Category Archives: Skywatch Line

This is Dudley Observatory’s Skywatch Line for Friday, June 12, through Sunday, June 14, written by Sam Salem.

On Friday, Sun rises at 5:16am and sets at 8:34pm; Moon rises at 1:13am and sets at 12:05pm. Last quarter Moon occurs at 2:24am on Saturday. At last quarter, the Moon rises around midnight (standard time) and remains visible in the southern sky during morning daylight.

Earliest sunrise of the year happens these days. That’s despite of the fact that the summer solstice, and the year’s longest day, are still about a week away. The exact date of earliest sunrise, and latest sunset, varies with latitude. In our area, Sun rises at 5:16am since Thursday. This is the earliest sunrise time of the year. Sun will rise a minute later starting next Friday.

Look for the last quarter Moon passing Mars and Neptune this Weekend. In the southeastern pre-dawn sky, Mars will sit near, dim, and blue-tinted Neptune. At closest approach, Neptune will sit 1.5 degrees to the north of Mars, allowing both planets to appear together in the field of view of amateur telescopes. Magnitude -0.19 Mars will shine nearly 1700 times brighter than magnitude 7.9 Neptune.

The waning half-illuminated Moon will pass, four finger widths, to the lower left of Mars in the southeastern sky in the hours before dawn on Saturday. The duo will fit into the field of view of binoculars. Mars is brightening and enlarging. In a telescope it’s now 10 arc-seconds wide, a little gibbous disk 85% sunlit. Mars, in dim Aquarius, is 40° to 45° left of Saturn, as dawn begins. Saturn glows pale yellow, 5 degrees to Jupiter’s left.

Mercury remains under Pollux and Castor in evening twilight. It has now faded to magnitude 1.3. That’s less than half as bright as Procyon, mag 0.4. Mercury will appear even fainter considering the greater atmospheric extinction at its lower altitude and the brighter sky there too. Binoculars may help.

In the evening sky this weekend, the orbital motion of the main belt asteroid designated (2) Pallas will take it 1.5 finger widths to the upper left of the Coathangar Cluster in the constellation of Vulpecula. Also considered an asterism, the Coathangar is an easy target for binoculars, located midway between the bright stars Vega and Altair. The magnitude 8.94 asteroid and most of the cluster’s stars will appear together in the field of view of telescopes at low magnification.

The big Summer Triangle shines high in the east after dark. As dusk deepens into night, look eastward for this great star pattern, an asterism made of three bright stars in three different constellations. Look for the brightest star in eastern sky, Vega, the brightest star in the constellation Lyra the Harp. Look to the lower left of Vega for another bright star Deneb, the brightest in the constellation Cygnus the Swan and the third brightest in the Summer Triangle. An outstretched hand at arm’s length approximates the distance from Vega to Deneb. Look to the lower right of Vega to locate the Summer Triangle’s second brightest star, Altair, the brightest star in the constellation Aquila the Eagle. A ruler held at arm’s length fills the gap between these two stars. Under dark, moonless, sky, the Milky Way runs through the Triangle’s lower part from side to side.

This is the Dudley Observatory Skywatch Line for Wednesday, June 10th, and Thursday, June 11th, written by Louis Suarato.

Wednesday, the 77% illuminated, waning gibbous Moon sets at 10:02 a.m., before rising again at 44 minutes past midnight on Thursday. Mercury remains in the sky until 10:08 p.m., between the Gemini twins. Look for Mercury low over the west-northwestern horizon after sunset. Jupiter rises at 10:48 p.m., followed by Saturn 16 minutes later. The gas giants will be between the constellations Capricornus and Sagittarius. Mars joins Jupiter and Saturn at 1:24 a.m., 40 minutes past moonrise. Friday, the Moon and Mars will rise side by side, separated by 10 degrees. The pre-dawn sky demonstrates how the plane of the ecliptic, the planets path around the Sun, flattens around the time of the solstice. Mars, Saturn and Jupiter span 61 degrees, but their difference in altitude is only 3 degrees.

Astronomical Twilight, when the Sun is between 12 and 18 degrees below the horizon, and most stars can be seen, occurs at 10:48 p.m., Wednesday. If you look up at the sky at that time, you can see Cygnus, the Swan, taking off from the northeastern horizon. Cygnus’ brightest star is Deneb, or Alpha Cygni, a first magnitude white supergiant star, at the tail of the Swan. Deneb is one of the largest, and most luminous A-Class stars. Deneb is also a component of the asterisms known as the Summer Triangle, and the head of the Northern Cross. To the east of Deneb, at the center of the Cross, and between the Swan’s wings are four open star clusters. M29, or NGC 7092, contains about 30 stars, the brightest of which are 7th magnitude. NGC 6910, The Rocking Horse Cluster, has 16 stars, the brightest being 2 gold stars. Farther east is a younger open star cluster, IC 4996. The stars in this cluster have been estimated to be between 8 and 10 million years. The fourth cluster is NGC 6871. This small cluster contains about 50 stars, mostly blue and white, estimated to be about 9 million years, and 5,135 light-years away. At the very tip of the Swan is the star Albireo. Albireo is a gem of a double star comprised of gold and blue stars. Use a low power telescope to split and resolve these stars.

This is Dudley Observatory’s Skywatch Line for Friday, June 5, through Sunday, June 7, written by Sam Salem.

On Friday, Sun rises at 5:18am and sets at 8:30pm; full Moon occurs at 3:12pm, Moon sets at 5:11am and rises at 8:36pm. A penumbral lunar eclipse will also occur on Friday. The eastern portion of South America, as well as Africa, Australia, Europe, and much of Russia, will be able to view all or part of the event. No eclipse takes place in North America. All the action will be happening while the Moon is below our horizon. A penumbral eclipse occurs when the Moon passes through the lighter portion of Earth’s shadow, called the penumbra, causing a shading effect, although none of the Moon will go completely dark.

As the stars come out on Friday, look to the right of the full Moon, by roughly a fist at arm’s length, for orange Antares, the red supergiant star, brightest star in the constellation Scorpius the Scorpion.

Mercury is having a nice apparition in evening twilight. Look for it in the west-northwest as twilight deepens. Mercury is fading from magnitude 0.0 last Sunday to +0.7 on Saturday, a loss of half its light. On Friday, try to catch Mercury in twilight, under Pollux and Castor, the two brightest stars in constellation Gemini, the twins.

Venus is lost in the Sun’s glare for the first week or two in June. Venus swung in front of the Sun, at inferior conjunction, on Wednesday, to transition out of the evening sky and into the morning sky. Look for Venus to reappear in the eastern dawn by around mid-June.

If you stay up very late on Sunday night, you can glimpse the Moon with the bright planets Jupiter and Saturn, ascending in the east. You can also see them before daybreak, in your southern sky. Jupiter and Saturn are near one another on the sky’s dome, with Saturn following Jupiter westward across the sky from mid-to-late evening till dawn. Look first for brilliant Jupiter and you’ll find Saturn a short hop to the east of it. Saturn pales next to Jupiter, which outshines Saturn by some 15 times. Even though Moon will be bright, use a telescope to watch Jupiter with only 1 satellite visible at 2:17am on Saturday.

Mars, in dim constellation Aquarius, is far to the left of Saturn as dawn begins. It has been slowly brightening and enlarging. Mars, which is a bit brighter than Saturn, more or less aligns with Jupiter and Saturn in the predawn/dawn sky. However, Mars is a long jump to the east of Jupiter and Saturn. Saturn shines between Jupiter and Mars, much closer to Jupiter. Mars is the last of the three bright morning planets to rise in June. Jupiter rises first, closely followed by Saturn, and then a few to several hours later by Mars.

This is the Dudley Observatory Skywatch Line for Wednesday, June 3rd, and Thursday, June 4th, written by Louis Suarato.

The 95% illuminated, waxing gibbous Moon rises at 6:15 p.m. Wednesday. The star below the Moon Thursday night is the constellation Scorpius’ brightest, Antares. Antares, meaning “rival of Mars” because of its reddish color, is a variable star with its brightness ranging from magnitude +0.6 to +1.6, making it the 15th brightest star in our sky. Look for Mercury low over the west-northwestern horizon after dusk. As the sky darkens, you’ll be able to see the Gemini twins, Castor and Pollux, above Mercury. Mercury reaches its greatest eastern elongation at 24 degrees beyond the Sun at 9 a.m., Thursday. Venus is in inferior conjunction at 2 p.m., Wednesday, when the planet is between Earth and the Sun. Jupiter rises at 11:17p.m., followed by Saturn 16 minutes later and 4 degrees away from Jupiter. Both gas giants occupy Sagittarius. Look for the Great Red Spot to begin its transit of Jupiter beginning 14 minutes past midnight Thursday. Mars rises at 1:40 Thursday morning in Aquarius.

On June 3, 1769. James Cook, aboard the ship, The Endeavour, sailed to Tahiti to witness the Transit of Venus across the face of the Sun. Cook, and his team of naturalists, and scientists, along with others around the globe, would use a process known as parallax, to determine the size of Venus, and by comparison, other planets. Transits of Venus occur in pairs, eight years apart, and separated by 120 years. This would be the last opportunity for these scientists to view the Transit. That transit of Venus was followed five hours later by a total eclipse of the Sun. It was the shortest interval between a Transit of Venus and Total Eclipse of the Sun in history. Our last Transit of Venus took place in 2012. The next one will occur on December 10th and 11th, 2117.

This is Dudley Observatory’s Skywatch Line for Friday, May 29, through Sunday, May 31, written by Sam Salem.

On Friday, Sun rises at 5:21am and sets at 8:25pm, the first quarter Moon sets at 1:32am and rises at 11:53am. Moon reaches its first quarter phase on Friday at 11:30pm. As darkness falls on Friday and Saturday, watch the Moon as it travels in front of the constellation Leo the Lion. As stars come out, the Moon is high in the southwest below the belly of Leo’s stick-figure lion pattern. The Moon forms a nearly equilateral triangle with Leo’s Regulus to its lower right and Gamma Leonis, or Algieba, slightly fainter, more directly to the Moon’s right.

Look for Mercury in evening twilight, in the west-northwest. By this weekend, Venus has dropped out of sight. Mercury fades from magnitude –0.6 to 0.0. In a telescope it is a tiny “half-moon” shape, 7 arc-seconds in diameter.

Mars, Jupiter, and Saturn shine in the southeast to south before and during early dawn. Jupiter, the brightest, is on the right. Saturn glows pale yellow 4 degrees to Jupiter’s left. They both rise now around midnight. They straddle the border of Sagittarius and Capricornus. Mars, in dim constellation Aquarius, is 35 degrees to 40 degrees to the left of Saturn as dawn begins. It has been slowly brightening and enlarging. In a telescope, Mars is now 9 arc-seconds wide, a little gibbous disk. Neptune, at magnitude 7.9, in Aquarius, is fairly low in the east-southeast before dawn begins.

Capella is still up in the northwest in twilight, but it sets in the northwest fairly soon after dark. That leaves Vega and Arcturus as the brightest two stars in the evening sky. Both are magnitude 0. Vega shines in the east-northeast. Arcturus is very high toward the south. A third of the way from Arcturus to Vega, look for semi-circular Corona Borealis, the Northern Crown, with 2nd-magnitude star Alphecca, or Gemma, the jewel of the crown. Two thirds of the way from Arcturus to Vega is the dim Keystone of Hercules. Use binoculars or a telescope to examine the Keystone’s top edge. A third of the way from the edge’s left end to the right is 6th-magnitude M13, one of Hercules’s two great globular star clusters. In binoculars it’s a tiny glowing cotton ball. A scope resolves some of its details. M13 consists of several hundred thousand stars in a swarm about 140 light-years wide.

Friday marks the 101st anniversary of the solar eclipse permitted observation of the bending of starlight passing through the Sun’s gravitational field as predicted by Albert Einstein’s theory of relativity. Separate expeditions of the Royal Astronomical Society travelled to Brazil and off the west coast of Africa. Both made measurements of the position of stars visible close to the Sun during a solar eclipse. These observations showed that, indeed, the light of stars was bent as it passed through the gravitational field of the Sun.

This is the Dudley Observatory Skywatch Line for Wednesday, May 27th, and Thursday, May 28th, written by Louis Suarato.

The 30% illuminated, waxing gibbous Moon sets 58 minutes after midnight Thursday. Mercury and Venus continue to go their separate ways as Venus sets at 9:18 p.m., and Mercury sets about an hour later. The Moon will be to their upper left, beyond the Gemini twins Castor and Pollux, in the constellation Cancer, and close to M44, the Beehive Cluster. Thursday night, the bright star to the left of Jupiter is Regulus, Leo’s brightest. The First Quarter Moon occurs at 11:30 Thursday night. Jupiter rises at 11:45 p.m., followed by Saturn at 4 minutes past midnight, The shadow of Jupiter’s largest moon, Ganymede, begins to cross the planet at 2:35 a.m., Thursday. Europa’s shadow joins Ganymede’s at 4:46 a.m. Mars rises at 1:54 a.m. in Aquarius.

It’s been about a decade since a manned space flight launched from the United States. Ever since the termination of the Space Shuttle missions, NASA has been utilizing the services of Russia to transport their astronauts to the International Space Station. That may change this week when NASA teams up with Elon Musk’s SpaceX to launch to next crew to the space station. At the time of this writing, the launch is scheduled for Wednesday, May 27 at 4:43 p.m. EDT.

The International Space Station will be making a bright pass over our region beginning at 10:36 p.m. Wednesday. This -3.0 magnitude pass will begin from the northwestern horizon and sail over Auriga’s brightest star, Capella, before heading toward the Little Dipper. After passing close to Polaris, the North Star, the ISS will continue on through Draco, and Lyra, passing its brightest star, Vega, where it will disappear in Earth’s shadow.

This is the Skywatch Line for Monday and Tuesday, 25th and 26th, written by Joe Slomka.

The Sun sets at 8:21 PM; night falls at 10:28. Dawn begins at 3:16 AM and ends with the Sun rising at 5:23.

The Moon occupies Gemini on both nights. Monday’s 3-day-old Moon is moderately low in the western sky, shines with minus 9th magnitude, 11 percent illuminated and sets at 11:22 PM. Tuesday’s Moon is a bit higher, larger, 18% lit and sets at 12:12 AM on Wednesday. Note that on Monday, the Moon rested between Gemini’s legs and on Tuesday will be 6° left of the bright star Pollux.

Venus and Mercury are bright evening planets, sharing Taurus. Venus rose first, and by Civil Twilight, is a very thin crescent, 4° high, minus 4th magnitude and sets at 9:31 PM. Mercury, is dimmer with minus 0 magnitude, much smaller, but 7° higher than Venus. Observers will see that Venus becomes progressively lower, in preparation for next week’s inferior conjunction with the Sun, while Mercury is higher.

The pre-sunrise south-eastern sky is full of interesting objects. Dwarf Planet Pluto rises first in Sagittarius at 11:53 PM, Monday; it glows with 14th magnitude and appears a fraction of an arc-second. It is situated only 2° from giant Jupiter, which rises 4 minutes later, is much brighter with minus 2nd magnitude and a huge 44 arc-seconds in size. Saturn, in Capricornus, rises Tuesday at 12:16 AM, shining with zero magnitude and 17 arc-seconds. Pluto, Jupiter and Saturn are all about 23° in altitude. Mars, in Aquarius, continues its eastward plunge, rising at 2:04 AM, also shining at 0 magnitude, 9 arc-seconds in size, 85% lit, and 13° high. Neptune, also in Aquarius, is only 12° east of Mars; it rises at 2:26 AM, shines with 8th magnitude and is a moderate 2 arc-seconds in size. Finally, Dwarf Planet Ceres, also in Aquarius, lies 7° east of Mars, shines with 9th magnitude and is 13° high by Dawn. Uranus rises in Aries at 4:13 AM, shines with 6th magnitude, and 3 arc-seconds in diameter. Pluto, Ceres, Uranus and Neptune may require sky charts to locate them, available from various astronomical media.

Comet Swan (C/2020 F8) has the unusual distinction of appearing very low in both the Twilight and Dawn skies in the constellation Perseus. On Monday’s Civil Twilight, at about 9 PM, it is found west of the star 53 Per and about 23° east of Venus. A slightly better view is available on Tuesday Civil Dawn, when it lies about 7° high in the north-eastern sky in almost the same position in Perseus and not far from Auriga’s bright star Capella.

If you follow the “arc” of the Big Dipper’s handle, you come to the bright star Arcturus. Arcturus is the sixth brightest star and one of the nearest, only 37 light-years away. Arcturus is a giant, about 25 times larger than our Sun. Astronomers have known, for some time, that Arcturus is rapidly approaching our solar system. Several thousand years from now, Arcturus will brighten, loom larger, speed past us and then disappear into space. A new theory thinks that Arcturus, and other stars, are actually part of a small galaxy that our own Milky Way gobbled up in the recent past.

This is Dudley Observatory’s Skywatch Line for Friday, May 22, through Sunday, May 24, written by Sam Salem.

On Friday, Sun rises at 5:26am and sets at 8:19pm, the waxing crescent Moon rises at 5:33am and sets at 8:21pm. New Moon occurs on Friday at 1:39pm.
On Saturday, catch the super-thin crescent Moon, hardly more than a day old very low below Venus and Mercury while twilight is still bright. The waxing crescent Moon will join Mercury and Venus in the west-northwestern sky after sunset on Sunday. Look for the Moon’s slim crescent sitting a fist’s width to the upper left of very bright Venus, with much dimmer Mercury between them.

On Friday, Mercury and Venus are still close together, 1.7 degrees apart. Thereafter they separate again, with Mercury now on top. Mercury fades from magnitude –1.1 to –0.6. Venus, in northern constellation Taurus, is dropping fast now. It shines brightly in the west-northwest in twilight, as it heads down toward its June 3rd conjunction with the Sun. Venus fades from magnitude –4.6 to –4.3 but remains a dazzler. Mercury sets around 10PM and Venus sets a couple of minutes earlier. A little farther above Venus each evening is Beta Tauri, magnitude 1.6. Mercury climbs rapidly up from the horizon day by day to meet it.

Mars, Jupiter, and Saturn shine in the southeast to south before and during early dawn. Jupiter, the brightest, is on the right. Before dawn begins, spot the Sagittarius Teapot off to the lower right of it. Saturn glows pale yellow 4 degrees to Jupiter’s left. Mars, in constellation Aquarius, is much farther, 30 degrees to 35 degrees, to Saturn’s left as dawn begins. It has been slowly brightening and enlarging. In a telescope Mars is now about 8.5 arc-seconds wide, a tiny gibbous disk.

In the southeastern pre-dawn sky on the mornings surrounding Sunday, the west to east orbital motion of the dwarf planet Ceres will carry it a generous palm’s width below, or 7 degrees, to the celestial south of Mars. The asteroid will shine at magnitude 8, much dimmer than Mars’ magnitude 0.1. However, Ceres should be readily visible in binoculars if you use the stars Skat and Tau Aquarii to help you locate it. Skat or Delta Aquarii appears modestly bright in a dark country sky. It’s near on the sky’s dome to a very bright star, Fomalhaut in the constellation Piscis Austrinus, the Southern Fish. If you can see the Great Square of Pegasus and Fomalhaut, they can help you find Skat. Find Skat by first finding the Great Square of Pegasus. Skat is found roughly on a line drawn southward through stars on Square’s west side. It’s between the Great Square and the bright star Fomalhaut.

Less than two binoculars fields to the left of Mars, distant Neptune will be shining with the same intensity as Ceres. Look for that blue planet sitting just a few degrees to the lower left of the star Phi Aquarii.

This is the Dudley Observatory Skywatch Line for Wednesday, May 20th, and Thursday, May 21st, written by Louis Suarato.

The 3% illuminated, waning crescent Moon sets at 6:12 p.m. Wednesday. The Moon rises as a thinner crescent at 5:03 Thursday morning. Mercury and Venus shine 2 degrees apart over the west-northwestern horizon after sunset. Mercury is on the far side of the Sun, while Venus is on the side closer to Earth, making Mercury 3.5 times more distant. Venus is the much brighter of the two innermost planets, shining at -4.7 magnitude, and 6.4% illuminated. Jupiter rises at 11 minutes past midnight, followed by Saturn 15 minutes later. The two gas giants will be 4.5 degrees apart. Mars rises at 2:13 a.m. in the constellation Aquarius.

Get up and out an hour before sunrise to look for Comet C/2020 F8 (SWAN). Use binoculars to scan low over the northeastern horizon for this 4th magnitude comet. The comet will be about 15 degrees below the Double Cluster. The Double Cluster can be found below Cassiopeia. This week may be the best week to view the comet before it is lost in the Sun’s glare. Comet SWAN reaches perihelion, its closest distance to the Sun, on Tuesday, May 26th.

On May 20, 1990, the Hubble Space Telescope sent its first photograph from space. The photo was of a double star, 1,260 light-years away. Also on May 20, in 1825, George P. Bond was the first to photograph a star (Vega), and a double star (Mizar).

The Albany Area Amateur Astronomers invite you to join them for their monthly meeting, which will again be held online. The speaker this month will be Dr. Valerie Rapson, Director of the Dudley Observatory. Dr, Rapson’s presentation will be “Curiosity, Insight, Perseverance, and Ingenuity” about Mars exploration. To supplement the current activities being conducted by the Mars rover, Curiosity, and Insight lander, this July, NASA will launch the Mars 2020 rover, Perseverance. The instrumentation will include a new drone device called Ingenuity. The meeting will be held Thursday, May 21 beginning at 7:30 pm via Zoom.

This is the Skywatch Line for Monday and Tuesday, May 18th and 19th, written by Joe Slomka.

The Sun sets at 8:15 PM; night falls at 10:17. Dawn begins at 3:25 AM and ends with the Sun rising at 5:29.

The Moon is not seen on both nights. Tuesday’s 26-day-old Moon rises at 4:17 AM, is 10% illuminated, 6° high and sets at 5:15 PM. Wednesday’ Moon rises at 4:40 AM, is 6% lit and sets at 6:16 PM.

Two evening planets share Taurus. Venus is the brightest planet in the sky. It blazes with minus 4th magnitude, appears as a thin crescent, 8% lit and 14° high and sets at 10:17 PM. Mercury now appears 7° below Venus, appearing 77% lit, 7° altitude, glaring with minus zero magnitude and setting at 9:36 PM.

The pre-dawn sky is where the action is. Sagittarius houses Jupiter and Pluto. Dwarf planet Pluto actually rises first at 12:25 AM, shining with 14th magnitude, appearing less the one-arc second diameter and 22° high. Jupiter rises 4 minutes later, glowing with minus 2nd magnitude and 43 arc-seconds wide.

Saturn is the second major planet to rise, in Capricornus, at 12:44 AM, shining with zero magnitude and 17 arc-seconds breadth. Mars is socially distancing itself from the rest. It rises, in Aquarius, at 2:20 AM, appears a bit smaller than Saturn but almost 9 arc-seconds and 24° high. The Red Planet shares Aquarius with Neptune, which rises at 2:54 AM, 8th magnitude bright, 21° high and a small 2 arc-seconds. Another Dwarf planet, Ceres, also in Aquarius, rises at 2:56 AM below Mars is 97% lit, 17° high and shines with 8th magnitude, making it visible in 6-inch telescopes.

If that wasn’t enough, we have an interloper in our pre-sunrise sky. Comet Swan (C/2020 F8) is making a low appearance in the north-east sky. The comet was discovered by Australian amateur astronomer Michael Matiazzo on March 25th through the SWAN telescope. The comet is very bright and obvious in the southern hemisphere sky, but now it rises at 2:43 AM in the constellation Triangulum on Tuesday morning, and Perseus on Wednesday. It shines with 5th magnitude and is 8° high at 4 AM and 12° at 4:30. Wednesday finds it one-half degree away from the variable star Algol,

Putting it within the same finder scope field. Comet Swan also has an evening apparition from about May 23rd to June 10th for mid-northern observers.

Saturn is the showpiece of any star party. But, Saturn is not the only planet that has rings. Jupiter, Uranus and Neptune were discovered to display rings by space-borne probes. A new member joins the club. In 2014, the European Space Organization (ESO) announced that Chariklo, an asteroid, possesses rings. This was an accidental finding. The ESO had several observatories study Chariklo as it occulted, or eclipsed, a star – to determine its size and shape. When they studied the results, the star was occulted three times. First it flickered; secondly the asteroid blacked it out; thirdly, it flickered again. Astronomers deduced that rings surrounding Chariklo caused the flickering. Chariklo is a Centaur asteroid: it is rock, enclosed by a fuzzy comet-like halo of gas. The occultation revealed that it is the largest Centaur – 160 miles in diameter.