This is Dudley Observatory’s Skywatch Line for Friday, September 28 through Sunday, September 30, 2018

This is Dudley Observatory’s Skywatch Line for Friday, September 28 through Sunday, September 30, written by Sam Salem.  On Friday, the Sun rises at 6:50am and sets at 6:42pm; the waning gibbous Moon sets at 10:16am and rises at 9:00pm. Late on Friday evening, spot the Pleiades upper left of the Moon. Try to locate Pleiades’ tiny dipper pattern standing on its handle. On Saturday night, the waning gibbous Moon slowly drifts through the Hyades cluster in constellation Taurus. As it exits the cluster, the lunar disk passes within ½ degree, one Moon diameter, of the constellation’s brightest star Aldebaran. The Moon is nearest Aldebaran around 2am on Sunday Morning.

Venus is at its peak brilliancy of magnitude –4.8, shining very low in the west-southwest after sunset. It sets in late twilight. Venus sits down to Jupiter’s lower right. Their separation remains steady this week at 14 degrees. In a telescope Venus is a crescent, about 25% sunlit and 41 arc-seconds tall. Mars, in southern constellation Capricornus, fades from magnitude –1.5 to –1.3. It shines highest in the south soon after dark and sets around 2am. Jupiter, in constellation Libra, shines at magnitude –1.8 ever lower in the southwest in twilight, upper left of Venus. Saturn is already at the meridian when the Sun sets. Saturn sits in constellation Sagittarius, low in the south. However, Saturn’s magnificent rings will be apparent. The ring system, measured tip to tip, currently appears about as wide as Jupiter’s disk. The rings are tilted toward Earth by an angle of 26 degrees, which is only one degree shy of maximum. This permits easier sightings of the 4,700-kilometre-wide Cassini’s Division gap that separates Saturn’s two brightest rings. During moments of steady seeing, the threadlike feature is visible even in a 60mm refractor.

This weekend look for the loneliest star, Fomalhaut, the bright star located in a region of the sky that contains only very faint stars. Fomalhaut is a bright star in the constellation Piscis Austrinus, the Southern Fish. It is bright enough to be seen on a moonlit night. Fomalhaut rises at 7:26pm and sets at 3:24am, reaching transit altitude of 18 degrees south before midnight on Friday. No other bright star sits so low in the southeast at this time of year. Fomalhaut sits close the southern horizon until well after midnight on these fall nights. Fomalhaut is the brightest white star in an otherwise empty-looking part of the sky. The star is sometimes called the Lonely One, the Solitary One, or sometimes the Autumn Star. Fomalhaut is the 18th brightest star in the sky. The Arabic name, Fomalhaut, means “mouth of the fish” or whale. In 2008, Fomalhaut became the first star with an extrasolar planet candidate imaged at visible wavelengths. The image was published in the journal Science in November 2008. Fomalhaut is the third-brightest star known to have a planetary system, after the star Pollux in the constellation Gemini and our own Sun.

This is the Dudley Observatory Skywatch Line for Wednesday, September 26th, and Thursday, September 27th, 2018

This is the Dudley Observatory Skywatch Line for Wednesday, September 26th, and Thursday, September 27th, written by Louis Suarato.  The 96% illuminated, waning gibbous Moon rises in the constellation Pisces at 7:56 p.m. Wednesday. There are two separate motions that affect our perception of the Moon’s path across the sky. The first is Earth’s rotation toward the east. As the Earth rotates away from the Moon, it appears to move across the sky a the rate of 15 degrees per hour, the result of dividing a 360 degree circle by 24 hours. The second is the Moon’s own eastward motion at the rate of .55 degrees per hour, or 13.2 degrees per day. This eastward motion by the Moon, changes its position in front of fixed background stars from night to night. As the Moon is rising, Jupiter is setting in the west-southwest. With Venus and Jupiter gone from the night sky, Mars and Saturn remain the only naked-eye visible planets. Saturn sets at 11:14 p.m., and Mars will set at 1:31 a.m. Thursday. As for a not-so-easily visible planet, use binoculars, or a small telescope, to look for Uranus 5 degrees above the Moon at 3 a.m., Thursday..

Comet 21P/Giacobini-Zinner has moved beyond Gemini and into the constellation Monoceros. Look about 20 degrees to the upper left of Sirius, which is the very bright star above the southeastern horizon at 4 a.m., for this green comet. Comet 21P will be 2 degrees to the east of the Rosette Nebula. The Rosette Nebula, also known as Caldwell 49, is a large cluster of stars surrounded by a nebulous cloud. It is comprised of nebulous regions NGC 2237, NGC 2238, NGC 2239, and NGC 2246, and an open star cluster NGC 2244, within the nebula. The Rosette Nebula, located about 5,000 light-years from Earth, was discovered in 1690 by John Flamseed.

September 27 is the birth date of astronomer Benjamin Gould, the first director of the Dudley Observatory. Born in Boston, Massachusetts in 1824, Gould served as director from 1855 to 1859. Gould was also in charge of the longitude department of the United States Coast Survey, where he was one of the first to determine longitude by telegraphic means. Gould’s greatest work was compiling a catalog of stars in the southern hemisphere while he was in Argentina.

This is the Skywatch Line for Monday and Tuesday, September 24th and 25th, 2018

This is the Skywatch Line for Monday and Tuesday, September 24th and 25th.  The Sun sets at 6:49 PM; night falls at 8:23. Dawn begins at 5:11 AM and ends with the Sun rising at 6:46. Note that since the Equinox happened on Sunday, the amount of daylight is now less than 12 hours.

The evening planetary parade continues. Venus, in Virgo, hovers 3º above the western horizon. Binoculars reveal it about 23% lit and blazing at minus 4th magnitude. Venus sets at 7:41 PM.

Jupiter continues to reside in western Libra and shines with minus 1st magnitude. It still appears relatively large in our instruments with 33 arc-seconds in size. The giant planet sets at 8:51 PM.

Still moving East, Saturn, in southern Sagittarius, shines with zero magnitude and appears about half of Jupiter’s size. Evening is the best time to appreciate its beautiful ring system, since it sets at 11:24 PM. Saturn is also at Quadrature, which means that it is 90º east of the Sun and the Sun’s angle makes the rings seem even more glorious.

Mars resides in southeastern Capricornus and shines with minus 1st magnitude. It appears almost as large as Saturn in our telescopes and is about 90% illuminated. The Martian dust storm continues to abate, providing improving views of surface features. Astronomical media provide charts, which identify those features. Mars is best observed at 9:08 PM and sets at 1:37 AM.

The Venus-Jupiter-Saturn-Mars group spans about 85º degrees during twilight.

Neptune, in Aquarius, is already risen, shines with 7th magnitude and is 11º high in the East. It is best observed at 11:44 PM and sets at 5:20 AM. Uranus, in Aries, glows brighter with 5th magnitude and is slightly larger, about 4 arc-seconds in size. It rises at 7:48 PM and is best examined at 2:38 AM. Both planets require detailed charts from astronomical media.

The variable star Algol, in Perseus, dims at 4:09 AM on Tuesday. The cycle begins 2 hours in advance and ends 2 hours after minimum. However, the brilliant Moon may hinder observation.

The Moon rises in Pisces at 7:02 PM on Monday, and in Cetus at 7:29 PM on Tuesday. The Moon turns full at 11:52 PM on Monday. This is the famous Harvest Moon, defined as the Full Moon nearest the Autumn Equinox. The Harvest Moon is special because the fall harvest could be conducted without daylight. Usually the Moon rises about an hour later each night. However, due to the shallow Moon’s path in the sky, called the ecliptic, this time of the year has the Moon rising between twenty minutes and a half hour later. This effect becomes more noticeable as you head to more northern latitudes. Pre-tractor farmers had the Moon to work by. This grace period lasts only until the moonrise gradually lengthens to its average interval of about 75 minutes.

Astronomers are not the only observers of the night sky. The Harvest Moon also provides bird watchers with plenty to document. This time of the year, birds start heading south for the winter. They fly mainly at night to conserve energy and avoid predators. It is not unusual to witness flocks flying across the Moon’s disk, and now is the best time, weather permitting.

This is Dudley Observatory’s Skywatch Line for Friday, September 21 through Sunday, September 23, 2018

This is Dudley Observatory’s Skywatch Line for Friday, September 21 through Sunday, September 23, written by Sam Salem.  On Friday, the Sun rises at 6:42am and sets at 6:55pm; the waxing gibbous Moon sets at 3:01am and rises at 5:35pm. Full Moon occurs on Monday at 10:52pm. On Saturday after dark, watch the Great Square of Pegasus balances on one corner about three fists at arm’s length to the left of the gibbous Moon. The Square’s upper right side points down toward the Moon.

On Saturday, the Sun crosses the celestial equator at 9:54pm, marking the equinox and the beginning of fall season in the northern hemisphere. On the day of the equinox, the Sun rises due east and sets almost exactly due west. Day and night are almost equal. Coincidentally, when summer turns to autumn, Deneb takes over from brighter Vega as the zenith star after nightfall.

Venus reaches its peak brightness of magnitude –4.8 on Friday evening. Unfortunately, the planet is very low in the west at sunset and difficult to sight. In telescopes Venus displays a tiny, snow-white crescent. This distinctive shape is best observed in the afternoon, around 3:30pm when the planet is highest and its brightness isn’t overwhelming.

Mars, in southern Capricornus, fades from magnitude –1.7 to –1.5. It is still a trace brighter than Sirius. Mars shines highest in the south about an hour after dark and sets around 2am. In a telescope Mars shrinks from 18½ to 17 arc-seconds wide. Jupiter, at magnitude –1.9, shines ever lower in constellation Libra in the southwest in twilight. Jupiter is still very close to the double star Zubenelgenubi, or the southern claw in Arabic, in constellation Libra, but it is slowly drifting farther away from it. Saturn, at magnitude +0.4, sits above the spout-tip of the Sagittarius Teapot in the south at dusk. It’s located well to the right of brighter Mars. Saturn sets by midnight.

This weekend represents the last best chance to enjoy Comet 21/P Giacobini-Zinner. After this weekend, moonlight will start lighting up the predawn sky, where the comet is found. 21/P is beginning to fade as it recedes both from the Sun and the Earth. Find Giacobini-Zinner this weekend moving its way through southern Gemini and into constellation, Monoceros. On Monday morning, the comet drifts alongside the 4th-magnitude open cluster, NGC2264, the Christmas Tree Cluster. This same NGC number also refers to the much fainter Cone Nebula. Try to capture the cluster, nebula and comet together this weekend. The Moon sets as twilight begins. For this reason, Sunday might be a better choice to capture the scene with your camera.

Sunday marks the 172nd. Anniversary of the discovery of planet Neptune. The German astronomer Johann G. Galle discovered Neptune on September 23 1846, after only an hour of searching, within one degree of the position that had been computed by Urbain-Jean-Joseph Le Verrier. Irregularities in the orbit of Uranus led to the belief that another celestial body might be responsible for the gravitational pull. The size and position of Neptune were calculated independently by the English astronomer John Adams and the French astronomer Urabain-Jean Le Verrier based on Neptune’s influence on Uranus’ orbit. Neptune goes around the Sun once roughly every 165 Earth years. In the year 2011, Neptune completed its first orbit since being discovered.


Skywatch Line for Wednesday, September 19th, and Thursday, September 20th, 2018

This is the Dudley Observatory Skywatch Line for Wednesday, September 19th, and Thursday, September 20th, written by Louis Suarato.

The 76% illuminated, waxing gibbous Moon rises at 4:20 Wednesday afternoon. At nightfall, Mars will emerge four and a half degrees below the Moon. Both Moon and Mars will be between the constellations Capricornus and Sagittarius. The Moon reaches apogee, its furthest distance from Earth during this lunar cycle, on Wednesday at 8:53 p.m., at the distance of 251,578 miles. Look to the south for Saturn still nestled in the Milky Way that forms the steam of the Teapot asterism. Jupiter will be found low above the south-southwest horizon. After months of opportunities to see all the easily visible planets, they are slowly leaving the night sky.

With the approach of Fall, look for the star, Fomalhaut, the Autumn Star, rising to the lower left of the Moon, out of the southeast horizon. Fomalhaut is the brightest star in the constellation Piscis Austrinus. Fomalhaut, which translates to “mouth of the whale”, is estimated to be 25 light-years away, and is approximately 440 million years old. With a diameter of 1.84 times that of our Sun, Fomalhaut’s luminosity is 16.6 times brighter. Located in an area devoid of other bright stars, Fomalhaut is also known as “the loneliest star”. Fomalhaut is the 18th brightest star in the sky, and second brightest only to Pollux, known to have an exoplanet.

Comet 21P/Giacobini-Zinner, now reflecting light at magnitude 7.17, can be found at the feet of Gemini. Look 12 degrees to the left (east) of Betelguese in the early morning sky for Comet 21P. Use binoculars, or a telescope, to see this bright green comet.

The Albany Area Amateur Astronomers invite you to join them for their monthly meeting to be held Thursday night, at miSci, beginning at 7:30. The guest speaker is Matthew Syzdagis, Ph.D., who will discuss “What Astronomical Phenomena Could Permit Time Travel?” Dr. Syzdagis is an assistant professor of physics at SUNY Albany who does research in “experimental astroparticle physics, in particular direct detection of dark matter WIMPs (Weak Interacting Massive Particles), and general detector development for rare event searches”.

Skywatch Line for Monday and Tuesday, September 17 and 18, 2018

This is Dudley Observatory’s Skywatch Line for Monday and Tuesday, September 17 and 18, written by Alan French.

The Moon reached first quarter Sunday afternoon, having completed one quarter of its trip around Earth since the last new Moon. At first quarter we see one half of the illuminated, day side of the Moon and one half the night sight. By Monday night the Moon will have traveled farther around our Earth and we’ll see more than half the sunlit side – a waxing gibbous Moon. By Tuesday even more of the visible face of the Moon will be in sunlight. The Moon will reach full on Monday, September 24.

On Monday night the Moon, due south at 7:35 pm, will be close to Saturn, which will be just three degrees west (right) of the lunar limb. The Moon moves eastward among the stars and by Tuesday night will lie roughly half way between Saturn and Mars.

A pair of steadily held binoculars will show the larger lunar craters and other large features, far more than you can see by eye alone. Although amateur astronomers prefer viewing when targets are high in the sky, so they are viewing through a thinner layer of atmosphere, it’s easier to hold binoculars steady when they are aimed lower. It’s also more comfortable. The Moon is now roughly 24 degrees up when due south, an agreeable altitude for binocular viewing.

Any telescope magnifying 30 to 60 times will reveal a greater wealth of detail in the lunar landscape. Detail is best seen along the terminator, the line dividing the sunlit portion of the Moon from the part still in darkness. As we move toward full this is the sunrise line. Along the terminator the Sun is low in the lunar sky and shadows are long, so detail stands out in bold relief.

Look for points or lines of light just over into darkness. These are mountain tops and crater walls just catching the light of the rising Sun. The rising Sun will slowly bring more features into view. Some changes may be visible over 10 or 15 minutes, so pick out a few features near the terminator to check regularly over the evening. Pick an obvious crater Monday night and make note of its appearance, or make a quick sketch, and look back again Tuesday night.

It takes some patience and practice, but people have gotten some reasonable lunar photos by pointing their camera phone into a telescope’s eyepiece. Why not give it a try?

The Moon sets at 12:21 am Tuesday and 1:11 am Wednesday.

Skywatch Line for Friday, September 14 through Sunday, September 16, 2018

This is Dudley Observatory’s Skywatch Line for Friday, September 14 through Sunday, September 16, written by Sam Salem.

On Friday, the Sun rises at 6:34am and sets at 7:07pm; the waxing crescent Moon rises at 11:54am and sets at 10:17pm. The first quarter Moon occurs on Sunday at 7:15pm. On Friday twilight, catch the crescent Moon in the southwest with Jupiter to its lower right. On Saturday, the Moon hangs over Antares at nightfall. Saturn, then Mars, sit far to the Moon’s left. To the Moon’s lower right is Jupiter. Look far to Jupiter’s lower right to catch Venus before it sets. Venus, at magnitude –4.7, shines low in the west-southwest in evening twilight and sets before twilight is over. In a telescope Venus is a crescent about 1/3 sunlit. For better telescopic seeing, catch Venus higher in blue sky long before sunset. Jupiter, at magnitude –1.9, in Libra, shines in the southwest in twilight. Saturn, at magnitude 0.4, glows in the south at nightfall above the spout-tip of the Sagittarius Teapot, well to the right of brighter planet Mars. Mars is at closest point to the Sun, or perihelion, on Sunday, nearly seven weeks after its closest approach to Earth. Mars sits between constellations Capricornus and Sagittarius. Shining at magnitude –1.8, Mars is still brighter than Sirius. Mars shines at its highest in the south for two hours after dark. Although its disk has shrunk from its 24.3 arc-second to 18.8 arc-seconds, Mars is still an attractive object for telescopic observing.

Comet 21/P Giacobini-Zinner was at its peak brightness as it was closest to Earth last weekend. Giacobini-Zinner will fade as it recedes from the Sun. After next weekend, the Moon will return to the morning sky and interfere with the view. On Saturday morning, the 7th magnitude comet passes in front of the 5.1 magnitude open cluster, M35, located in southwestern Gemini. At roughly 4:20am, the center of the comet passes in front of the brightest cluster member, which shines at magnitude 7.4. At around 5:30am, Giacobini-Zinner is nearest the cluster’s center. At that time the comet is also highest before morning twilight. It will take roughly five hours for the comet to completely traverse M35. With a small telescope you can watch the comet slowly slide across this famous Messier object as the wee hours tick by.

The star Mirach, or Beta Andromedae, in the constellation Andromeda acts as the guide star to three different galaxies: the Andromeda galaxy (M31), the Tiangulum galaxy (M33), and NGC 404. Draw a line from the star Mirach through the star Mu Andromedae to locate the Andromeda galaxy. A line drawn in the opposite direction from the star Mu Andromedae through the star Mirach takes you in the direction of the Triangulum galaxy. This often-photographed galaxy is a nearby face-on spiral galaxy. Mirach sits midway between the Andromeda and Triangulum galaxies. M31 and M33 weren’t recognized as galaxies until the 20th century. Before then, these faint fuzzies were referred to as nebulae. In the later 18th century Charles Messier listed M31 and M33 as masquerade comets in his famous Messier catalogue. The Andromeda’s star Almach, or Gamma Andromedae, appears in a telescope as one of the finest double stars. It is often considered by stargazers to be a beautiful double star with a striking contrast of color. One component of this telescopic double appears golden, and the other component appears indigo blue separated by approximately 10 arc-seconds. It was later discovered that the indigo blue companion is itself a triple star system.

Skywatch Line for Wednesday, September 12th, and Thursday, September 13th, 2018

This is the Dudley Observatory Skywatch Line for Wednesday, September 12th, and Thursday, September 13th written by Louis Suarato.

Look over the south-southwestern horizon after sunset, at about 7:30 p.m., to see the 12% illuminated, waxing crescent Moon 8 degrees above setting Venus. Look 17 degrees to the southwest of the Moon for Jupiter in the constellation Libra. Thursday night, the crescent Moon and Jupiter will be 4.5 degrees apart. Moonset occurs at 9:11 p.m., followed by Jupiter 20 minutes later, leaving Saturn and Mars as the only remaining easily visible planets. The red and ringed planets will be flanking Sagittarius above the southern horizon.

Comet 21P/Giacobini-Zinner, just past its closest approach to Earth in 72 years, is approaching star cluster M35 at the northern-most foot of Gemini. At about 3 a.m., Comet 21P will be 79 degrees above the eastern horizon, about 20 degrees to the lower right of Auriga’s brightest star, Capella. Comet 21P is a 7.05 magnitude, and can easily be seen through binoculars. The comet will reach M35 in the early hours of Sunday. M35 is an open star cluster discovered by Philippe Loys de Chéseaux in 1745. This star cluster is about the size of the Full Moon, and consists of several hundred stars, of which 120 are brighter than 13th magnitude. It has an overall apparent magnitude of 5.3, and is estimated to be 2,800 light-years away and 110 million years old. M35 is the only Messier object in Gemini.

To the southeast, or right of Comet 21P/Giacobini-Zinner is M1, the Crab Nebula. This supernova remnant, chronicled by Chinese astronomers in 1054, was visible during the daylight hours for 23 days, shining 6 times brighter than Venus. This stellar explosion was naked eye visible for nearly another two years. Look 15 degrees to the right of Comet 21P/Giacobini-Zinner for the Crab Nebula. Binoculars will reveal this comet to be a fuzzy blob, similar to the way Messier must have seen it, comet-like, and not the comet he was searching for.

Skywatch Line for Monday and Tuesday, September 10 and 11, 2018

This is Dudley Observatory’s Skywatch Line for Monday and Tuesday, September 10 and 11, written by Alan French.

The Moon was new Sunday afternoon. If you have an excellent view to the west and clear skies down to the horizon watch for a slender Moon on Monday night. Look at 7:45 pm, when it will just under four degrees above the western horizon. (Held at arm’s length, the first three fingers held together span five degrees.) On Tuesday night at 7:45 pm, the Moon will be a little south of due west and nine degrees above the horizon. Venus will be 16 degrees south (left) of the Moon and only 6 degrees above the horizon. Shining at magnitude -4.5 Venus will obvious.

Sky watchers are familiar with the International Space Station, the largest manned laboratory in orbit and currently home to six astronauts. There is also a Chinese space laboratory, Tiangong 2, in orbit. It hosted a crew of two astronauts from October 19 until November 17, back in 2016, but has been unoccupied since. It is being used to test technologies for a planned Chinese large modular space station.

We see satellites because they are up in bright sunlight when we are in the Earth’s shadow. They look likes stars gliding across the sky. We may see them travel from horizon to horizon, but sometimes a satellite will emerge from the Earth’s shadow and first appear high in the sky, or slide into the Earth’s shadow and vanish when well above the horizon.

Tiangong 2, will pass high over our area on Monday night, appearing brighter than any of the stars in the Big Dipper when high in the sky. Look for it rising up from the western horizon at 8:22 pm. By 8:23 it will be approaching reddish Arcturus, the brightest star in the western sky. Arcturus is the brightest star in Boötes, the Herdsman, a kite shaped pattern of stars stretching above it. Tiangong 2 will pass by Arcturus just after 8:23:30 pm. (This time is given in hours, minutes, and seconds.)

The Chinese space lab will be highest and directly overhead at 8:25 pm and will then move through Cygnus, the Swan, known to some as the Northern Cross. It will then move down toward the eastern horizon and into the Great Square of Pegasus, where it will move into the Earth’s shadow and fade from view, vanishing before 8:27 pm.

There’s another chance to spot Tiangong 2 on Tuesday night. Tuesday’s pass will be a little later and the station will not appear quite as bright, but it will move into the Earth’s shadow and fade from view while high in the sky, which is always fun.

On Tuesday, look for Tiangong 2 coming up from the western horizon at 9:01 pm, passing south (left) of bright Arcturus just before 9:02 pm. Tiangong 2 will pass through Hercules just after 9:03 and will soon fade and vanish as it moves into the Earth’s shadow. How far can you follow it before it vanishes from sight?

Skywatch Line for Friday, September 7 through Sunday, September 9, 2018

This is Dudley Observatory’s Skywatch Line for Friday, September 7 through Sunday, September 9, written by Sam Salem.

On Friday, the Sun rises at 6:27am and sets at 7:20pm; the waning crescent Moon rises at 3:35am and sets at 6:20pm. The new Moon occurs on Sunday at 2:01pm.

Venus, at magnitude –4.7, is the brightest planet in the night sky and is first to set, hitting the horizon roughly one hour after the Sun. Constellation Scorpius lies down in the south-southwest as soon as night arrives. Its brightest star Antares appears about midway between Jupiter and Saturn. Jupiter, at magnitude –1.9, shines well off to Antares’s right, in constellation Libra. Saturn is well off to Antares’s upper left, in constellation Sagittarius. Saturn, at magnitude 0.4, shines more visibly than any star in or around Sagittarius. Saturn culminates almost half an hour after sunset. Mars, at magnitude –2.0, sits on the border between constellations Sagittarius and Capricornus. With the global dust storm now abating, Mars is an interesting target for telescopic inspection. The Martian disk spans about 20 arc seconds and is best placed for observing when Mars reaches the meridian, around 10:30pm. Try catching Mercury at dawn. Currently shining at magnitude –1.1, Mercury rises low in the east-northeast during morning twilight.

On Friday, Neptune reaches opposition. During opposition, as Earth passes between Neptune and the Sun, Neptune rises in the east around the time of sunset, climbing highest up around midnight and setting in the west around sunrise. When a planet outside of Earth’s orbit is at or near opposition, Earth comes closest to that planet, and that planet shines most brightly in our sky. Neptune will be visible all night long and culminates around 1am. Neptune, the eighth planet outward from the Sun, at opposition lies 29 times farther away from Earth than Earth lies from our Sun. Neptune is the only major solar system planet that’s absolutely not visible to the unaided eye. Even at opposition, Neptune is not all that close and it’s not all that bright. Neptune is about five times fainter than the dimmest star that you can see on a very dark night. This moonless weekend is a good opportunity to observe Neptune. As viewed from Earth now, Neptune is in front of constellation Aquarius, the Water Carrier. You’ll need at least binoculars and a sky chart to see Neptune in front of the constellation Aquarius. Find the faint star Lambda Aquarii and Phi Aquarii with the unaided eye and then star-hop to Neptune using binoculars or a telescope.

This weekend try star-hopping to the Andromeda galaxy from the constellation Cassiopeia, the Queen. In a dark sky, you might be able to spot Andromeda galaxy as a hazy patch of light with no optical aid, as the ancient stargazers did. Use binoculars and star-hop to the Andromeda galaxy via the W-shaped constellation, Cassiopeia. Cassiopeia appears low in the northeast sky at nightfall and early evening. It swings upward as evening deepens into late night. In the wee hours after midnight, Cassiopeia is found high over Polaris, the North Star. The deeper V, of the W-shaped Cassiopeia, is the “arrow” in the sky pointing to the Andromeda galaxy. Once you’ve found it with the unaided eye or binoculars, try with a telescope. The Andromeda galaxy is the nearest large spiral galaxy to our Milky Way. It is the most distant celestial object you can see with your eye alone in a moonless, dark sky.

This weekend is one of the prime, moon-free, observing windows for icy comet 21/P Giacobini-Zinner. This is about the first comet readily visible in binoculars this year. The comet is currently located in eastern Auriga and rises around 10:30pm. You get best views of Giacobini-Zinner when it’s highest, in the predawn around 5am. At that hour the comet has an altitude of nearly 60 degrees. For more than two weeks the comet will be the center of attention in a dark sky as it moves from constellations Auriga through Gemini and into Monoceros. The comet is now approaching magnitude 7 as it cruises past the three bright Messier clusters, M38, M36, and M37, in Auriga this weekend. Watch for it to pass close to M37 on Sunday night.