “full.”
Tuesday is, of course, New Year’s Day. Other cultures celebrate different days. For some, it is the Spring Equinox, others the Winter Solstice. Ancient Egyptians marked the rising of the star Sirius. Chinese celebrate New Year’s between January 20th and February 20th due to a lunar calendar. New Year’s Day also varies in the lunar Islamic calendar. Western calendars begin on January First – thanks to Julius Caesar. The Roman calendar was a mess; it contained 354 days. Extra months had to be inserted to keep in step with the Sun. While Caesar courted Cleopatra, he met her astronomer, Sosigenes, who recommended calendar reform. Caesar adopted those suggestions. On January First 45 BC, the new calendar became effective. It called for 365 days and twelve months. A leap year would be added every four years, to keep the calendar in sync with the Sun. With minor changes, this is the calendar we now use.
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