Category Archives: Skywatch Line

This is Dudley Observatory’s Skywatch Line for Friday, July 10, through Sunday, July 12, written by Sam Salem.

On Friday, Sun rises at 5:27am and sets at 8:34pm; Moon sets at 10:52am. On Sunday, the Moon will reach its last quarter phase at 7:29pm. At last quarter, the Moon rises around midnight (Standard Time) and remains visible in the southern sky during morning daylight.

In the southeastern sky during the hours before dawn on Saturday, the Moon will shine near Mars. Look for the waning gibbous Moon positioned a palm’s width of the bright, red planet. As the pair crosses the sky together, the Moon’s orbital motion will carry it noticeably closer to Mars by dawn. The same movement will cause the Moon to hop to the left-hand, or eastern side, of Mars on Sunday morning. Mars, at magnitude -0.6, rises due east around 1am, shining at the border of constellations Pisces and Cetus. In a telescope Mars has grown to 12 arc-seconds in apparent diameter. Mars will grow to 22.6 arc-seconds wide when it passes closest by Earth around opposition in the first half of October.

Venus will reach -4.47 magnitude for the current morning apparition, in the early hours of Friday. In a telescope, the planet will show a 27 percent illuminated waxing crescent phase and an apparent disk size of 37 arc-seconds. Even with a less than fully-illuminated disk, Venus’ nearness to Earth will boost its brightness. After rising at about 3am, the extremely bright planet will be visible in the eastern pre-dawn sky, just above the bright orange star Aldebaran in constellation Taurus. Venus’ trip through the triangular face of Taurus, the Bull will be concluding on Sunday, when the bright planet passes less than a finger’s width to the upper left of Aldebaran. Look for the star and planet sitting above the eastern horizon together for about two hours before dawn. Look 12 degrees up to see the Pleiades.

The Moon passes 4 degrees south of Neptune at 3am, on Friday. At that time, the planet is nearly 30 degrees high in the southeast, hanging against the stars of Aquarius. The magnitude 7.9 ice giant is an ideal binocular object this month, although the bright nearby Moon may make it a bit of a challenge to pick out this Friday morning. Swing about 16.5 degrees due east of Neptune to spot Mars, which will be much easier to find. The magnitude 5.8 Uranus, in constellation Aries, is up in the east just before dawn, about midway between Venus and Mars.

Jupiter and Saturn rise in twilight, loom low in the southeast after dark, and climb as the evening grows late. Saturn is about 6 degrees to Jupiter’s lower left. Farther to Jupiter’s right is the Sagittarius Teapot. The two planets are highest around 1am.

This is the Dudley Observatory Skywatch Line for Wednesday, July 8th, and Thursday, July 9th, written by Louis Suarato.

The 92% illuminated, waning gibbous Moon rises at 11:13 p.m., Wednesday. Jupiter rises in Sagittarius at 8:48 p.m., followed by Saturn at 9:09 p.m. seven degrees away. Jupiter’s moon Callisto’s shadow begins to transit the planet at 2:33 a.m., followed by Callisto an hour and seven minutes later. Friday, the shadow of Jupiter’s largest moon, Ganymede, begins its transit at 2:31 a.m., followed by Ganymede 21 minutes later.

About 45 degrees to Saturn’s southeast, globular cluster M2 rises with the gas giants. By 1:30 a.m., M2 will be above and to the right of the Moon, about 40 degrees above the southeastern horizon. Discovered by Jean-Dominique Maraldi in 1746, M2 is one of the largest, and oldest, known globular clusters with an estimated diameter of 175 light-years wide. It is approximately 55,000 light-years away, and 13 billion years old. M2 contains about 50,000 stars, and can be seen with binoculars or small telescopes. Look 5 degrees north above the star Beta Aquarii for M2. Mars rises 15 minutes after midnight in the constellation Pisces. Venus rises at 3:07 a.m., about 1 degree above Taurus’ brightest star, Aldebaran.

While Venus is rising, look about 40 degrees to its lower left, below the bright star Capella, for Comet C/2020 F3 (NEOWISE). Comet Neowise has survived its trek around the Sun, and its closest approach on July3 at a distance of 27.3 million miles, and is on the return trip of its 4,500 to 6,800 year orbit. Discovered by the NEOWISE space telescope on March 27, 2020, Comet Neowise is estimated to be 0.8 magnitude and naked eye visible, but you’ll need a clear horizon to see it before the glow of dawn washes it out.

This is the Skywatch Line for Monday and Tuesday July 6th and 7th.

The Sun sets at 8:36 PM; night falls at 10:49. Dawn breaks at 3:12 AM and ends with the Sun rising at 5:25.

The Moon occupies Capricornus on both nights. Monday’s Moon, one day after Full Moon, appears 96% lit, rises at 10:07 PM and sets at 7:41 AM, Tuesday. Tuesday’s Moon appears only a little thinner and slimmer, rising at 10:47 and setting at 8:07 AM.

Jupiter shares Sagittarius with Pluto and Saturn. Jupiter rises at 9 PM and appears about 16° high in the south eastern sky. This month, Jupiter is at its largest and full of telescopic detail. Observers now describe the Great Red Spot as closer to pink-red. The Great Red Spot will appear centered on Jupiter’s face at 2:50 AM on Tuesday. Tuesday night also affords views of the Jovian moon Io casting its shadow on Jupiter at 1:36 AM, beginning its transit at 1:47 AM and ending its trek at 3:53 AM. At 1:14 AM on Wednesday, Io reappears from behind the giant planet. Pluto rises 6 minutes after Jupiter, is preparing for a June 30th conjunction with Jupiter; it glows dimly with 14th magnitude, appears less than an arc-second in size and lies within 1 arc-second from Jupiter. Pluto hunters need at least an 8-inch telescope, dark skies and detailed star charts.

Saturn rises about 20 minutes after Jupiter. It shines with zero magnitude, is 18 arc-seconds in size; it will remain the same for a couple of weeks. Its rings span 42 arc-seconds, providing dramatic telescopic views. The Moon accompanies Saturn on both nights, about 10° below Saturn on Monday and 23° aside on Tuesday.

Both Jupiter and Saturn appear to follow each other, but actually they are slowly separating from 6° to 7° at month’s end. They are also retrograding – traveling westward.

Mars rises in Pisces at 12:23 AM, shines with minus 0.6 magnitude, larger with 11.2 arc-seconds in size. This month it grows brighter and larger in our instruments in preparation for its October close approach to Earth; Mars begins this month 76 million miles from Earth and ends only 60 million miles away.

Neptune rises in Aquarius at 11:38 PM glows with 8th magnitude and appears 2 arc-seconds. Uranus rises in Aries at 1:32 AM, brighter at 6th magnitude and about 4 arc-seconds in size.

Venus is the last to rise in Taurus at 3:15 AM, blazes with minus 4th magnitude, 39 arc-seconds, but only about 7° high in the East. Note that Venus appears close to Aldebaran, the brightest star in the constellation; this month Venus climbs higher in the pre-dawn sky.

As appropriate for the upcoming racing season, two horses appear by midnight. The largest horse is, of course, Pegasus. The smallest is Equuleus. This dim constellation is easy to find. Pegasus flies upside down and is easily identified as a Great Square. Two thin chains sweep northward from the upper left. If one sweeps across the chain, binoculars reveal a large hazy oval; this is revealed, in telescopes, to be the Andromeda Galaxy – about two and a half million light years distant. You can see it with the naked eye under rural skies. Pegasus’ neck flows from the lower right corner and angles up. Equuleus is the small angular line of stars West of the Pegasus’ nose. A globular star cluster, M 15, lies exactly halfway between Pegasus’ nose and Equuleus. This too is easily seen in binoculars.

This is Dudley Observatory’s Skywatch Line for Friday, July 3, through Sunday, July 5, written by Sam Salem.

On Friday, Sun rises at 5:22am and sets at 8:37pm; Moon sets at 3:48am and rises at 7:27pm.

The Moon will reach its full phase on Sunday, at 12:44 a.m. This full Moon will feature a shallow penumbral lunar eclipse. The entire eclipse will be visible from all of Central and South America, the southeastern half of North America, and western Africa. The latter stages of the eclipse will be visible in the rest of the USA, except Alaska. For us in the Americas, the Moon will turn precisely full during the nighttime hours on Saturday-Sunday, to present a partial Penumbral eclipse of the Moon. It’ll be such a faint eclipse that some will not notice it even while staring straight at it.

On Saturday, at 7:34 a.m. Earth will reach aphelion, its maximum distance from the Sun for this year. The aphelion distance of 94,511,180 miles is 1.67 per cent farther from the Sun, than the mean Earth-Sun separation of 92,955,807.3 miles, which is also defined to be 1 Astronomical Unit (1 AU). Earth’s perihelion, or minimum distance from the Sun, will occur on January 4.

When the full Moon rises over the southeastern horizon at dusk on Sunday, it will form a triangle below Jupiter and dimmer, yellow-tinted Saturn. The Moon and planets will fit within the field of view of binoculars. Over the course of the night, the diurnal rotation of the sky will shift the Moon to the planets’ left, and the Moon’s orbital motion will carry it closer to Saturn than Jupiter. Jupiter and Saturn are now at their best. Later this month, Earth will pass between each of these planets and the Sun, so that both Jupiter and Saturn reach their oppositions. Jupiter reaches opposition on July 13-14 and Saturn on July 20.

In the eastern pre-dawn sky between July 3 and 12, Venus’ orbital motion will carry it directly through the Hyades star cluster, the large, triangular grouping of stars that forms the face of Taurus, the bull. Its traverse offers an opportunity to easily see the daily motion of a planet. Look with unaided eyes while the sky is still somewhat dark, around 4:30 a.m. Use binoculars to nicely frame the planet and the cluster’s stars surrounding it.

From time to time, the small, round, black shadows cast by Jupiter’s four Galilean moons and the Great Red Spot can be seen in amateur telescopes as they cross, or transit, the planet’s disk for a few hours. Starting in late evening on Thursday, and continuing into Friday, see Ganymede’s relatively large shadow traverse the planet, accompanied by the Great Red Spot. Ganymede’s shadow will cross Jupiter’s northern hemisphere between 10:30pm and 1:50am. The spot will complete its passage by 1:30am. With a large telescope look for Ganymede’s pale disk following behind its shadow.

This is the Dudley Observatory Skywatch Line for Wednesday, July 1st, and Thursday, July 2nd, written by Louis Suarato.

The 86% illuminated, waxing gibbous Moon rises at 5:11 p.m. Wednesday, in the constellation Libra. By astronomical twilight, the Moon will be high over the southern horizon. Jupiter rises in Sagittarius at 9:18 p.m., followed by Saturn 20 minutes later. The two gas giants will be separated by about 6.5 degrees. Thursday night, beginning at 11:38 p.m., Jupiter’s largest moon, Ganymede, will transit the planet. At 1:51 a.m., Friday, Ganymede’s shadow transit will end. At 2:59 a.m., Ganymede’s transit will end. Saturn’s rings are inclined 22 degrees from edge on, providing a good view of the gap between the innermost ring, and the planet. Mars rises at 30 minutes past midnight in the constellation Pisces. Venus rises at 3:22 a.m. Thursday. Friday morning, Venus will be about 3 degrees above Taurus’ brightest star, Aldebaran.

The constellation Sagittarius rises above the southern horizon after midnight. Sagittarius is the fourteenth largest constellation. The majority of stars in this constellation form an asterism known as the Teapot. The “steam” emanating from the Teapot’s spout is the Milky Way. Within the steam, you’ll find, from lowest to highest, M8, the Lagoon Nebula, M20, the Trifid Nebula, open star cluster M23, M24, the Small Sagittarius Star Cloud, and open star cluster M25. Look between Jupiter and the Moon for these deep sky objects.

July 1st is the birth date of astronomer Maria Mitchell. Born in 1818 in Nantucket, Massachusetts, Mitchell was also a librarian, naturalist, and educator. Mitchell may be best known for the discovery of a comet in 1847 that was later to be known as “Miss Mitchell’s Comet”.

There will be an extremely bright -3.8 magnitude International Space Station pass over our region Thursday. The ISS will appear 30 degrees above the west-southwest horizon at 3:34 a.m. Thursday, to the right of the constellation Aquila, and its brightest star Altair. Follow the ISS as it rides along the spine of Cygnus the Swan, sailing past the stars Albireo and Deneb, the head and tail of the swan. Continue to follow the ISS as it passes through Cassiopeia, before heading toward the Double Cluster. The ISS will cross Perseus before disappearing into the northeastern horizon.

This is the Skywatch Line for Monday and Tuesday, June 29th and 30th, written by Joe Slomka.

The Sun sets at 8:37 PM; night falls at 10:53. Dawn begins at 3:05 AM and ends with the Sun rising at 5:21.

The Moon, past First Quarter in Virgo, rises Monday afternoon and sets at 2 AM, Tuesday. Tuesday finds he Moon, in Libra, also rising in the afternoon and at setting at 2:31 AM, Wednesday. Tuesday night finds the Moon about 2° from the star Alpha Librae (also known as Zubenelgenubi).

Jupiter is the first planet to rise, in Sagittarius, at 9:30 PM; it shines with brilliant 2nd magnitude and appears about 47 arc-seconds in size. Observers with binoculars or telescopes can witness the moon Europa begin to cross Jupiter’s face at 11:42 PM on Tuesday. Those with large telescopes and dark skies can see Pluto less than a degree from Jupiter, which sets after sunrise.

Saturn, in Capricornus, rises shortly after Jupiter, shining with zero magnitude and 18 arc-seconds. One hour before sunrise on Tuesday, Saturn and Jupiter lie about 6° from each other.

Neptune, in Aquarius, rises about Midnight, glowing with 8th magnitude and appearing a tiny 2 arc-seconds. Mars follows about a half-hour later, shining with minus zero magnitude and now 11 arc-seconds in size. Mars now appears about 84% lit and 33° high in the pre-sunrise sky. Mars and Neptune are about 10° apart.

Uranus rises next at 2 AM in Aries. The blue-green planet is about 6th magnitude and 3 arc-seconds. Venus, in nearby Taurus, rises last at 3:34 AM, blazing with minus 4th magnitude, 43 arc-seconds, 18% illuminated, but only 4° high.

About 7:15 AM, on June 30, 1908, a bright object roared out of the sky and exploded over a Siberian forest. The resulting blast knocked people off their feet 70 kilometers away. Night skies were so bright the one could read a newspaper at midnight. Barometers around the world monitored the blast wave. Tuesday is the 112th anniversary of the Tunguska Event.

The region, near the Tunguska River, was so remote that it took years for word to arrive at Moscow. Twenty years later, scientist Leonid Kulik led an expedition. He found the forest devastated for miles, with trees felled in a radial pattern from a central area. Suspecting a meteor, the expedition dredged the swamp to no avail.

Thanks to microscopic traces, we now know that the object was an asteroid that entered the Earth’s atmosphere. It exploded several miles above the surface with a force between three and five times the Hiroshima Atomic Bomb. Recent research also revealed that the object was smaller than first thought. In 1947, a large asteroid broke apart and impacted the Kamchatka Peninsula, also in Russia. Pictures exist showing Soviet trucks pulling thousand kilo meteorites from the ground. Today, meteor collectors buy pieces of the Sikote-Alin meteorite, as it is now called. A third similar event happened on February 13th 2016. A similar bright object dazzled citizens of the Russian city of Chelyabinsk and exploded, damaging property and injuring many people.

This is Dudley Observatory’s Skywatch Line for Friday, June 26, through Sunday, June 28, written by Sam Salem.

On Friday, Sun rises at 5:19am and sets at 8:38pm; Moon sets at 12:08am and rises at 10:56am.

On Saturday evening, the Moon shines about 8 degrees under Leo’s 2nd-magnitude tail-tip star, Denebola. Denebola forms an almost perfectly equilateral triangle with brighter Spica off to its left and Arcturus above them. All three sides of the triangle are close to 35 degrees long. This has been called the Spring Triangle. The Moon reaches its first quarter phase on Sunday, at 4:16 a.m. At that time, the relative positions of the Earth, Sun, and Moon will cause us to see the Moon half-illuminated on its right-hand side. Sunlight striking the Moon at a shallow angle produces spectacularly illuminated landscapes along the pole-to-pole terminator line that separates the lit and dark hemispheres. First quarter moons always rise around noon and set at midnight, so they are visible starting in the afternoon hours.

Several times a year, for a few hours near its first quarter phase, a feature on the Moon called the Lunar X becomes visible in strong binoculars and backyard telescopes. If skies are clear, point your lenses to the Moon this Saturday around 8pm. The Lunar X is predicted to peak in intensity at 8pm, but the phenomenon will be visible for approximately two hours on either side of that time. When the rims of the craters Parbach, la Caille, and Blanchinus are illuminated from a particular angle of sunlight, they form a small, but very obvious X-shape. The Lunar X is located near the terminator, about one third of the way up from the southern pole of the Moon. The prominent round crater Werner sits to its lower right.

Venus is getting a little higher and easier to spot every morning in the east-northeast as dawn brightens. Venus is low in the dawn, look for it just above the east-northeast horizon. If you look early enough before dawn grows bright you may be able to catch the Pleiades 9 degrees above it. Venus is on its way up to a fine showing as the bright Morning Star through summer and fall. Mars, at magnitude –0.4, rises in the east around 1am shining bright orange at the Aquarius-Pisces border. Watch for it to clear the horizon lower right of the Great Square of Pegasus. By the first light of dawn, Mars shines high and prominent in the southeast. In a telescope Mars has grown to 11 arc-seconds in apparent diameter. Mars is as gibbous as it gets, 84% sunlit. Mars will appear fully twice this diameter when it passes closest by Earth around opposition in the first half of October. Neptune, at magnitude 7.9 in constellation Aquarius, is well up in the southeast before dawn begins, in the vicinity of Mars.

Jupiter and Saturn now rise around the end of twilight. Jupiter rises first, then dimmer Saturn follows, about 20 minutes behind, lower left of Jupiter. The planets are about 5½ degrees apart. Look farther to Jupiter’s right to see the Sagittarius Teapot resting upright. The two giant planets shine at their highest and telescopic best around 3 a.m. Jupiter and Saturn straddle the border of constellations Sagittarius and Capricornus. Jupiter will reach opposition on the night of July 13th, Saturn on July 20th.

This is the Dudley Observatory Skywatch Line for Wednesday, June 24th, and Thursday, June 25th, written by Louis Suarato.

The 17% illuminated, waxing crescent Moon sets at 11:34 p.m., Wednesday. Look for M44, the Beehive Cluster, to the Moon’s lower left. Thursday, the Moon moves into the constellation Leo, and will be about 6 degrees above its brightest star, Regulus. Over the eastern horizon, the asterism known as the Summer Triangle can be seen. The lowest star is Altair in Aquilla, to its upper left is Deneb in Cygnus, and completing the triangle is Vega in Lyra. Jupiter rises in the southeast, in the constellation Sagittarius, at 9:48 p.m., followed by Saturn 19 minutes later. Mars rises in Pisces 48 minutes after midnight. Venus is back in the pre-dawn sky. Look for Venus as it rises at 3:44 a.m. in Taurus.

To the upper left of the Moon, between Bootes’ brightest star, Arcturus, and Leo’s brightest star, Regulus, is a star cluster known as Melotte 111, in the constellation Coma Berenices. The 40 brightest stars within this cluster form a distinctive “V” shape. The Coma Star Cluster, as it is also known, covers 7.5 degrees, an area about twice the size of the Hyades Star Cluster. The stars within Melotte111 are approximately 350 million years old, and about 280 light-years away, making it the second nearest star cluster, after the Hyades. Coma Berenices was originally the tail of Leo before it became one of the 88 modern constellations. It was named for Ptolemy’s wife. Coma Berenices is not large, but it contains one galactic supercluster, two galactic clusters, one star cluster, and eight Messier objects, including several globular clusters. The Coma Cluster (Abel 1656) is one of the largest galaxy clusters, containing approximately 10,000 galaxies, mostly elliptical. Due to their distance. 230 to 300 million light-years away, most are only visible through large telescopes.

This is Dudley Observatory’s Skywatch Line for Friday, June 19, through Sunday, June 21, written by Sam Salem.

On Friday, Sun rises at 5:17am and sets at 8:37pm; Moon rises at 4:06am and sets at 7:13pm. At its new phase on Sunday, at 2:41 a.m., the Moon will be travelling between the Earth and the Sun, for an annular solar eclipse. The partial eclipse will not be visible from the US, but can be seen throughout eastern Africa, southern Europe and the Middle East, most of Asia and Southeast Asia. This new Moon will occur 6.2 days past apogee, resulting in a thin-ringed annular solar eclipse visible across central Africa and southern Asia.

For about an hour before sunrise on Friday, the very slim crescent of the old Moon will sit very close to the bright planet Venus. Look for the pair just above the east-northeastern horizon. The Moon and Venus will fit together in the field of view of binoculars and backyard telescopes.

On Saturday, the June solstice arrives at 5:44 p.m. This is when the Sun reaches its northernmost declination in Earth’s sky and begins its six-month return southward. Summer begins in the Northern Hemisphere, winter in the Southern Hemisphere. For us northerners, this is the longest day and shortest night of the year. On Saturday, the day is 15 hours, 20 minutes, and 20 seconds long (Schenectady latitude). In terms of daylight, this day is 6 hours, 19 minutes longer than on December Solstice. It’s also the day when the midday Sun passes the closest it ever can to being straight overhead, and thus when your shadow becomes the shortest it can ever be at your location.

Mercury is ending its apparition in evening twilight. The little planet is fading fast, while dropping out of view deep into bright twilight. Venus is very deep in the glow of sunrise. Venus is on its way up to becoming the bright Morning Star of summer and fall in a few days. Mars, at magnitude –0.2, rises in the east around 1 a.m., shining bright orange at the constellations Aquarius-Cetus border. By the first light of dawn Mars is fairly high in the southeast for telescopic viewing. This week Mars grows from 10 to 11 arc-seconds in apparent diameter. In a telescope Mars is as gibbous as it gets, 84% sunlit.

Jupiter and Saturn rise in late evening. Jupiter rises first, a few minutes after 10pm, then dimmer Saturn following about 20 minutes behind. They’re 5 degrees apart. Look for the Sagittarius Teapot resting upright farther to Jupiter’s right. The two giant planets shine at their highest and telescopic best in the hour or so before the beginning of dawn. They straddle the border of Sagittarius and Capricornus.

This is the Dudley Observatory Skywatch Line for Wednesday, June 17th, and Thursday, June 18th, written by Louis Suarato.

The 11% illuminated, waning crescent Moon sets at 5:04 p.m., Wednesday. It will rise as a trimmer 8% illuminated Moon at 3:02 Wednesday morning, approximately 11 degrees above Venus. Friday morning, the 1% illuminated Moon may occult 8% illuminated Venus, depending on your location. You will require a clear east-southeastern horizon to see the Moon and Venus paired up so closely. Begin to look at moonrise, which will occur around 6 minutes past 3 in the morning. Jupiter rises at 10:18 Wednesday night, followed by Saturn 8 minutes later. Mars rises at 1:05 a.m., Thursday. Mercury is stationary at 4 p.m. Wednesday, and begins its retrograde motion. The innermost planet will be 10 degrees above the horizon after sunset, and will be below the horizon in one hour.

June 17 is the birth date of astronomer William Parsons. Born in 1800. Parsons discovered and named the Crab Nebula. Parsons also built a 72 inch telescope named Leviathan in 1845, the largest in the world at the time. The Leviathan telescope was surpassed by the 100 inch Hooker telescope in 1917. The Crab Nebula, also known as M1, was discovered in 1840. This supernova remnant in the constellation Taurus dates back to records by Chinese astronomers of a supernova that occurred in 1054 AD. Is estimated to be 6,500 light-years away in the Perseus arm of the Milky Way. This supernova is expanding at 930 miles per second, or 0.5% the speed of light. At the center of the nebula is the Crab Pulsar. Discovered in the 1960’s by Franco Pacini, it emits pulsars once every 33 milliseconds. Look for the Crab Nebula in this summer’s pre-dawn sky to the lower left of Taurus’ brightest star, Aldebaran.

June 18 is the anniversary of another supernova. In 1918, Discovered by Zygmunt Laskowski, for months it was the brightest star in the sky, at magnitude -0.5, and the brightest nova in the era of the telescope. Nova Aquila was estimated to be about 784 to 839 light-years away. In its place, is now an 11th magnitude binary star system.