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.

Skywatch Line for Friday, January 25 through Sunday, January 27, 2019

This is Dudley Observatory’s Skywatch Line for Friday, January 25 through Sunday, January 27, written by Sam Salem.

On Friday, the Sun rises at 7:17am and sets at 4:59pm; the waning gibbous Moon rises at 10:38pm and sets at 10:16am. The Moon reaches last quarter phase at 4:10pm on Sunday, however, it doesn’t rise until after 1am on Monday.

Mars, at magnitude 0.8, hovers in the south-southwest in the evening. The sole evening planet is still a conspicuous sight amid the faint stars of constellation Pisces. Mars sets around 11pm. Venus and Jupiter rise a few minutes after 4am. Venus has been steadily losing altitude while Jupiter has been gaining. The two planets pass in the dawn as the magnitude –4.4 Venus slowly slips by the magnitude –1.8 Jupiter. If you have an unobstructed east-southeast horizon, try to find Saturn using binoculars. It’s just now slowly emerging from its January 2nd. solar conjunction. Saturn shines at magnitude 0.5, and rises roughly one hour before the Sun.

Winter constellations are climbing higher in the early evening as the end of January nears. Evenings over the weekend are moon-free, allowing for some winter deep-sky hunting. One of the season’s most recognizable shapes is the distinct W of Cassiopeia, now high overhead. Cassiopeia is home to two Messier clusters, M52 and M103, as well as several rich NGC clusters. You can spend a rewarding hour or two with a small telescope exploring the stellar swarms located just between the stars Delta (δ) and Epsilon (ε) Cassiopeiae. Begin your hunt with M103, which is found just one degree northeast of 2.6-magnitude star Delta. M103 glows at magnitude 7.4. You can easily see it with binoculars. M103 is a tight knot of stars that features a few standout members brighter than magnitude 8. From M103, it’s a short hop northeast to NGC663, the region’s other bright open cluster. NGC 663, also known as Caldwell 10, is a young open cluster of about 400 stars in the Cassiopeia constellation. It spans about a quarter of a degree across the sky. It can reportedly be detected with the unaided eye. It looks conspicuous in binoculars as the brightest members of the cluster can be viewed.

M 52 is another bright open cluster located in constellation Cassiopeia. Messier 52 can easily be seen with binoculars. In 10×50 binoculars, it appears as a hazy, nebulous patch of light. 4-inch telescopes reveal a dense, compressed star cluster populated by many faint stars, with a shape resembling that of the letter V. More stars are visible in 6-inch and larger instruments. The cluster occupies an area just less than half of the size of the full Moon. M 52 is very easy to find as it lies near Cassiopeia‘s prominent W asterism. The cluster can be located by extending the line from the stars Schedar (Alpha Cassiopeiae) to Caph (Beta Cassiopeiae) to the northwest, about the same distance as that between the two stars. Messier 52 lies near another prominent deep sky object, the Bubble Nebula (NGC 7635). The nebula can be seen about 35 arc-minutes southwest of the cluster.

Skywatch Line for Wednesday, January 23rd, and Thursday, January 24th, 2019

This is the Dudley Observatory Skywatch Line for Wednesday, January 23rd, and Thursday, January 24th, written by Louis Suarato.

The 89% illuminated, waning gibbous Moon rises at 8:04 Wednesday night below the constellation Leo. Thursday night, the Moon will make its trip across the sky in Virgo. The constellation Leo has been identified as a lion by many ancient civilizations, including the Mesopotamians, Perians, Turks, Syrians, Hebrews, and Indians. This easily distinguishable constellation can be found by following the pointer stars of the Big Dipper in the opposite direction of Polaris, the North Star. The cycle of stars forming the lion’s mane are Algenubi, Kasalas, and Adhafera. The end of the Lion is marked by the star Denebola, which means “lion’s tail”.  

Mars remains the only easily visible planet in the nighttime sky. Look for Mars in Pisces before it sets at 11:06 p.m.. The pre-dawn sky continues to be dominated by the planets Venus and Jupiter, which are 3 degrees apart. Look over the southeastern sky after 5 a.m. for these bright, closely paired planets.  Venus and Jupiter will move apart as Venus travels closer toward the Sun. Saturn joins Venus and Jupiter, as it makes its reappearance in the morning sky. If you have a clear southeastern horizon, you may be able to see Saturn after 6:07 a.m. and before it’s lost in the glow of sunrise.

On January 24, 1986, the spacecraft Voyager II made its closest approach to the planet Uranus. Traveling as close as 50,600 miles above the planet, Voyager II transmitted thousands of images back to Earth. Among its discoveries, Voyager II sent images of 10 previously unknown moons, and 2 never before seen rings. Launched by NASA on August 20, 1977, Voyager II is currently travelling toward interstellar space, having traveled 9.5 billion miles.

Skywatch Line for Monday and Tuesday, January 21st and 22nd, 2019

This is the Skywatch Line for Monday and Tuesday, January 21st and 22nd.

The Sun sets at 4:54 PM; night falls at 6:33. Dawn begins at 5:40 AM and ends with the Sun rising at 7:19.

Mars is the only naked-eye visible planet in the evening. The Red Planet shines with zero magnitude in Pisces, appears about 89% illuminated, is 6.5 arc-seconds in size, and about 51º high in the South. Mars sets at 11:07 PM. Uranus shares Pisces with Mars, but is about 14º to Mars’ upper left. Uranus shines with 6th magnitude and is seen with 3.5 arc-seconds in size. Uranus is best observed at 5:38 PM and sets at 12:20 AM.

Neptune, about 30º below Mars in Aquarius, glimmers with 8th magnitude and is a tiny 2.2 arc-seconds in our telescopes. Neptune sets at 8:33 PM.

Nightfall sees the post-eclipse Moon rising in Cancer at 5:39 PM. The nearly full Moon blazes with minus 12th magnitude and is about 8º high in the East. It is best observed at 1:08 AM, Tuesday and sets during daytime. Tuesday’s Moon rises in Leo at 6:55 PM, appearing about 94% lit and 20º high. It is best observed at 2:08 AM, Wednesday and also sets during daytime.

Despite the blazing Monday Moon, Comet Wirtanen is still visible. It currently occupies the Great Bear’s head and is reported to be about 6th magnitude, visible to naked-eye viewers in dark rural skies.

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

Bright planets blaze in the pre-dawn sky. Venus, rising in Ophiuchus at 4:03 AM, appears abut 58% lit, 21 arc-seconds in size and at magnitude minus 4. About 2.4º below Venus, lies Jupiter, also in Ophiuchus. It shimmers with minus 1st magnitude, rises at 4:14 AM and a large 33 arc-seconds in size.  Note their positions; last week they were further apart, and will, later this month, appear very close to each other. Jupiter also lies about 8º from the red giant star Antares.

Finally, Saturn, in Sagittarius, rises at 6:15 AM, about 28º below the Venus-Jupiter pair but 5º above the horizon. Saturn shines with zero magnitude. Again, note its position. Saturn, too, in on the move and approaches a sinking Venus.

With Venus so prominent in the pre-dawn sky, let us examine her in detail. Venus is the second planet from the Sun. It is almost an Earth twin, about the same size and slightly less mass. Early telescopic observers noted its complete cloud cover. They speculated that Venus was a lush, tropical planet. As science obtained better instruments, rude shocks came. Venus did not rotate in 24 hours like Earth; its day lasts 243 earth-days. Russian and US probes landed on Venus; pictures showed a rock filled wasteland. Those same probes recorded a toxic atmosphere with true acid rain. Since Venus is closer to the Sun, it gets twice the solar radiation. Temperatures approach the melting point of lead and atmospheric pressure is 90 times that of Earth. Its slow rotation and lack of axis tilt means no seasons or weather. Most planetary scientists now think that Venus is a case of uncontrolled global warming. Any oceans boiled off, leaving an atmosphere of 96 percent carbon dioxide. Without oceans, there was no water to capture the carbon dioxide into limestone rocks, as on Earth.

Skywatch Line for Friday, January 18 through Sunday, January 20, 2019

This is Dudley Observatory’s Skywatch Line for Friday, January 18 through Sunday, January 20, written by Sam Salem.

On Friday, the Sun rises at 7:22am and sets at 4:50pm; the waxing gibbous Moon rises at 2:22pm and sets at 4:36am.

Mars, at magnitude 0.7, continues to have the evening sky all to itself as the lone planet, outshining the stars nearby. Its distinctive color makes Mars easy to spot, slightly west of due south at dusk. Venus, at magnitude –4.5, rises around 4am. In a telescope with enough magnification, all one generally sees is a snow-white disk exhibiting a moonlike phase. Not far behind Venus is Jupiter, which clears the southeast horizon a little more than half an hour later. Jupiter shines at magnitude –1.8 and attains an altitude of 15 degrees in bright morning twilight. Jupiter offers lots of detail in a telescope, but only when it climbs higher. It will be several more weeks before we can productively turn our telescopes on Jupiter once again.

This weekend has the year’s first full Moon, first lunar eclipse, and first supermoon. Full Moon occurs Sunday night at 12:16am. Lunar eclipse occurs when Moon is full. Yet, a lunar eclipse doesn’t happen at every full Moon. The reason is that Moon swings anywhere from five degrees north or south of the Earth’s shadow. Lunar Eclipse occurs when the Moon is directly opposite the Sun in Earth’s sky. Examine the Moon during eclipse as it appears larger than normal. Perigee, when the Moon is closest to the Earth, occurs only about 14 hours after maximum eclipse. A full Moon that comes within 90% of its closest approach to Earth is defined as a supermoon.

The total eclipse of the Moon lasts for somewhat more than one hour, and is preceded and followed by a partial umbral eclipse, each time persisting for over an hour. The whole umbral eclipse from start to finish has a duration of nearly 3-1/3 hours. The total eclipse and can be viewed from North and South America, Greenland, Iceland, Europe, northern and western Africa plus the Arctic region of the globe. A penumbral lunar eclipse takes place before and after the umbral lunar eclipse. A penumbral lunar eclipse is so faint that many people won’t even notice it while it is happening. The lunar disk often exhibits a coppery color during a total lunar eclipse. Although the Moon is completely immersed in the Earth’s dark shadow, the Earth’s atmosphere refracts sunlight and the longer wavelengths of light, red and orange, pass onward to fall on the Moon’s face.

Binoculars make eclipse colors more vivid and give 3D views of the eclipsed Moon suspended among the stars. A telescope will reveal subtle colors in Earth’s shadow as well as “mini-eclipses” of craters and other lunar features as the gradually advancing shadow covers them one after another. Also notice that the shadow is curved. That was the clue ancient observers used to deduce that Earth must be spherical.

The lunar eclipse runs from 9:36pm on Sunday night to 2:48am. The penumbral eclipse begins at 9:36pm. The partial eclipse begins at 10:33pm, when the Moon enters umbra. The full eclipse begins at 11:41pm. The Moon is deepest in umbral shadow, mid-eclipse, at 12:12am. Full eclipse ends at 12:43am, when the Moon starts to leave umbra. Partial eclipse ends at 1:50pm, when Moon exits umbra. Penumbral eclipse ends at 2:48am, when Moon exits penumbra.
For more information on the Supermoon Lunar Eclipse visit the link below.
The Dudley Observatory is organizing a Lunar Eclipse party on Sunday night at miSci. The party includes Planetarium shows, Lunar Eclipse viewing (weather permitting), viewing through their antique 19th century Comet Seeker telescope (rain or shine), live streaming of the eclipse indoor, food coffee and hot chocolate, and a variety of other activities. The Party runs from 9pm to 2am.
For more information and pre-registration, visit the link below.