Skywatch Line for Monday and Tuesday, February 18th and 19th, 2019

This is the Skywatch Line for Monday and Tuesday, February 18th and 19th.

The Sun sets at 5:30 PM; night falls at 7:05. Dawn begins at 5:12 AM and ends with Sunrise at 6:47.

The early evening western horizon contains two planet pairs, each with a bright and a dim planet. The first pair occupies Aquarius. Mercury shines with minus 1st magnitude, appears about 80% illuminated, about 6 arc-seconds in size and about 8º above the western horizon. About a half-degree away, much dimmer Neptune shines with 8th magnitude and is a tiny 2 arc-seconds in size. Both set by 6:47 PM. Binoculars are recommended.

The second pair is high due South in Aries. Mars glows with first magnitude, appears about 90% lit and about 5 arc-seconds in size; its distinctive red tint easily identifies it. About 4º to Mars’ upper right is dimmer Uranus, which shines with 5th magnitude and apparently a bit smaller. In telescopes, Uranus sports a blue-green color. Both set by 10:56 PM.

The Moon inhabits Leo on both nights. Monday’s Moon is nearly “full” about 15º above the eastern horizon, rises at 4:24 PM and is best observed at 11:47 PM. Tuesday’s Full Snow Blinding Moon rises at 5:42 PM. This Full Moon is the closest to the Earth for the year – 221,681 miles. Coastal communities can experience very high tides.

Dawn brings three new planets to the scene. First to rise is Jupiter, in Ophiuchus, at 2:45 AM. The giant planet shimmers with minus 2nd magnitude is a large 35 arc-seconds in size and is 18º above the eastern horizon at Dawn.

Constellation Sagittarius houses Saturn and Venus. Saturn is the second to rise at 4:36 AM, shining with zero magnitude and appearing about 5º high. Venus, about 1º from Saturn, rises at 4:34 AM, blazes with minus 4th magnitude, and appears about 70% lit. We have been following Venus’ descent for several weeks, and this is its closest conjunction with Saturn. Both should fit in the same binocular or low power telescope field.

Two comets inhabit our sky, but observations may be degraded by the Full Moon’s brilliance. Comet Wirtanen still occupies the Great Bear’s Head in Ursa Major. It is now fading to 8.5 magnitude. Comet Iwamoto shines with 7th magnitude close to the first magnitude star Castor, in Gemini. Finder charts are available from various online astronomy websites.

The Albany Area Amateur Astronomers hold their monthly meeting on Thursday, February 21st at 7:30 PM. Dr Jennifer Carter, of Union College, will be guest speaker. Her topic will be “The Search for Life.” A few short years ago, such a topic would be considered science fiction. However, recent discoveries made serious such discussions because of numerous exoplanets displaying the potential for having life. Dr. Carter is a Visiting Assistant Professor. She is interested mainly in astrophysics, but also in studying advanced techniques for characterizing and detecting exoplanets. All club events are free and the public is welcome.

Skywatch Line for Friday, February 15 through Sunday, February 17, 2019

This is Dudley Observatory’s Skywatch Line for Friday, February 15 through Sunday, February 17, written by Sam Salem.

On Friday, the Sun rises at 6:53am and sets at 5:27pm; the waxing gibbous Moon rises at 1:00pm and sets at 3:23am. On Friday and Saturday night, watch the Moon pass to the south of the Gemini stars and to the north of star Procyon, brightest star in the constellation Canis Minor. On Friday, Castor and Pollux will reside to the left of the Moon. Procyon is to its lower left, and Orion is to its lower right. On Saturday, right after dark, the gibbous Moon is located between Castor and Pollux to its upper right and Procyon farther to its lower left. By 10 or 11pm this arrangement turns vertical. The waxing gibbous Moon is bright enough to erase many stars from the blackboard of night. But you’ll likely still see the two bright Gemini “twins”, the stars Castor and Pollux in the Moon’s glare.

On Sunday, the Moon’s eastward journey brings it near the Beehive Cluster, M44, in constellation Cancer. Binoculars will show the conjunction. However, its best appreciated in a small telescope used at low power. The waxing gibbous Moon brightness will overpower all but the brightest cluster stars. The best time to look will be around 10pm, when the Moon is nearest M44.

Mars now shines at 1.0-magnitude. It shares the scene with a half dozen stars that are brighter. Thankfully, Mars competes most directly with the relatively dim stars of the autumn constellation Pisces. Mars glows high in the west-southwest at nightfall and sets around 11pm. Venus reigns as the “morning star,” gleaming at magnitude –4.2. It shares the dawn sky with Jupiter, at magnitude –1.9, and Saturn, at magnitude 0.6. Jupiter is first to rise, around 3:00am. Venus rises around 4:30am. Saturn rises around 4:50am. The complete planetary trio is visible until twilight grows overwhelmingly bright.

The Moonlit weekend nights might be a good time for some early season Jupiter observing at dawn. The planet’s appearance can change appreciably in a few months. By observing early in Jupiter’s apparition, you’ll be able to catch everything the planet offers. The more often you look, the better the odds are that you’ll catch a few hours of excellent seeing conditions in which Earth’s atmosphere is calm and details on the planet’s cloud-top surface appear rich with detail. Right now Jupiter climbs to an altitude of roughly 20 degrees as morning twilight brightens. Given the planet’s position in southern constellation Ophiuchus, it doesn’t get much higher than that even when it climbs to the meridian.

Friday marks the 455th. Birthday of Galileo Galilei. The Italian natural philosopher is famously known for applying the new techniques of the scientific method to make significant discoveries in physics and astronomy. Galileo has been called the “father of observational astronomy”, the “father of modern physics”, and the “father of the scientific method”. Galileo studied speed and velocity, gravity and free fall, the principle of relativity, inertia, and projectile motion. He also worked in applied science and technology describing the properties of pendulums and “hydrostatic balances”, inventing the thermoscope and various military compasses. His contributions to observational astronomy include the telescopic confirmation of the phases of Venus, the observation of the four largest satellites of Jupiter, the observation of Saturn and the analysis of sunspots.

Skywatch Line for Wednesday, February 13th, and Thursday, February 14th, 2019

This is the Dudley Observatory Skywatch Line for Wednesday, February 13th, and Thursday, February 14th, written by Louis Suarato.

The 66% illuminated, waxing gibbous Moon sets at 2:29 a.m. Thursday in the constellation Taurus. Before setting, the Moon crosses the sky 4 degrees from Taurus’ brightest star, Aldebaran in the midst of the Hyades star cluster. Aldebaran is the 14th brightest star in the sky. The “eye of the bull” has a diameter slightly larger than our Sun, and is 65 light-years away from our solar system. Look for the Pleiades star cluster about 18 degrees to the west of the Moon. You’ll need binoculars and a clear western horizon to see Mercury as it sets about 40 minutes after sunset. The only easily visible planet during the night is Mars. Mars sets at 10:57 p.m. in Pisces. Use binoculars or a small telescope to find Uranus 1 degree below Mars. Jupiter rises in the southeast at 3 a.m., followed by Venus at 4:30, and Saturn at 4:53. Venus and Saturn will be separated by 4 degrees Thursday morning, and by 3 degrees Friday morning.

In December of 2018, Japanese amateur astronomer Masayuki Iwamoto discovered a comet on its way toward the Sun from beyond the Kuiper Belt. Comet Iwamoto (C/2018 Y1) has a highly elliptical orbit that moves it 5 times further from the Sun than Pluto, taking 1,371 years to complete one orbit. This Wednesday, Comet Iwamoto will make its closest approach to Earth, traveling 0.3 astronomical units, or 27.8 million miles by our planet. Small telescopes or binoculars may be required to see this 6.5 astronomical magnitude comet as it passes close to Earth. If you have a goto telescope, you can use the ephemeris found on for your coordinates. You can also use the constellation Leo as a base for finding the comet. Wednesday night, Comet Iwamoto will be near the head of Leo. The mane of Leo is shaped like a sickle. The last star at the top of the sickle is Algenubi. You’ll find Comet Iwamoto about 7 degrees to the right of Algenubi. You can also use Leo’s brightest star Regulus to locate this comet. Wednesday night, Comet Iwamoto will be about 15 degrees above Regulus. Thursday night, Comet Iwamoto will be a few degrees to the left of M44, the Beehive Cluster.

Skywatch Line for Monday and Tuesday, February 11th and 12th, 2019

This is the Skywatch Line for Monday and Tuesday, February 11th and 12th.

The Sun sets at 5:21 PM; night falls at 6:57. Dawn begins at 5:21 AM and ends with the Sun rising at 6:57.

The 6-day-old Moon dominates the night sky. Monday’s Moon occupies Cetus, appearing about 40% illuminated, about 31 arc-minutes in size and blazes with 9th magnitude. It sets shortly after Midnight. Tuesday’s First Quarter Moon occupies Taurus, is about 50% lit and slightly brighter; it sets shortly after 1 AM.

Mercury makes a brief reappearance in our sky. In Aquarius, it appears about 94% lit, shimmers with minus 1st magnitude, presents a 5.2 arc-second size and lies about 7º above the western horizon. An unobstructed horizon and binoculars are helpful in finding this famously elusive planet. It sets at 6:08 PM.

Neptune, also in Aquarius, glows with 8th magnitude about 12º above Mercury, appears 2 arc-seconds in size and is about 19º above the horizon. It sets at 7:14 PM.

Mars is still the most easily seen planet in the evening sky. In Pisces, it shines with 1st magnitude, appears about 6 arc-seconds in size and is about 90% lit. It sets at 10:58 PM. Uranus, 1 degree next to Mars, forms a nice conjunction with the Red Planet, and that makes it easier to see in the same binocular or finder scope field. In Aries, Uranus shines with 5th magnitude, but is a small 3 arc-seconds in size. Both Mars and Uranus lie about 55º high in the South. However, the brilliant Moon, about 14º away, may hinder seeing Uranus on Monday night. Tuesday evening, the Moon is further away and may make observing this distant planet easier. Uranus sets at 11:00 PM.

Comet 46P/Wirtanen is still inhabits Ursa Major. The comet is near star Theta at 9 PM. Observers continue to report it at about 8th magnitude. Even though it is in far Cetus or Taurus, the Moon may wash out the thin cometary coma and tail. Again, binoculars may help.

Another comet, Iwamoto, is becoming prominent in our skies. Closest to the Sun on February 6th, it races from Virgo to Cancer in a week. On the night of February 10/11, it will be about 1º from a trio of galaxies (M 95, 96, 105) beneath the Lion’s belly. On the night of the 13th, it lies about 3 arc-minutes from NGC 2903, a galaxy at the tip of Leo’s nose. Reports indicate a magnitude between 6th and 7th, within the ability of binoculars and small telescopes.

Dawn brings new players on stage. Jupiter still occupies Ophiuchus, shining with minus 2nd magnitude and a large 35 arc-seconds in size. Rising at 3:08 AM, it lies about 17º high in the East at Dawn.

Venus and Saturn share Sagittarius. Venus rises at 4:29 AM, appearing about 66% lit, blazes with minus 4th magnitude, and appears about 7º high at Dawn. Saturn shines with zero magnitude is about 15 arc-seconds in size and is about 3º high at Dawn, but is 12º altitude at Civil Dawn. Saturn rises at 5:01 AM. Notice the distance between Venus and Saturn. Venus is gradually becoming lower daily. At Civil Dawn, they are separated by about 6º. About a week from now, they will be about 1º from each other.

Polaris, the Pole or North Star, is one of the most famous of all stars. Many people think that it is the brightest; it is not, only second magnitude. Its importance is an accident of place; Polaris happens to occupy the spot closest to true North. In a few thousand years, it will drift away, and another star will become the Pole Star. Many do not know that it is a multiple star system. Using the Hubble Telescope, astronomers recently discovered a third member. By analyzing the stars’ orbits, they “weighed” Polaris, and found it about four times heavier than our own Sun. Polaris has one distinction. Not many people know that it is a variable star; it periodically brightens and dims. Polaris is a Cepheid variable; in fact, it is the brightest of its kind in our sky. Cepheids are valuable stars. The period of their variation is in direct ratio to their brightness. So, if an observer sees a Cepheid and tracks its cycles, he can determine its intrinsic brilliance and also derive its distance from us.

Skywatch Line for Friday, February 8 through Sunday, February 10, 2019

This is Dudley Observatory’s Skywatch Line for Friday, February 8 through Sunday, February 10, written by Sam Salem.

On Friday, the Sun rises at 7:03am and sets at 5:18pm; the waxing crescent Moon rises at 9:05am and sets at 9:00pm. On Sunday evening the crescent Moon is situated roughly six degrees to the left of Mars, high in the west-southwest as twilight fades. Use the Moon to find Mars, which shines as brilliantly as a 1st-magnitude star. Let bright Mars guide you to the faint planet Uranus. Chances are that you won’t spot Uranus with the eye alone. If you have binoculars, aim them at Mars to glimpse at Uranus and Mars in the same binocular field together. Don’t mistake the star Omicron Piscium for Uranus. The star is brighter than Uranus. It makes a nice triangle with Mars and Uranus in a single binocular field. Mars remains in close vicinity of Uranus this upcoming week, giving you an opportunity to use Mars to zoom in on Uranus with binoculars. On Sunday at nightfall, the Moon pretty much makes a straight line with the star Omicron Piscium and Mars, with Omicron Piscium in between the Moon and Mars.

Uranus is arguably the most mysterious planet in the solar system. The ice giant is spinning on its side. Unlike all the other planets, which spin roughly “upright” with their spin axes at close to right angles to their orbits around the Sun, Uranus is tilted by almost a right angle. In Uranus’ summer, its north pole points almost directly towards the Sun. Unlike Saturn, Jupiter, and Neptune, which have horizontal sets of rings around them, Uranus has vertical rings and moons that orbit around its tilted equator. The ice giant also has a surprisingly cold temperature and a messy and off-center magnetic field. Scientists suspect that Uranus was once similar to the other planets in the solar system but was suddenly flipped over. Most researchers believe that Uranus’ spin is the consequence of a dramatic collision. A new research, published in the Astrophysical Journal last year, ran computer models simulating solar system formation events, using a powerful supercomputer, to offer some clues of how Uranus’ mysterious spin could have happened. Another important motivation of the research is to learn about evolution of ice giants to help our understanding of their distant cousin, exo-planets.

Mars, at 0.9-magnitude, is still the lone evening planet. It’s nicely placed at dusk and sets around 11:00pm. At dawn, a trio of planets is arrayed across the southeast. First up, is magnitude –1.9 Jupiter, rising around 3:20am. An hour later, Venus gleaming at magnitude -4.3, reigns as the “morning star”. Last to appear is the magnitude 0.6 Saturn. Still at the very beginning of its apparition, Saturn clears the southeast horizon just before the start of morning twilight, at about 5:15am. Viewing conditions will steadily improve for Jupiter and Saturn as they climb slightly higher each morning, but Venus is gradually losing altitude as it sinks toward its August conjunction with the Sun.

This weekend as the Moon sets around 10pm, the prime winter constellations sit near the meridian. Constellation Canis Major is home of the lovely open cluster M41. The cluster is easy to find. First, locate the brightest star in the night sky, Sirius, or the Dog Star. Sirius gleams brilliantly at magnitude –1.4. Center Sirius in your binoculars or telescope. Then, dip four degrees south to bring M41 into view. If all the cluster members were gathered together in a single point, M41 would shine with the brightness of a 4th magnitude star. The stellar grouping should be dimly visible without optical aid under a dark, country sky. The cluster stands out reasonably well in binoculars even under a moderately light-polluted sky, and it’s a lovely sight in a small scope used with modest magnification. M41 is roughly the same apparent size as the Moon. Too much power spoils the view by narrowing the telescopic field.

Skywatch Line for Wednesday, January 6th, and Thursday, January 7th, 2019

This is the Dudley Observatory Skywatch Line for Wednesday, January 6th, and Thursday, January 7th, written by Louis Suarato.

The 4% illuminated, waxing crescent Moon sets at 7:03 Wednesday night. Mars will be found in the constellation Pisces to the Moon’s upper left. Look over the southeastern horizon after 5:30 a.m. to see the sweeping curve formed by three planets and a bright star. The three planets, from top down the horizon, are Jupiter, Venus, and Saturn. To the right of Jupiter is Scorpius’ brightest star, Antares. The word Antares is derived from the ancient Greek, meaning “rival to Mars”. The star was named for its similarity in color to reddish Mars. Antares is a red super-giant star located about 604 light-years away from the Sun, and is 700 times the Sun’s diameter.  If placed in our solar system, Antares would stretch out to the orbit of Mars. Antares is one of the top 10 largest stars in the galaxy.

You may not know it from the multitude of cloudy nights we’ve had, but winter is the best for observing. When the clouds have cleared, the winter nights become clearer because the cold air has less capacity to hold moisture, eliminating most of the haziness. During any season, the higher your observational targets are above the horizon and its atmosphere, the more improved is the seeing. There are several web and phone apps to assist you with determining the forecasted sky quality. “Clear Sky Chart” is a free phone application that contains many local observing sites, including the Landes Arboretum, Grafton Lakes State Park, and Dudley Observatory in Schectady. The on-line version of this application can be found at Another phone app that provides weather forecasts, seeing, transparency, and light pollution is “Good To Stargaze”. The free version of this app displays a 24 hour forecast, A version providing a 7 day forecast can be obtained with an annual subscription fee.

Skywatch Line for Monday and Tuesday, February 4th and 5th, 2019

This is the Skywatch Line for Monday and Tuesday, February 4th and 5th.

The Sun sets at 5:12 PM, night falls at 6:49. Dawn begins at 5:29 AM and ends with the Sun rising at 7:05.

Mars is the only easily visible planet in the evening sky and will remain so for the month. In Pisces, it shines with 1st magnitude, appears about 90% illuminated and is about 55º high at Civil Dusk. It sets at 11:01 PM. Mars shares Pisces with Uranus, about 5º to Mars’ upper left; both should fit within the same binocular and finder scope view. Uranus glows with 5th magnitude and appears about 3 arc-seconds of size in your instrument. It sets at 11:27 PM.

Neptune, in Aquarius, is far to Mars’ lower right, sparkling with 8th magnitude, a tiny 2 arc-seconds in size and about 24º above the western horizon.

The Moon turns New at 4:40 PM Monday, which means that it is totally absent from Monday and Tuesday nights. This presents an opportunity for hardy astronomers to take in the wonders of the winter sky. The 1-day-old Moon makes a brief appearance on Tuesday; it twinkles with 3rd magnitude and is a slim 1% lit only 2º above the western horizon, where it sets at 6:02 PM.

One of those wonders is the comet Wirtanen, which still occupies the Great Bear’s head, ahead of the two stars that forms the Big Dipper’s front. The Comet is circumpolar, which means it does not rise or set. Comet Wirtanen continues to pull away from Earth, which means it is now about 8th magnitude and slowly fading.

Finder charts for Uranus, Neptune and Wirtanen are available from various online astronomical websites.

The pre-dawn sky contains the brightest planets. Jupiter is the first to rise at 3:30 AM in Ophiuchus. It glimmers with minus 2nd magnitude, appears about 34 arc-seconds in size and is about 15º high at Civil Dawn.

Venus, about 13º to Jupiter’s lower left, blazes with minus 4th magnitude in Sagittarius, appearing about 64% lit and 9º above the eastern horizon; it rises at 4:21 AM.  This month, Venus dims and shrinks slightly, but becomes a fatter crescent in our telescopes and binoculars.

Saturn, also about 13º to Venus’ lower left, brings up the rear, in Sagittarius, glowing with zero magnitude but a moderate 15 arc-seconds in size. It rises at 5:25 AM and can be seen about 10º above the eastern horizon before Sunrise.

The past months saw the US as the victim of several winter storms. As bad as these storms were, they are small compared to storms on other solar system members. The most famous example is the Great Red Spot on Jupiter. This tempest has been continuously observed for three hundred years, and is probably older. The Great Red Spot is actually a high-pressure hurricane, larger than the Earth. Jupiter experiences ordinary thunderstorms that radio amateurs can pick up on their ham radios. Saturn also periodically displays cyclones. In 2010, amateur astronomers discovered the Great White Spot, a thunderstorm over 100 times larger than earthly ones. Uranus displayed an outburst, with 500 miles-per-hour winds, that lasted five years. Mars periodically experiences planet-wide dust storms; last year, such a flare-up prevented astronomers from observing Mars when it was extremely close to Earth. The same event finally silenced the rover Opportunity; apparently, the dust was so thick and persistent that its solar panels could not recharge its batteries and heating. Neptune also periodically displays severe weather. Finally, our Sun is constantly flaring and sending out clouds of charged particles. Major corporations and governments retain solar scientists to predict Space Weather, so that satellites, communications and astronauts are protected.

Skywatch Line for Friday, February 1 through Sunday, February 3, 2019

This is Dudley Observatory’s Skywatch Line for Friday, February 1 through Sunday, February 3, written by Sam Salem.

On Friday, the Sun rises at 7:11am and sets at 5:09pm; the waning crescent Moon rises at 4:56am and sets at 2:23pm. Before dawn on Saturday, Moon, Saturn, Venus, and Jupiter form a line in the East.  See if you can catch the slender waning crescent Moon near Saturn. Saturn and the lunar crescent will be low in the east-southeast in bright twilight. The ringed planet is fainter than Jupiter and Venus.  Try using Venus and Jupiter as guides. A line between these two bright planets will point to the Moon and Saturn near the sunrise point on the horizon.  Although Saturn is as bright as a 1st-magnitude star, it will appear tarnished by the early morning twilight. If you can spot the thin crescent Moon, but not Saturn, binoculars might help you glimpse nearby Saturn in the glow of dawn.

At dusk, see Mars shining at magnitude 0.9 among the dim stars of constellation Pisces. The red planet is now well west of the meridian at sunset, and as darkness falls it has an altitude of around 45 degrees.  A trio of planets is arrayed across the southeast at dawn.  Jupiter, at magnitude –1.9, rises at roughly 3:45am. Half an hour later, brilliant Venus, at magnitude –4.3, pops up. Last to appear is Saturn, which clears the east-southeast horizon around 5:40am. The 0.6-magnitude ringed planet is just beginning its apparition and will be visible in the evening sky in late spring.

This moon-free weekend is prefect for some deep-sky observing. Try star-hopping to the famous Andromeda galaxy, the large spiral galaxy next-door to our Milky Way, from the Great Square of Pegasus.  Look westward for the four stars of the Great Square. You’ll find them high in the west at early evening. The Great Square will sink toward the west-northwest horizon as evening deepens, but this famous pattern of stars will remain in view until mid-to-late evening.  Focus on the top star of the Great Square you’ll see the constellation Andromeda as two streamers of stars jutting up from uppermost Great Square star. Go to the second star upward on each streamer, Mirach and Mu Andromedae. Draw an imaginary line from Mirach through Mu, going twice the Mirach/Mu distance to get to the Andromeda galaxy. On a dark night, the Andromeda galaxy looks like a faint, blurry patch of light. You can see it with the unaided eye if your sky is dark enough.  Andromeda is an easy binocular find and magnificent in a low-power telescope.

Next, head northeast to take in the Double Cluster, almost directly overhead, in constellation Perseus. The Double Cluster consists of two open star clusters, known as “H” and “Chi” Persei.  They are also called NGC 884 and 869.  This is a terrific target and lovely in a small, wide-field scope. Just above Cassiopeia you’ll see a faint fuzzy patch. This is the Double Cluster.  It blooms into a sparkling array of stars through binoculars or a small backyard telescope.

Skywatch line for Wednesday, January 30th, and Thursday, January 31st, 2019

This is the Dudley Observatory Skywatch line for Wednesday, January 30th, and Thursday, January 31st, written by Louis Suarato.

Begin your Wednesday by looking above the Southeast horizon about two hours before sunrise. The 25% illuminated, waning crescent Moon sets the stage by rising around 3 am. The Moon is joined by Jupiter 45 minutes later. One half hour later, Venus joins the Moon and Jupiter. By 5:30 am, the three are high above the southeastern horizon, forming a swooping downward curve. You may require binoculars to see Saturn by the time the ringed planet rises at 5:46, about an hour and half before sunrise. The crescent Moon and two bright planets perform an encore Thursday morning, when Jupiter shines 3 degrees to the upper right of the Moon and Venus. The thinner crescent Moon and Venus will be separated by 2 degrees. Weather permitting, each day should provide excellent photo opportunities.

On these mornings, use your binoculars to observe the star cluster, M23, located 4 degrees to the right of Venus. Discovered by Charles Messier on June 20, 1764, M23, or also known as NGC 6494, is an open star cluster in the constellation Sagittarius. This star cluster is 2,050 light-years away, consisting of approximately 400 stars, and estimated to be 330 million years old. Open star clusters are made up of up to a few thousand stars that were formed by the same molecular cloud. And are loosely gravitationally bound. More than 1,100 open star clusters have been discovered within the Milky Way Galaxy.

If you thought a day on Saturn was 10 hours, 39 minutes, and 23 seconds, well, there’s been an update, thanks to the Cassini spacecraft. A day on any planet is measured by how long it takes to complete a full rotation on its axis in Earth hours, minutes, and seconds. As we know, an Earth day, on average, takes 24 hours. Mercury rotates once every 58.646 Earth days. Venus rotates once every 243.025 Earth days. A day on Mars takes 24 hours, 37 minutes, and 22 seconds. Jupiter, with its high velocity rotational rate of 28,148.115 miles per hour at its equator, completes its day in 9 hours, 55 minutes, and 30 seconds. Uranus completes one turn on its axis every 17 hours, 14 minutes, and 24 seconds. But since Uranus’ axial tilt is 97.77 degrees, causing it to orbit the Sun on its side, with either pole toward Sun, this planet has 42 years of sunlight aimed at each pole during its orbit. Before the Cassini spacecraft successfully completed its maneuvers through Saturn’s rings, it was difficult to precisely determine the length of its day given the lack of identifiable features at it cloud tops. Cassini was able to identify distinguishable vibrations in the rings caused by the planet’s gravitational waves. With this new data, Cassini helped determine that a day on Saturn is actually 10 hours, 33 minutes, and 38 seconds.

Skywatch Line for Monday and Tuesday, January 28th and 29th, 2019

This is the Skywatch Line for Monday and Tuesday, January 28th and 29th.

The Sun sets at 5:03 PM; night falls at 6:40. Dawn begins at 5:35 AM and ends with the Sun rising at 7:31.

Mars remains as the sole bright planet in the evening sky. In Pisces, it rose during daytime and, by civil dusk, appears about 89% lit, shines with zero magnitude and is about 54º high in the southwestern sky. The Red Planet sets at 11:04 PM. Uranus shares Pisces with Mars, but sits about 10º to Mars’ upper left, shines with 5th magnitude, appears smaller about 57º high and sets at 11:53 PM.

Neptune, in Aquarius, is dimmer with 8th magnitude and is a tiny 2.2 arcs-seconds in size. It appears about 29º high and sets at 8:06 PM.

Comet 46P/Wirtanen is still visible in Ursa Major, The Big Bear. It appears in the Bear’s Head, in front of the Dipper’s front two stars. It has been observed with 7th magnitude.

Finder charts for Neptune, Uranus and Wirtanen are available from online astronomical websites.

Tuesday’s Moon rises in Libra at 1:58 AM, appearing about 33% lit, blazing with minus 11th magnitude and about 30º high. Wednesday, the Moon migrates to Ophiuchus, rises at 3:01 AM, is about 24% illuminated and about 25º high in the East. The Moon has attracted headlines around the world. During last Monday’s Total Lunar Eclipse, many people claimed to witness a bright flash on the Moon’s eclipsed side. Amateur and professional video from around the world substantiated those claims. Asteroids hit the Moon all the time, but are rarely witnessed. Lunar scientists estimate it crashed near the crater Byrgius. If you watched the eclipse, you may have seen it, if you didn’t blink at the critical time. NASA has a satellite orbiting the Moon, photographing its surface. They hope to find and publish pictures of this fresh crater.

Jupiter, in Ophiuchus, rises at 3:52 AM. It shines with minus 2nd magnitude and appears a large 33 arc-seconds size. At Civil Dawn, it’s found about 21º above the eastern horizon. Venus, also in Ophiuchus, lies about 6º below Jupiter. Venus appears about 61% lit and blazes with minus 4th magnitude, appears about 20 arc-seconds in size and is 19º high at Civil Dawn. Saturn, 21º below Venus, rises in Sagittarius at 5:50 AM and is about 7º high, still too low for good views of the Ringed Planet. Riding high in the South about 9:00 PM is the object astronomers call M45, but is commonly called the Pleiades.  The Pleiades form a mini dipper that is so distinctive that virtually all cultures have named and worshiped it.  Many peoples used it as a farming calendar.  When the Pleiades rise in the Fall, it is time to harvest.  When it sets in the Spring, it is planting time.  Ancient Greeks called it the “Seven Sisters”, and other societies had similar names, giving rise to the legend of the “Lost Pleiad”.  One of the stars has apparently dimmed in the past, because, today, most people can see only six stars without any optical aid.  Most likely, the star known as Pleione was brighter in ancient times and had recently dimmed.