Skywatch Line for Monday and Tuesday, June 17th and 18th, 2019

This is the Skywatch Line for Monday and Tuesday, June 17th and 18th, written by Joe Slomka

The Sun sets at 8:36 PM; night falls at 10:53. Dawn begins at 2:59 AM and ends with the Sun rising at 5:16.

The sky, at Civil Dusk, hosts 3 bright planets. In the West, Mars and Mercury jointly inhabit Gemini. Mars appears 98% illuminated, 3 arc-seconds in size and shines with 1st magnitude. However, it is only 10º high. Mercury lies a half degree from Mars, is 50% lit, shines with zero magnitude and is twice Mars’ apparent size. This is Mercury’s closest approach to Mars, and a rare chance to see 2 planets in the same binocular view. Both set at 10:19 PM.

Eastern Jupiter rises in Ophiuchus at 7:48 PM. It sparkles with minus 2nd magnitude and is 46 arc-seconds in size. By Nightfall, it is 21º high and is best observed at 12:25 AM. Telescopic observers can see Jupiter’s Great Red Spot at 10:05 PM on Monday and at 3:52 AM on Wednesday, but both events happen when the planet is quite low. Beginning at 12:06 AM on Wednesday, they can see the moon Io and its shadow crossing across the giant planet’s face; Io’s trip ends at 2:30 AM.

Dwarf planet 1Ceres rises in Scorpius at 11:25 PM, shines with 7th magnitude and is 27º high. The tiny asteroid lies about 2º from the star Graffias and sets at 4:14 AM. Finder charts are available from various astronomy websites.

Monday’s Full “Trees Fully Leafed” Moon rises, in Sagittarius, at 9 PM, blazing with 12th magnitude and 14º high. It is best observed at 1:41 AM and sets at 6:21 AM. Tuesday sees a thinner and slightly dimmer Moon rising at 9:53 PM, being best observed at 2:33 AM and setting after Sunrise.

Saturn rises in Sagittarius at 9:55 PM, shines with zero magnitude and about 18 arc-seconds in size. It is best observed at 2:31 AM and also sets after Sunrise. Tuesday’s Moon parks itself only 1º from Saturn all night, ruining views of its rings.

Neptune, in Aquarius, rises at 12:48 AM, glows with 7th magnitude and is 22º high at Dawn. Uranus, in Aries, rises at 2:31 AM, glistens with 5th magnitude. Early bird observers should begin as soon as possible due to the brightening sky.

Several dim but lovely constellations are sandwiched between brighter Pegasus, Aquarius and Cygnus. One of these is Delphinus, the Dolphin. It looks like a diamond with a tail and replicates a dolphin leaping out of the water. It is found midway between Pegasus’ and Cygnus’ noses.

There are two Greek myths about Delphinus. One states that Arion, a rich poet, was threatened by covetous crewmen while he was traveling. When he was flung into the sea, he was rescued by a dolphin, which carried the poet to the Greek coast.

Most star names are derived from legends or description. Delphinus is an exception. Its two brightest stars, Alpha and Beta, were the subjects of a practical joke. An Italian astronomer, Niccolo Cacciatore, decided to give them proper names. In Latin, his name was “Nicolaus Venator”. He assigned the names “Sualocin” to Alpha, and “Rotanev” to Beta. These names are “Nicolaus Venator” spelled backwards. The practical joke stuck! Today, these are accepted official names for Alpha and Beta Delphini.

Star names are a combination of various languages: Greek, Latin, Arabic, and invented as the example just mentioned. The Albany Area Amateur astronomers have their monthly meeting at miSci at 7:30 PM, Thursday. Club member Sam Salem will talk about stars with Arabic names. All club events are free and the public is welcome.

Skywatch Line for Friday, June 14 through Sunday, June 16, 2019

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

On Friday, Sun rises at 5:17am and sets at 8:36pm; the waxing gibbous Moon rises at 5:51pm and sets at 3:38am. On Saturday night, the bright Moon forms a triangle with Jupiter, to its lower left, and Antares, to its lower right. On Sunday evening, the nearly full Moon and Jupiter rise together side-by-side in the southeast at sunset. The two objects will be a little more than four degrees apart, offering a fine naked-eye sight early in the evening. Full Moon occurs on Monday at 4:31am.

Three planets emerge as evening twilight begins to fade. Mercury, in constellation Gemini, lies low in the west-northwest and gradually approaching Mars. On Sunday evening, Mercury lies 1 degree lower right of Mars. Use binoculars to watch the gap between the two planets noticeably shrink from night to night. This week Mercury fades by almost half, from magnitude –0.6 to –0.1. However, Mercury is much brighter than magnitude 1.8 Mars. Don’t confuse Mercury with Procyon, some 25 degrees to its left, or Capella, about the same distance to its right. Jupiter, gleaming at magnitude –2.6, rises in the southeast a little before sunset and culminates roughly around 12:30am. Saturn, at magnitude 0.2, rises a little before 10:30pm. It reaches the meridian around 2:30am. Venus, at magnitude –3.8, is very slowly losing altitude as its current apparition winds down. Venus clears the east-northeast horizon less than one hour before sunrise.

Jupiter and Saturn’s moons are good telescopic targets this moonlit weekend. Jupiter is at its brightest and closest to the Earth for the year. Swing your telescope to the giant planet’s way. Though it rises around sunset, it still takes time to climb high enough for a good view. Come the end of the month, Jupiter stands 20 degrees high before twilight ends. Try to observe Jupiter every clear night, the better to catch nights of calm and steady seeing when the planet sits rock-steady and sharp. When the air calms and seeing conditions allow, you can make out the prominent North and South Equatorial Belts. Jupiter’s iconic Great Red Spot (GRS) has been shrinking over the past several decades and currently spans about 1.3 Earths. But it remains colorful and easy to see at 100 times magnification and higher in good seeing conditions.

The moons of Saturn are all fainter than Jupiter’s moons but some are within range of small to moderate-sized telescopes. Titan shines gamely at magnitude 8.4, and is usually the brightest point of light near Saturn. With an 8-inch scope, you might see as many as four additional satellites, including Rhea (magnitude 9.7), Tethys (10.3), Dione (10.4) and, under the right conditions, Enceladus (11.8). At last count, Saturn has 62 satellites ranging in size from 5,149, Titan, down to jagged moonlets smaller than Mount Everest.

Skywatch Line for Wednesday, June 12th, and Thursday, June 13th, 2019

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

The 77% illuminated, waxing gibbous Moon rises at 3:37 p.m. Wednesday. At 9:30 p.m., the Moon will be 40 degrees above the southern horizon, while Jupiter, just 2 days past opposition, will be 10 degrees above the southeastern horizon. Jupiter’s Galilean moon events include Io emerging from behind the planet at 9:44 p.m. Wednesday, and Europa passing behind Jupiter beginning at 3:12 a.m., Thursday. Also at 9:30 p.m., look for Mars and Mercury 8 degrees above the west-northwestern horizon separated by 3 degrees. You may require binoculars to see both planets.. Mercury will be brighter, and to the right of Mars. Saturn rises at 10:15 p.m. Wednesday in the constellation Sagittarius.

Twilight helps you determine the Moon is in Virgo. To the right of the Moon is Virgo’s brightest star, Spica. Virgo is the second largest constellation and is rich in galaxies, including those that are part of the Virgo Cluster, which consists of 1,200 to 2,000 galaxies, such as:; Messier 49 (elliptical), Messier 58 (spiral), Messier 59 (elliptical), Messier 60 (elliptical), Messier 61 (spiral), Messier 84 (lenticular), Messier 86 (lenticular), Messier 87 (elliptical and a famous radio source), Messier 89 (elliptical) and Messier 90 (spiral). A galaxy that is not part of the cluster is the Sombrero Galaxy (M104), an unusual spiral galaxy. It is located about 10° due west of Spica.

Spica is the fifteenth brightest star in the sky. One of the reasons is its close proximity to Earth. Spica is only 250 light-years away. Spica is a close binary system, whose members are too close to be split telescopically. The two stars orbit each other once every 4.01 days. Use Spica to locate the constellation Virgo by beginning at the Big Dipper and following the arc of its handle to Arcturus, then speeding down to Spica.

Skywatch Line for Monday and Tuesday, June 10th and 11th, 2019

This is the Skywatch Line for Monday and Tuesday, June 10th and 11th, written by Joe Slomka.

The Sun sets at 8:33 PM; night falls at 10:48. Dawn breaks at 3:01 AM and ends with the Sun rising at 5:16.

Mars and Mercury share Gemini. Mars remains at 1.8 magnitude all month. It appears about 4 arc-seconds in size and about 13º high. Mars sets at 10:30 PM. Mercury is brighter, at magnitude minus 0.3, 64% illuminated but 9º high. Mercury sets at 10:12 PM. Note that Mars appears lower daily, while Mercury rises higher daily.

The Moon is at First Quarter on Monday night. In Virgo, the 8-day-old Moon appears about 59% lit and 32 arc-minutes in size, blazes with minus 10th magnitude, and is 47º high at Civil Dusk. Tuesday finds the Moon a bit fatter, brighter, but about the same size and 45º high. The Moon sets at 2:10 AM on Tuesday and at 2:38 AM, Wednesday.

Jupiter rises in the East, in Ophiuchus, at 8:19 PM. Monday, it reaches Opposition, which means it is up all night, at its brightest and at its closest to Earth in 5 years. It glimmers with minus 2nd magnitude, appears 46 arc-seconds in size but only 7º high. It is best observed at 12:52 AM. The giant planet, even at its highest, is so low that one rarely sees steady images in the telescope. Jupiter is retrograding (heading West) above Scorpius. Jupiter’s Great Red Spot, a giant storm, can be telescopically spotted at 3:07 AM on Wednesday. Also, on Wednesday the Moon Io begins to cross Jupiter’s face at 12:33 AM, followed by Io’s shadow at 12:36, followed by Ganymede exiting Jupiter at 1:40 AM and finally Ganymede’s shadow also exiting at 1:54 AM. This is its second double shadow transit in a week; a rare observing event. Jupiter sets at 5:25 AM.

Dwarf Planet 1Ceres also inhabits Ophiuchus, about 12º to Jupiter’s upper right. It shines with 7th magnitude but is a tiny 0.7 arc-seconds in size and 26º high. It rises at 7:09 PM and sets at 4:48 AM. Finder charts are available from magazines and online.

Saturn rises to the left of Sagittarius at 10:24 PM. It shines with zero magnitude, about 13º high at Midnight, and appears about a third of Jupiter’s size. Saturn is best observed at 3:00 AM.

Three planets appear in the pre-sunrise East. Neptune rises first in Aquarius at 1:15 AM, glowing with 8th magnitude, 2 arc-seconds in size and 18º high by Dawn. Uranus rises in Aries at 2:59 AM, shining with 6th magnitude and 3 arc-seconds, and 18º high. Venus brings up the rear by rising in Taurus. It appears about 95% lit, glistening with minus 4th magnitude and appearing 10 arc-seconds. However, it is only 3º high at Civil Dawn. All three pose a challenge for the sky-watcher, because of the rapidly brightening sky.

The dim constellation Virgo lies below Leo’s tail. Its brightest star, Spica, is not bothered by lunar glare. Virgo and Spica are ancient, known to all early civilizations, and studied for millennia. It is almost exactly first magnitude and one of the closest to Earth. In 1890, examination of Spica’s light revealed an unseen companion. A little-known space probe has changed our view of Spica. MOST, a satellite that studies variable stars, revealed that Spica is an eclipsing binary. In other words, two stars – one large and one smaller – eclipse each other every four days. The dimming is very slight. The brighter star itself varies. They are so close that they are egg-shaped, not oval. These discoveries reveal the main star’s diameter and set an upper limit on its size. At 260 light years away, Spica is an example of a star likely to go supernova – blow itself up – in the not too distant future.

Skywatch Line for Friday, June 7 through Sunday, June 9, 2019

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

On Friday, Sun rises at 5:18am and sets at 8:32pm; the waxing crescent Moon rises at 9:33am. On Saturday and Sunday nights use the Moon to find Regulus, the brightest star in the constellation Leo, the Lion. This blue-white star is of 1st-magnitude brightness and is the 21st brightest star. The Moon is close to Regulus for only a few days each month. When the Moon is no longer there to guide you, use the Big Dipper to guide to this star. The two bowl stars on the handle side of the Big Dipper point to Regulus.

Only two of the five naked-eye planets are in good position for telescopic inspection. The other three hug the horizon. Low in the west at dusk you’ll find Mercury and Mars. Mercury, at magnitude –0.6, rises six degrees above the west-northwest horizon 45 minutes after sundown. Its sets a few minutes after 10pm. Mercury is starting its second evening apparition of this year. Mars glows at magnitude 1.8 as it slowly makes its way eastward through Gemini. Mars sets roughly two hours after the Sun. Jupiter reaches opposition on Monday. Which means it’s up all night. This weekend offers a great opportunity to enjoy Jupiter at its best. Jupiter, at magnitude –2.6 at the eastern leg of constellation Ophiuchus, presents the maximum amount of detail when its altitude is better than at least 15 degrees. Your best observing window runs from roughly 10:30 to 3:30am. Saturn rises shortly after 10:30pm. The best time to view Saturn and its magnificent rings in a scope is a little before 3:30pm, when the planet is highest. Saturn, at magnitude 0.2, is easy to identify as the brightest dot of light in eastern constellation Sagittarius. Venus, at magnitude –3.8, rises less than an hour before the Sun and hovers barely above the east-northeast horizon in bright twilight.

Globular cluster M5, in the constellation Serpens Caput, is one deep-sky object that is currently well positioned. M5 is the westernmost point in an equilateral triangle that also includes the stars Alpha (α) and Mu (μ) Serpentis. M5 holds the distinction of being the brightest globular cluster in the northern sky. The Serpens cluster is an easy binocular target, though the low magnification, typical of binoculars, makes all but a few globulars appear nearly stellar. M5 lies next to a similarly bright star, 5th-magnitude 5 Serpentis. In a telescope M5 is a splendid sight, and the greater the aperture, the better the view. The cluster’s luminous, tightly packed central knot is enveloped in a spherical swarm of faint stars. Some amateur observers consider M5 the finest globular cluster north of the celestial equator for small telescopes, even better than the celebrated M13, the Great Hercules cluster.

This Friday marks the 91st birthday of Bernard Flood Burke, the American astronomer who co-discovered that planet Jupiter emits radio waves. In 1955, Burke and Kenneth L. Franklin, at the Carnegie Institution in Washington, were scanning the sky for radio waves from galaxies. By chance, they found a radio signal that resembled short bursts of static, similar to interference by lightning on home radios. After weeks of study, finding the signals were periodic, four minutes earlier each day, they pinpointed Jupiter as the source. This was the first time radio sounds from a planet in our solar system been detected.

Skywatch Line for Wednesday, June 5th, and Thursday, June 6th, 2019

This is the Dudley Observatory Skywatch Line for Wednesday, June 5th, and Thursday, June 6th, Written by Loui Suarato.

The 9% illuminated, waxing crescent Moon follows Mars into the west-northwestern horizon, and sets at 9:50 Wednesday night. The Gemini twins, Castor and Pollux, trail the Moon. Jupiter rises at 8:41 p.m. in the constellation Ophiuchus. Saturn rises two hours later in Sagittarius. At 43 minutes past midnight on Thursday, Jupiter’s moon Europa begins to be eclipsed by the planet. Europa will reappear at 3:43 Thursday morning. If you would like to follow the various transits, eclipses, and occultations of Jupiter’s moons, you can obtain the phone app, Jupiter’s Moons developed by Sky & Telescope. In addition to the various events of the day, the Jupiter’s Moons app also provides a simulated chart of the Galilean moons’ movements over time. A transit occurs when one or more of the Galilean moons, or their shadows cross between the planet and Earth’s point of view. A Jupiter moon is eclipsed when passes through the planet’s shadow, temporarily obscuring it. Jupiter’s Moons can also be hidden by other Moon’s shadows. An occultation occurs when one object is covered by another. Most occultations result from Jupiter moving in front of its moon, seen from Earth.

June 5 is the 200th anniversary of the birthdate of astronomer John Couch Adams. Born in the United Kingdom in 1819, Adams was famous for predicting the existence and location of Neptune. Adams’ coordinates, and those made independently by Urbain Le Verrier, were sent to Johann Gottfried Galle, who made the visual discovery at the Berlin Observatory. These nights, Neptune can be found between the constellations Pisces and Aquarius, rising after 2 am. Adams also correctly determined that the orbits of a comet and the Leonid meteor shower were similar and, therefore, connected. The comet would later be known as Tempel-Tuttle.

Skywatch Line for Monday and Tuesday, June 3rd and 4th, 2019

This is the Skywatch Line for Monday and Tuesday, June 3rd and 4th, written by Joe Slomka.

The Sun sets at 8:28 PM; night falls at 10:40. Dawn begins at 3:06 AM and ends with the Sun rising at 5:18.

Mars is no longer the only planet in the evening sky. The Red Planet, Mercury and the stars of Gemini all appear together this month. Mars appears about 98% illuminated, shines with 2nd magnitude, but is only 15º high in the West. Mercury makes a temporary visit to the evening sky by occupying Taurus, appearing 80% lit, but glowing with minus zero magnitude. While Mars becomes more difficult daily, Mercury, 12º below Mars, actually gets better for the first half of June. Mercury sets at 9:48 PM, Mars at 10:41 PM.

The Moon turns “New” on Monday, which means we do not see it. Tuesday’s 2-day-old Moon occupies Gemini, appearing a slim 3% lit, 7º high and 6º to Mercury’s lower left. The Moon sets at 9:54 PM.

Jupiter rises in the eastern constellation of Ophiuchus at 8:51 PM. It blazes with minus 2nd magnitude and appears 45 arc-seconds in size. By twilight’s end, it is higher at 14º. The controversial Great Red Spot can be telescopically observed at 2:22 AM, Wednesday morning. Tuesday finds the moon Ganymede’s shadow ending its crossing of Jupiter’s face at 9:55 PM, but Ganymede begins its crossing at 10:23 PM. A few minutes later, the moon Io ends its shadow crossing at 10:42 and Io’s crossing at 10:49. Such Double Shadow Transits are quite rare and always a treat for visual telescopic astronomers.

Dwarf Planet 1Ceres shares Ophiuchus with Jupiter. It glows with 7th magnitude but exhibits a tiny 0.7 arc-seconds in size. It rises and joins Jupiter in an all-night excursion, beginning at 7:43 PM and is best observed at 12:33 AM. Finder charts are available from various astronomy websites.

Saturn, 29º to Jupiter’s lower left, rises in Sagittarius at 10:53 PM. It shines with zero magnitude and appears about a third of Jupiter’s size near Sagittarius’ Teapot. It is brightening in preparation for its July Opposition. Saturn is best seen at 3:30 AM.

Neptune rises, at 1:42 AM, in Aquarius, glowing with 8th magnitude and appearing 2 arc-seconds in size, but 14º high. By Sunrise, it is about 29º high. Again, finder charts assist the early bird star gazer.

Uranus rises in Aries at 3:25 AM, shining with 6th magnitude, 3 arc-seconds in size and 13º high. Venus, rising in Taurus at 4:22 AM blazes with minus 4th magnitude, appearing about 95% lit, 10 arc-seconds in size and a meager 3º high. Both planets are difficult to find in the rapidly brightening Dawn sky and pose a challenge.

Thursday is the 75th anniversary of the Normandy Invasion that eventually ended the European Theater of WWII. General Eisenhower, overall commander, required a set of astronomical conditions for the invasion: lunar phase, tides and sunrise. The Moon on the night of June 5/6 was 99% lit, but only 23º high. This enabled airborne troops to land and attack. It also enabled battleships and cruisers to locate and bombard German shore positions before assault troops hit the beaches. More importantly were tidal considerations. Twice a day the Normandy tides rose 19 feet from low to high. Low tide was at 5:23 AM; shelling began at 5:50 and the Sun rose at 5:59. The first wave arrived at 6:30. Low tide was preferred because the enemy seeded the shoreline with obstacles and explosives. After the first wave landed, explosive demolition teams were to clear these obstacles, however rapidly rising water made their efforts difficult. The ocean was rising at a rate of one foot per 10 minutes. Many traps went undamaged. In addition, landing craft had to evade other hazards: piles driven into the shore with mines that would explode if a landing craft hit it. Despite hazards and fierce opposition, the allied forces made progress and drove the enemy from the beaches to make a slender toe-hold on the French coast.

Skywatch Line for Friday, May 31 through Sunday, June 2, 2019

This is Dudley Observatory’s Skywatch Line for Friday, May 31 through Sunday, June 2, written by Sam Salem.

On Friday, Sun rises at 5:21am and sets at 8:27pm; the waning crescent Moon rises at 4:00am and sets at 5:29pm. On Saturday morning, the very thin waning crescent Moon and Venus have a low-lying conjunction at dawn. The Moon sits a little more than six degrees to the right of Venus. The objects are less than 10 degrees up by sunrise. You need an unobstructed east-northeast horizon and binoculars to view the conjunction. The new Moon occurs on Monday at 6:02am.

Mars sets around 11:45pm and Jupiter rises a few minutes after 9pm. By 10pm, Mars and Jupiter are both hovering only a few degrees above the horizon. Face west-northwest to spot Mars, glowing at magnitude 1.8 in constellation Gemini. Turn around to face the opposite direction and you’ll find Jupiter gleaming at magnitude –2.6 in the southeast. The two planets are opposite in the sky and they’re at opposite stages in their respective apparitions. Mars is slipping away, while Jupiter is nearing opposition. Jupiter climbs to its highest point around 1:30am, when it’s due south and ideally placed for telescopic inspection. Saturn rises in the east-southeast horizon a little after 11pm. Saturn, at magnitude 0.3, sits in eastern Sagittarius, and culminates shortly after 3:30am. Venus, at magnitude –3.8, rises less than an hour ahead of the Sun.

The dwarf planet Ceres reached opposition this week, which means it’s visible most of the night. At opposition, Ceres is closest to Earth and at peak brightness. Use this moonless weekend to observe the dwarf planet. Ceres appears as a 6.9-magnitude point of light in northern Scorpius, close to the border with Ophiuchus. The dwarf planet is near the meridian around 12:30am. The best way to locate your target is to use binoculars or a telescope at low power to scan west-northwest of 4th-magnitude Chi (χ) Ophiuchi. Use the method Giuseppe Piazzi used to be sure you have spotted Ceres, and not just a field star. Note your suspect’s position over a period of two or three nights. If it moves relative to the background stars. Then, you’ve found Ceres. When Giuseppe Piazzi discovered Ceres in 1801, he believed he had found a comet. Later, Ceres was thought to be the long-searched-for planet expected to circle the Sun between the orbits of Mars and Jupiter. When similar objects started turning up in the same zone, astronomers realized they had stumbled across a whole new class of solar system object. These bodies were called “minor planets” or “asteroids”. In 2006, Ceres was reclassified as a “dwarf planet”.

If you have a dark sky, you’ll be able to pick the constellation Draco, the Dragon, winding around the North Star, Polaris. The entire Dragon requires a dark sky to be seen. You’ll find the Big Dipper high in the north on June evenings. The two outer stars in the Dipper’s bowl point to Polaris, which marks the end of the Little Dipper’s handle. The Dragon winds between the Big and Little Dippers. A noteworthy star, Thuban, in constellation Draco is easy to find by looking between the Dippers. Although it’s not a super bright star, it is bright enough to see with relative ease on a dark night. Star-hop to Thuban from the Big and Little Dippers. Draw an imaginary line that connects the stars Pherkad, in the Little Dipper, and Mizar, in the Big Dipper. You’ll see Thuban midway between these two guide stars. Thuban is famous for having served as a pole star around 3000 B.C. There are two more prominent stars to look for in the Dragon. These stars are Eltanin and Rastaban. They lie in the head of Draco. They represent the Dragon’s Eyes. They’re noticeable because they’re relatively bright and near each other. The Dragon’s Eyes are near the blue-white star Vega. In Arabic, “Thuban” means “a snake”, “Eltanain” means “a dragon”, and “Rastaban” means “snake’s head”.

Skywatch Line for Wednesday, May 29th, and Thursday, May 30th, 2019

This is the Dudley Observatory Skywatch Line for Wednesday, May 29th, and Thursday, May 30th, written by Louis Suarato.

The 20% illuminated, waning crescent Moon sets at 3:22 Wednesday afternoon. Sunset occurs at 8:24 p.m.. Civil twilight, when the Sun is 0 to 6 degrees below the horizon, and only the brightest stars and planets can be seen, begins at sunset and ends at 8:58p.m… Nautical twilight, when the Sun is between 6 and 12 degrees below the horizon, and stars can be utilized for nautical navigation, begins at 9:41 p.m.. Astronomical twilight, when the Sun is 12 to 18 degrees below the horizon, and most celestial objects can be seen, begins at 10:28 p.m.. Jupiter rises at 9:12 p.m., and Mars sets about an hour and half later. Jupiter’s moon, Europa, disappears behind the gas giant at 10:07 Wednesday night, and reemerges at 1:08 a.m., Thursday. The last naked eye planet to appear is Saturn, rising at 11:17 p.m.. Saturn’s rings are currently tilted at 23.7 degrees toward Earth, and are beginning to open toward their widest, 27 degrees, in September. Saturn will reach opposition on July 19 this year.

On May 20, 1971, the U.S. Mars space probe launched from Cape Kennedy, Florida. The space probe was equipped with cameras, infrared spectrometer and radiometer, ultraviolet spectrometer, radio occultation and celestial mechanics instruments. The Mars probe entered orbit on November 13 of that year, becoming the first artificial satellite of Mars. Its photos completed a 100% survey of the Martian surface, including volcanos and a 3,000 mile canyon. The space probe also provided the first close-up images of the Martian moons, Phobos and Deimos.

The rocket manufacturer, SpaceX, recently deployed the first 60 satellites of 12,000 they plan to release into the mid-2020’s. These satellites are designed to implement a new space-based internet.. The train of satellites are currently orbiting Earth at about the same altitude as the International Space Station, and are being viewed and imaged by amateur astronomers. To check on passes over our region, go to the website calsky:

Skywatch Line for Monday (Memorial Day) and Tuesday, May 27th and 28th, 2019

This is the Skywatch Line for Monday (Memorial Day) and Tuesday, May 27th and 28th, written by Joe Slomka.

The Sun sets at 8:23 PM; night falls at 10:34. Dawn begins at 3:14 AM and ends with the Sun rising at 5:22.

Mars, in Gemini, continues as the easiest evening planet. Appearing 97% illuminated and shining with first magnitude, the Red Planet appears about 4 arc-seconds in size about 18º high in the West. It sets at 10:50 PM. Mercury hovers in the western constellation of Taurus. It shimmers with minus 1st magnitude, but is only 1º altitude, requiring an unobstructed horizon to be spotted. Mercury sets at 9:01 PM, but becomes easier in June.

Jupiter rises in Ophiuchus at 9:22 PM, glowing with minus 2nd magnitude, appearing a large 45 arc-seconds and 9º high. Jupiter is causing excitement among amateur and professional astronomers. The Skywatch Line has long mentioned the Great Red Spot (GRS), a giant storm on Jupiter. May 19th, Australian astronomers reported 10 thousand Km pieces of the GRS detaching and being carried away and dissipated by a nearby jet every week or so. These jets blow at about 350 Miles Per Hour. Smaller similar events have happened before in 2017. The GRS has been shrinking for a while. Once 3 Earths wide, it now is only about the size of our planet. The GRS will be visible at 1:37 AM on Wednesday. Jupiter is nearing its June Opposition, which makes it ideal for amateurs with 6” or larger telescopes to follow this event. Astronomy websites are covering this event with regular updates. Jupiter sets at 1:55 AM.

Dwarf Planet 1Ceres shares Ophiuchus with Jupiter. Ceres experiences its own Opposition Tuesday night, making it the ideal time to examine this largest asteroid and brightest dwarf. Ceres is differentiated into layers; it has a rocky core, but icy crust and surface. It is about 25% ice. Ceres glows with 7th magnitude and is a tiny 0.7 arc-seconds in size, making observation easier for binoculars or small telescope. It rises at 8:16 PM and is best observed at 1:07 AM. Finder charts are available from various astronomical websites.

Saturn rises in Sagittarius at 11:22 PM. It shines with zero magnitude and appears about one-third Jupiter’s size. By midnight, is it only 5º high, but 24º at Dawn. It is best observed at 4:00 AM.

Blue-green Neptune rises in Aquarius at 2:10 AM. It smolders with 8th magnitude, appearing about 2 arc-seconds in size. Finder charts also assist in locating this distant member of our Solar System.

The waning Moon shares Aquarius with Neptune on Tuesday. At 24-days-old, it appears about 35% lit and blazing with minus 8th magnitude and rises at 2:44 AM. Wednesday, finds a slimmer Moon rising at 3:09 AM in Cetus. It is about 26% lit, and slightly dimmer. Wednesday’s Moon is found between Neptune and Uranus.

Uranus also shares Aquarius with Neptune and the Moon. Rising at 3:51 AM, it shines with 5th magnitude and is 9º high at Civil Dawn. Venus brings up the rear, in Aries. Rising at 4:26 AM, it appears about 93% lit and shines with minus 3rd magnitude, but only 3º above the eastern horizon. Both planets are rising in the increasingly sunlit eastern sky. Observers should try for them as early as possible.