Skywatch Line for Monday and Tuesday, April 24th and 25th, 2017

This is the Skywatch Line for Monday and Tuesday, April 24th and 25th.

The Sun sets at 7:48 PM; night falls at 9:35. Dawn breaks at 4:10 AM and ends with the Sun rising at 5:58.

Only two planets are visible in the twilight sky. Mars is moderately low in the western sky; at civil dusk, it is 18 degrees high and appears as a tiny first magnitude red dot in Taurus. Do not confuse Taurus’ red star Aldebaran for Mars. Mars sets at 10:11 PM.

Jupiter, in Virgo, is up moderately high in the eastern sky. It flashes at minus 2.4 magnitude and appears about 44 arc-seconds wide in our instruments. It rises at 6 PM and is best observed at 11:43 PM and sets at 5:27 AM. Jupiter’s moon Io presents an interesting set of appearances and occultations:
Tuesday, at 1:59 AM it is hidden by the planet and reappears at 4:36 AM; then at 11:17 PM it begins marching across Jupiter’s face, followed by its shadow at 11:42; Io exits the planet at 1:27 AM Wednesday, followed by its shadow at 1:53 AM.

Saturn rises shortly before Midnight in Sagittarius. It appears as a cream-colored orb just above the eastern horizon. In binoculars or telescope, it glows at zero magnitude and is 17 arc-seconds in size. Saturn is best seen at 4:30 AM, when it lies due South.

Venus rises in Pisces, in the East, at 4:23 AM. It blazes at minus 4.5 magnitude, is 11 degrees high at civil dawn and appears about 22 percent illuminated. The Moon is not visible because it is too close to the Sun and turns “New” Wednesday morning.

Last week, we discussed Saturn’s moon Iapetus; today, let us consider another Saturnian moon – Enceladus. Jupiter owns 67 moons; Saturn commands a fleet of 62 satellites, 8 of which are visible in amateur telescopes. Sir William Herschel discovered Enceladus in 1789 and named it for one of the mythical Giants that fought the Greek gods. Enceladus is medium sized, about 504 KM (313 mi) in diameter and orbits Saturn in 1.37 days. NASA’s Cassini space probe revealed an ice-covered world, with strange blue “tiger stripes.” Planetary scientists soon realized that there was an ocean beneath the ice. They also witnessed water spouting from those “stripes.” Like Jupiter’s moon Europa, Enceladus is being squeezed by Saturn’s huge gravity and heating up the interior, causing the venting. As the Cassini 12-year mission wraps up, NASA dared to have Cassini make close passes on several moons. A pass through Enceladus’ vapor revealed salt and silica nanoparticles, which were picked up by the water’s contact with hot interior rocks. Hot rocks should leach oxygen from seawater leaving molecular hydrogen. A recent flyby of Enceladus verified its existence. Molecular hydrogen creates a chemical imbalance that may be conducive to life. However, astrobiologists are not claiming life, but only the conditions that may make it possible.

Skywatch Line for Friday, April 21, through Sunday, April 23, 2017

This is Dudley Observatory’s Skywatch Line for Friday, April 21, through Sunday, April 23, written by Sam Salem.

On Friday, the Sun rises at 6:04am and sets at 7:45pm; the waning crescent Moon rises at 3:30am and sets at 2:16pm. Watch the razor-thin crescent Moon seven degrees below and to the right of Venuson Sunday morning, shorty before sunrise. Spot Venus close to the Moon even after the Sun comes up. Venus, at magnitude –4.7, transitioned from the evening to the morning sky about a month ago,around the time of the spring equinox. In a telescope, Venus looks like a waxing crescent, spanning 45 arc seconds, which is more than 10 times the current apparent diameter of Mars.

Jupiter, at magnitude –2.5, is visible all night long with its four bright moons. Saturn, at magnitude 0.3, rises around 12:30 am, and culminates around 5 am. Mars, at magnitude 1.6, sits low in the west during twilight. On Friday evening, Mars will have its closest approach to the Pleiades cluster in Taurus, low in the west at dusk.

On Saturday night, the Lyrid meteor shower peaks in the predawn hours. This meteor shower has been known to produce exceptionally bright meteors. Under good conditions expect to see as many as 10 to 20 meteors per hour in the few hours before dawn. The crescent moonlight shouldn’t interfere with Lyrid shower. The radiant point of the Lyrid meteor shower is near the bright star Vega in the constellation Lyra, the Harp. Vega rises over the northeast horizon by around mid-evening, moving high overhead just before twilight. The best viewing of this shower is usually during the few hours before morning dawn. The Lyrid meteor shower has the distinction of being among the oldest of known meteor showers. The ancient Chinese are said to have observed the Lyrid meteors “falling like rain” in the year 687 BC. Comet Thatcher is the source of the Lyrid meteors. Every year, in the later part of April, Earth crosses the orbital path of Comet Thatcher (C/1861 G1). The Comet last visited the inner solar system in 1861. It is expected to return in 2276. Meteors are seen when Earthpasses through thick clump of comet rubble. Pieces shed by the comet bombard the Earth’s upper atmosphere at 110,000 miles per hour.

The world celebrates the Earth Day on Saturday. http://www.earthday.org/. This year, Earth Day Network and the March for Science are co-organizing a rally and teach-in on the National Mall in Washington, D.C. Using the teach-in concept deployed for the very first Earth Day in 1970, the rally and teach-in on the National Mall will focus on the vital role science plays in our democracy and the need to preserve this role. More than 1 billion people now participate in Earth Day activities each year, making it the largest civic observance in the world.
The March for Science Albany takes place at New York Capitol Building. Dudley Observatory and miSciwill be participating in the Family science activities. http://www.albany.com/event/march-for-science-144346/.

Skywatch Line for Wednesday, April 19th, and Thursday, April 20th, 2017

This is the Dudley Observatory Skywatch Line for Wednesday, April 19th, and Thursday, April 20th, written by Louis Suarato.

The Moon reaches its Last Quarter phase at 5:57 a.m.,Wednesday. The Last Quarter Moon will set at 14 minutes past noon later that day. The Moon will rise as a waning crescent at 2:52 a.m., Thursday. After sunset, Mars will be setting within the constellation Taurus. Look for the Pleiades about 4 degreesto Mars’ upper right. The red planet and star cluster may be seen in the same field of view through binoculars or a small telescope. Jupiter rises at 6:25 p.m. in the constellation Virgo and will remain in the sky until setting at 5:45 a.m. Thursday. At 9:10 p.m. Wednesday, Jupiter’s moon Io will reappear from eclipse. Saturn rises at 18 minutes past midnight Thursday, above the Teapot asterism in Sagittarius. Venus rises at 4:38 a.m. Thursday in the constellation Pisces, joining the crescent Moon and Saturn in the pre-dawn sky. Mercury is at inferior conjunction, between Earth and the Sun, and will join Venus and Saturn as morning planets at the end of the month.

Comet 41P/Tuttle-Giacobini-Kresak is now at 6th magnitude. At midnight, Comet 41P can be found about 40 degrees above the northeastern horizon, and 17 degrees to the upper right of Lyra’s brightest star, Vega. More precisely, the comet is located 2 degrees east of the star, Pastaban in the constellation Draco. To the comet’s right is the Great Square in Hercules. Look for the Great Cluster in Hercules, globular cluster M13, along the line connecting the two top stars, closer to the northernmost star, at the top of the square.

The Albany Area Amateur Astronomers invite you to join them at their monthly meeting to be held at miSci in Schenectady this Thursday night at 7:30. This month’s speaker is RebeccaKoopmann, Professor and Chair, Department of Physics and Astronomy, Union College. She will be discussing Exploring Galaxy Evolution and Large Scale Structure with theUndergraduate ALFALFA Team. The NSF-sponsored Undergraduate ALFALFA (Arecibo Legacy Fast ALFA) Team (UAT) is a consortium of 20 institutions across the U.S., founded to promote undergraduate research and faculty development within the extragalactic ALFALFA HI blind survey project and follow-up programs. Koopmann will summarize the UAT program and discuss results from two ongoing collaborative research projects: (1) the UAT Groups project, a coordinated study of gas and star formation properties ofgalaxies in and around 36 nearby clusters, and (2) the Arecibo Pisces Perseus Supercluster Survey(APPSS), a project tomeasure in fall of galaxies onto the Pisces Perseus filament to determine for the first time the mass over density of a supercluster.

Skywatch Line for Monday and Tuesday, April 17th and 18th, 2017

This is the Skywatch Line for Monday and Tuesday, April 17th and 18th.

The Sun sets at 7:40 PM; night falls at 9:24. Dawn breaks at 4:25 AM and ends with the Sun rising at 6:08.

The evening sky has two bright planets, Mars, in Taurus, in the West and Jupiter in the East. Mars shines at first magnitude moderately high in the western sky, appearing as a tiny red dot. Note Mars’ position. As the sky darkens, Mars lies about 4 degrees below the Pleiades star cluster. This juxtaposition remains for the next 5 nights. Both set by 10:14 PM.

Jupiter rises at 6:31 PM in Virgo. It flashes at minus 2.5 magnitude, is 16 degrees above the horizon and appears 44 arc-seconds in size. Jupiter continues to shy away from Spica, Virgo’s brightest star. While binoculars afford views of the giant planet, telescopes provide greater details. The Great Red Spot, a giant storm, is visible at 9:09 PM on Monday and 2:56 AM on Wednesday. The Jovian moon Io disappears behind Jupiter at 12:15 AM on Tuesday and reappears at 2:41 AM. It also begins to cross Jupiter’s face at 9:32 PM on Tuesday, followed by its shadow at 9:48 PM; Io leaves Jupiter at 11:43 PM also on Tuesday, followed by its shadow at 11:59 PM. Jupiter is best observed at 12:19 AM and sets at 5:57 AM.

Saturn rises in Sagittarius at 12:24 AM, glowing at zero magnitude and appears 17 arc-seconds in size. Best views of Saturn are at 4:58 AM. The cream-colored planet is obvious. Besides the rings, Saturn has sixty-one moons. One of these, Iapetus, has puzzled observers for centuries. Iapetus is bright when it is on one side of Saturn, but markedly darker on the other.

Astronomers think they have figured it out. Iapetus is tidally locked to Saturn, just like the Earth’s Moon – showing the same side to the planet. The leading side of Iapetus sweeps up debris from a newly discovered (and invisible to amateurs) ring. Thus, one side looks like it was covered in chocolate dust, while the trailing side is as white as snow, really ice. In addition, the dust, warmed by sunlight, melts the ice below, which flows to the trailing side and re-freezes. Iapetus has a 79.3-day orbit, and is visible in amateur telescopes. Astronomy programs and websites assist the observer.
The Moon shares Sagittarius with Saturn, and rises an hour after the Ringed Planet. The 21-day-old Moon blazes at minus 10th magnitude, appears about 60 percent illuminated and rises at 1:27 AM Tuesday and 2:11 AM on Wednesday, when it becomes Last Quarter.

Venus rises in Pisces at 4:40 AM, also in the East. It flashes at minus 4th magnitude, appears 46 arc-seconds in size and is 15 percent illuminated. At the same time, Comet PanSTARRS is also visible in the eastern sky, in Aquarius. Reports are that it went from 8th magnitude to 6th magnitude, within binocular visibility. PanSTARRS may even brighten more, since it is nearing perigee (near Earth) on April 19th. However, this becomes a challenge object, since it is in a rapidly brightening dawn sky.

Skywatch Line for Friday, April 14, through Sunday, April 16, 2017

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

On Friday, Sun rises at 6:15am and sets at 7:37pm; the Waning Gibbous Moon sets at 8:24am and rises at 10:56pm, reaching transit altitude of 32 degrees south at 3:14am.

On Friday, mid-to-late evening, catch the Moon rising above the eastern horizon. Stay later to watch Saturn follow the Moon into the sky by very late evening, or after midnight. Look for the Moon, the star Antares and Saturn in the predawn and dawn sky for the next several mornings. Best view of the Moon and Saturn is in the predawn sky on Saturday night as the Moon and Saturn move highest in the sky near dawn time. Observe Saturn just before the onset of morning twilight, around 5:30 am, when it’s highest. Saturn will lie less than 25 degrees above the southern horizon. With the ring system currently tilted open, almost the maximum amount, it’s easier to spot the famous Cassini Division, the gap that separates Saturn’s two brightest rings.

Jupiter is seen in the western sky during the predawn hours, while Venus lurks low in the east as darkness begins to give way to dawn. Jupiter, at magnitude –2.5, is now past opposition, therefore, it’s up slightly before sunset and viewable all night long. It is the first bright object to pop out into the eastern sky at dusk. Inspect Jupiter with a telescope when it’s up in the sky after midnight.

Let the blue-white star Spica guide you to the Omega Centauri star cluster. This year, Spica will be easy to find because planet Jupiter is quite close to this star. Omega Centauri star cluster climbs highest up for the night with Spica. The cluster can be seen with the unaided eye, if sky is dark enough and if you’re far enough to the south. Omega Centauri is the largest and finest globular star cluster visible to the eye alone. Very few of the Milky Way galaxy’s globular star clusters are readily visible without optics. Omega Centauri looks like a fairly faint fuzzy star. Globular clusters are large, symmetrically shaped groupings of stars, fairly evenly distributed around the core of our Milky Way galaxy. Omega Centauri is best seen through a telescope. It will be seen as a globe-shaped stellar city with millions of stars.

Friday marks the birthdate of Christiaan Huygens. Born on April 14 1629, the Dutch physicist and astronomer founded the wave theory of light and discovered the true shape of the rings of Saturn. Using a lens he ground for himself, he discovered the first moon of Saturn, later named Titan. Huygens also studied and drew the first maps of Mars. On January 14 2005, a NASA space probe, named after Huygens, landed on Titan.

Skywatch Line for Wednesday, April 12th, and Thursday, April 13th, 2017

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

Wednesday’s twilight features Mars setting in the west as Jupiter rises in the east. The face of Mars is 97% illuminated, while Jupiter is 100% illuminated. Mars has two small moons, Phobosand Deimos, which are among the smallest in the solar system. Jupiter has 67 moons, four, known as the Galilean moons, are among the largest in the solar system. Mars’ atmosphere consists mainly of nitrogen and argon, while Jupiter’s atmosphere is comprised mostly of hydrogen and helium. Mars’ temperature ranges from 70°F to -225°F. The temperature of Jupiter’s outer clouds is estimated to be -234°F. Jupiter’s core temperature is estimated to be as hot as 43,000°F, hotter than the surface of the Sun!

The 97% illuminated, waning gibbous Moon rises at 9:01 p.m. in the constellation Libra, followed by Saturn at 50 minutes past midnight. Venus joins Saturn and Jupiter as morning planets when it rises as an 11% illuminated crescent at 4:57 a.m.,Thursday. By the end of April, Venus’ phase will increase to 26%. Venus rises as Jupiter sets, and the two brightest planets will embellish opposite horizons. Venus brightens from -4.2 magnitude on April 1st to -4.7 magnitude on April 30th.

April 12th is the anniversary of the first human in space. In 1961.Yuri Gararin became the first human to orbit the Earth when his spacecraft, the Vostok 1, completed one orbit around Earth. Since then, there have been 315 manned space missions, 139 by the Soviet Union/Russia, 171 by the United States, and 6 by China. Including Gagarin, there have been 549 people who have completed at least one Earth orbit. The total time by humans in space is in excess of 136.6 human-years.

Skywatch Line for Monday and Tuesday, April 10th and 11th, 2017

This is the Skywatch Line for Monday and Tuesday, April 10th and 11th.

The Sun sets at 8:32 PM; night falls at 9:13. Dawn breaks at 4:39 AM and ends with the Sun rising at 6:20.

Civil Dusk presents two planets at each horizon. Mercury hovers 11 degrees above the western horizon; it shines at minus 2nd magnitude, appears about 11 percent illuminated and is a tiny 10 arc-seconds in size. Mercury is stationary tonight; Tuesday begins a descent into the Sun’s glare. It sets at 8:48 PM. Mars lies 18 degrees to Mercury’s upper left in Aries. Mars is brighter at magnitude 1.5, but smaller in our telescopes and sets at 10:10 PM.

Meanwhile, the nearly full Moon and Jupiter occupy the eastern sky and the constellation Virgo. Monday’s Moon rises 7:03 PM and blazes at minus 12.3 magnitude. Tuesday, the Moon is officially Full at 2:08 AM and sets at 6:49 AM. Wednesday it sets at 7:19 AM. The Moon’s glare blinds us to all but the brightest objects. Jupiter, only 2 degrees away, is one of them. It shines at minus 2.5 magnitude. Jupiter just passed Opposition on Friday, which means it stays up nearly all night. Telescopic observers can see the planet’s Great Red Spot at 8:24 Monday night and at 2:10 AM on Wednesday. They can also witness the Jovian moon Io disappear behind the planet at 10:31 PM on Monday and see it reappear at 12:47 AM Tuesday.

Saturn rises at 12:52 AM in Sagittarius. It is moving retrograde (westward) this month. Saturn shines at 0.4 magnitude, appears 17.3 arc-seconds in size and is almost “full.” Saturn is best observed at 5:26AM.

Venus returns to visibility in the pre-dawn sky. It rises in Pisces at 5:00 AM, blazes at minus 4.4 magnitude, 51.7 arc-seconds in size, is about 10 percent lit and floats about 8 degrees high.

By nightfall, both Orion and Canis Major, the mighty hunter and his dog, are well up. The distinct star pattern guaranteed that Orion would be considered a god, hero, or both. Orion was so good a hunter that the gods feared he would exterminate all the animals. The stealthy Scorpion was sent to sting and kill Orion. The gods repented right after Orion’s death. So, they placed him in the sky, along with his faithful dog. However, the gods also placed the Scorpion in the sky, but at opposite ends. So, the constellation Scorpius sets as Orion rises.

The four bright stars that mark his shoulders and knees, the three stars that signify his belt, and the fuzzy spot that denotes his scabbard easily identify Orion. That fuzzy spot is now known as the Great Orion Nebula. In amateur telescopes, it appears as a gray cloud. But that cloud is special; it is a stellar nursery. As we watch, clouds of gas and dust are condensing, causing pressures and igniting nuclear fires.

Skywatch Line for Friday, April 7, through Sunday, April 9, 2017

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

On Friday, Sun rises at 6:27am and sets at 7:29pm; the 87% illuminated Waxing Gibbous Moon sets at 4:49am and rises at 3:49pm. On Friday evening, the waxing gibbous Moon passes just one degree south of Regulus, the brightest star in Leo. The Moon will be closest to Regulus around 12:40am. On Sunday night, the almost full Moon is coming closer to planet Jupiter. Watch the Moon moving closer to Jupiter in the next nights as the full Moon and Jupiter move in front of the constellation Virgo. Full Moon occurs on Tuesday at 2:08am.

Spot Mars, at magnitude 1.5. The red planet hangs 20 degrees above the horizon at dusk. Mercury, at magnitude 1, sits just eight degrees high 45 minutes after sunset. Saturn rises around 2:00am and reaches the meridian at 6:00am as twilight increases. Venus, our newly “morning star” clears the east horizon almost an hour ahead of the Sun. At magnitude –4.4, Venus is easily seen even in twilight. Venus’ morning apparition will last through to the end of the year.

Jupiter rises towards the east at sunset, at magnitude –2.5, dominating the entire sky. Earth passes between the Sun and Jupiter, placing Jupiter opposite the Sun in our sky on Friday at 6:00pm. This means that Jupiter will be up all night at its brightest for this year. Jupiter now rises in the east around sunset, climbs highest in the sky at midnight and sets in the west around sunrise. Jupiter moves in front of the constellation Virgo, the Maiden. The closest first magnitude star to Jupiter is Spica, the brightest star in Virgo. Jupiter comes to opposition about every thirteen months.

This year, the Sun enters the constellation Virgo on September 16 and leaves Virgo on October 31. Constellation Virgo is lost in the sun’s glare at this time of year. April is a much better time of year for viewing the constellation Virgo than in September and October. The bright Moon passing in front of Virgo for the next several days will make it difficult to see the starlit figurine of Virgo, the Maiden right now. The Moon will drop out of the evening sky in a week, giving a chance to better observe the stars of constellation Virgo and planet Jupiter.

On April 9 1895, American astronomer James Keeler proved that the rings of Saturn were composed of meteoric particles, as predicted by James Maxwell. Keeler’s spectrogram of light reflected from Saturn’s rings showed a Doppler shift indicating a variation in radial velocity. Thus, particles in the inner part of a ring, closer to Saturn, move at a different rotational speed from those in more distance parts of a ring.

Skywatch Line for Wednesday, April 5th, and Thursday, April 6th, 2017

This is the Dudley Observatory Skywatch Line for Wednesday, April 5th, and Thursday, April 6th, written by Louis Suarato.

The 71% illuminated, waxing gibbous Moon rises at 1:51 p.m. Wednesday. By nightfall, you’ll find it high above the southern horizon, in the constellation Cancer, to the lower left of M44, the Beehive Cluster. Thursday, Leo’s brightest star, Regulus, will shine less than a degree to the left of the Moon. Look for Mars and Mercury low in the west after sunset. Later in the evening, you’ll notice the Pleiades star cluster above Mars. Mercury, the lower of the two, will be 10 degrees above the horizon at 8 p.m., while Mars will be 23 degrees above the horizon to its upper left. Mercury will return as a morning star by month’s end. Jupiter rises at 7:29 p.m. in Virgo. Jupiter is approaching opposition, its point in the sky directly opposite the Sun, illuminating the entire face of the planet. Opposition occurs at 10 p.m. on Friday. Saturn rises at 1:14 a.m. Thursday. Saturn becomes stationary at 5 a.m. Thursday, and begins its retrograde motion thereafter. This illusion is caused by a faster Earth in orbit passing slower Saturn in its orbit. Instead of approaching Saturn, Earth passes it, and Saturn begins to move in the opposite direction in our sky.

The axial tilt of Earth not only affects our seasons, it also affectshow we view the circumpolar constellations. When looking up at Polaris, the North Star, we notice five constellations circling the star. In the northern hemisphere, these five constellations are Ursa Major, Ursa Minor, Draco, Cepheus, and Cassiopeia. From our latitude, these constellations never rise or set, and are viewable throughout the night. As Earth orbits the Sun, and our seasons change, the axial tilt provides us with a different angle of view toward these constellations in relation to the North Star. An example of this celestial seasonal clock can be explained using the Big Dipper asterism within the circumpolar constellation, Ursa Major. One can determine the season, by the Big Dipper’s position in relation to the North Star at nightfall. During the winter months, when the northern hemisphere is tilted away from the Sun, the Big Dipper stands straight up on its handle to the right of Polaris. During the summer, when the northern hemisphere is tilted toward the Sun, the Big Dipper appears on the opposite side of Polaris, vertical, with its bowl lower than its handle. During the Fall, when Earth is neither tilted toward, nor away from the Sun, the Big Dipper appearsbelow Polaris, horizontal along the horizon, with its bowl facing up, in the early to late evening. Likewise, during Spring, when the northern hemisphere is not tilted toward, or away from the Sun, but on the opposite side of the Sun than in the Fall, the Big Dipper lies horizontal, but above Polaris, with its bowl facing down.

Skywatch Line for Monday and Tuesday, April 3rd and 4th, 2017

This is the Skywatch Line for Monday and Tuesday, April 3rd and 4th.

The Sun sets at 7:24 PM; night falls at 9:02. Dawn breaks at 4:53 AM and ends with the Sun rising at 6:32.

The First Quarter Moon dominates the evening sky. By Civil Dusk, it is about 62 degrees high, in Gemini. It blazes at minus 10th magnitude, is half illuminated, is 32 arc-minutes large and is best observed at 7:16 PM. Tuesday finds it in Cancer and a bit larger, brighter and fatter. The Moon’s brilliance will hinder observation of dim distant deep space objects. The Moon sets at 2:44 AM on Tuesday and at 3:31 AM on Wednesday.

Three planets are visible in the evening sky. In the West, Mercury, in Aries, is about 12 degrees high and shines at 0.4 magnitude. Visible in binoculars, it is 8 arc-seconds in size and about one-third illuminated. It sets at 9:05 PM. Mercury is just past “greatest elongation,” which means it is at its best and brightest. Now is the time to observe Mercury before it starts fading and sinking into the Sun.

Mars lies 15 degrees to Mercury’s upper left. The Red Planet, also in Aries, glows at first magnitude and appears as a tiny red dot. It sets at 10:17 PM.

Jupiter, in Virgo, continues to creep away from the bright star Spica in preparation for its Opposition on April 7th. It shines at minus 2.5 magnitude and sets after Sunrise. Telescopic observers can see Jovian moon Io disappear behind the planet at 8:40 PM and reappear at 10:58 PM on Monday; they can also witness Ganymede be eclipsed at 12:38 AM and reappear at 3:14 AM on Tuesday. The Great Red Spot, a giant storm on Jupiter, is visible at 5:34 AM on Tuesday and at 1:25 AM on Wednesday.

Dawn finds Saturn already up in Sagittarius, having risen at 1:19 AM. At Dawn, it is 23 degrees high in the eastern sky and shines at zero magnitude. It is best observed just before daybreak at 5:44 AM. Its creamy white appearance makes identification easy and is always a joy to see its ring system.

Two weeks ago, Venus abandoned the evening sky; now it is beginning its “morning star” apparition. It rises in Pisces at 5:25 AM, about an hour before Sunrise. It blazes at minus 4th magnitude, appears about 4 percent illuminated and is about 6 degrees high in the East. Venus climbs higher and brighter as the month progresses.

When you are done observing Jupiter, turn your attention to the close star Porrima. The Latin name refers to the Goddess of Prophesy. The star lies midway between Spica, in Virgo, and Denebola, Leo’s tail. Porrima is a double star. Both stars are nearly identical. They are about the same brightness, third magnitude, and the same mass, about 1.5 times the Sun. They are sun-like, but significantly brighter and warmer. Like the Sun, Porrima and its companion are main sequence stars, fusing hydrogen into helium. Porrima was among the first double star systems discovered. Sir John Herschel calculated its orbit in 1833. They share a highly elliptical orbit, which make one cycle in about 169 years. An observer, with high power eyepieces in the telescope, can see them about 2.5 arc seconds apart.