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Regulars (Sky Watch by J. Alex Knoll)

There’s work overhead on the ISS

Thursday evening the waxing gibbous moon stands above the constellation Orion, appearing as if it were the hunter’s head in profile. The next night it is above and to the left of Betelgeuese, Orion’s shoulder, and the two form a nice line with Rigel, the hunter’s foot. Saturday Luna is below the twins of Gemini, Castor and Pollux, and above Procyon, the lead star in the constellation Canis Minor, the Little Dog. Off to the east is brilliant Jupiter. Sunday the moon rests in the middle of a triangle formed by Pollux, Procyon and Jupiter. Come Monday, Luna is just five degrees south of Jupiter. Tuesday the moon is to the upper right of Regulus, with Jupiter well above them both. Then on Wednesday, the moon, Jupiter and Regulus form a loose triangle.
    While the moon is our only natural satellite, countless manmade satellites orbit the earth. You’ve likely seen some and presumed they were airliners passing overhead in the night. The International Space Station, however, stands out from the pack, shining brighter than except the sun and moon and zipping across the sky like a shooting star.
    This past week, on February 21 and 25, astronauts aboard the ISS completed two of three scheduled space walks to prepare it for future commercial dockings. The third is planned for Sunday, March 1.
    The ISS was originally designed to receive docking space shuttles, which were secured alongside a berthing port using the station’s robotic arm. Unmanned cargo vessels and Russian Soyuz rockets (the only means of sending and retrieving astronauts to and from the station now that the shuttles have been retired) continue to use this system.
    However, manned commercial vessels, set to begin arrival to the ISS in 2017, will maneuver into a docking port within the station itself — something akin to what we’ve seen in movies and television for decades.
    The current system is a daunting and time-consuming process, both arriving and departing. The new system will allow a quick evacuation of crewmembers from the station in the event of an emergency.
    While we won’t be able to see the ISS during the space walk, it routinely flies overhead. For dates and times, go to http://spotthestation.nasa.gov.

Mars and Venus together at dusk

An ever-so-thin sliver of moon appears low in the west at evening twilight Thursday briefly before sinking beneath the horizon. The Evening Star Venus blazes above and to the moon’s left, with much fainter Mars just above Venus.
    Sunset Friday finds the two-day-old crescent moon within two degrees of Venus and Mars, all so close they easily fit within the eyepiece of binoculars and modest backyard telescopes.
    Come Saturday evening, the moon is roughly 10 degrees above Venus and Mars. But now the two planets are less than one-half degree of one another, with Mars just to Venus’s upper right. Venus shines more than 100 times as bright as Mars, so much so that its light could obscure the red planet, in which case you’ll need those binoculars to discern it. After that, Venus climbs higher into the west and away from Mars.
    While Venus and Mars appear together this week, the planets are actually millions of miles apart. Closer to the sun, Venus completes one orbit in roughly 225 days, while Mars makes the loop in 687 days. From our fixed vantage point here on earth — which isn’t really fixed, as we, too, are always in motion around the sun — these planets cross paths several times each year. But with roughly 75 million miles separating the orbital line of one planet from the other, there’s a lot of variance, so a close conjunction like this is pretty rare. Venus and Mars haven’t appeared so close in our sky since 2008, and they won’t again for another two years.
    Jupiter is a fixture of the night sky. It appears in the east as twilight fades, and by 11pm it is almost directly overhead. By 5am it is low in the west-northwest and sets just before sunrise.
    If you’re up before dawn, look for golden Saturn to the south. It is traveling with the constellation Scorpius, whose return to the skies each year heralds the coming of spring. The red heart of the scorpion, Antares, shines almost as bright as Saturn and less than 10 degrees below and to the left.
    The last of the naked-eye planets is just eeking away from the glare of the sun. Look for Mercury just above the east-southeast horizon in early dawn. Binoculars will help you pinpoint it against the glare of the coming sun.
    Wednesday’s first-quarter moon shines amid the constellation Taurus the bull and is less than one-half degree from its glaring red eye Aldebaran. Above the moon a little farther are the stars of the Hyades cluster, and higher still those of the Pleiades cluster.
    Some of the brightest stars appear during these cold, dark nights. Orion the hunter stands above the southern horizon in the evening, the three stars of his belt pointing up to Taurus and down toward Canis Major and the brightest star, Sirius. Orion’s foot is marked by Rigel, while his shoulder is the red giant Betelgeuse, with Canis Minor and its bright star Procyon to the left. Above these stand the Gemini Twins, Castor the higher and brighter star and Pollux a little below it. Above and to the right of Gemini is Capella, the bright star of Auriga the charioteer, shining directly overhead at 8pm. To the east is Leo the lion and its bright star Regulus.
    Just east of Orion is the winter Milky Way, stretching from the southeast to almost directly overhead and then down to the northwest in the early evening.

Join the fight for dark skies

The waning crescent moon rises ever later in predawn skies this week. Friday it appears before 3am, and by 5am it is well placed above the southeast horizon, forming a tight triangle with golden Saturn to the right and red Antares, the heart of Scorpius, below. The ringed planet stands above the scorpion’s head, one degree of its uppermost, second-magnitude star Graffias.
    By Monday the moon is a thin crescent low in the southeast at 6am. If skies are clear and you have an open view of the horizon, you might be able to catch the reappearance of Mercury. Your odds will be better with binoculars. Look to the lower left of the moon’s outside arc. The next morning, the last remnant of the waning crescent rises within an hour of the sun, and now Mercury is just a few degrees to the right of its inner curve.
    Mercury never pulls far from the sun and does not climb high into the sky. Plenty of people may not even realize they have seen it when looking at an exceptionally bright “star” hugging the horizon at dawn or during evening twilight.
    You shouldn’t be as hard-pressed to spot our neighbors, Venus and Mars in the west-southwest at dusk. The two are only five degrees apart at week’s end, well within the field of view of binoculars or a telescope. By Wednesday they’ve cut the distance by half on the way to a one-half-degree conjunction on the 21st. There’s no confusing the two, as Venus blazes at –3.9 magnitude, while Mars smolders at first magnitude. In the exponential calculus of stellar magnitude, that means that Mars, as bright as your average star, is 99 percent dimmer than the Evening Star.
    Jupiter is a fixture of the night sky right now, rising in the east-northeast as twilight fades, almost directly overhead at midnight and clinging to the west-northwest horizon as daybreak approaches. To its right is the dim constellation of Cancer the crab, while to its left is the easy-to-identify Leo the lion.
    This week marks the latest installment of the Globe at Night campaign. Its goal is for ordinary people to record and submit their star counts. The target this time around is the constellation Orion, which is high in the south by 8pm. You can download star charts and instructions at www.globeatnight.org. Your results along with thousands from around the world help astronomers measure darkness and raise awareness about the threat of light pollution.

Lovejoy awaits at the edge of sight

Lovejoy awaits at the edge of sight

The waning gibbous moon rises around 8pm Thursday, with Jupiter high above it. Between them is the blue-white star Regulus of Leo the lion. Sunday the moon rises around 11pm, with the white star Spica 10 degrees beneath it. As daybreak approaches Monday morning, the two are even closer together high in the southwest. That evening the moon rises just before midnight, and now it is the one trailing Spica. Before dawn Thursday the 12th, the now-crescent moon shines within 10 degrees of golden Saturn, with Antares, the red heart of Scorpius, a little farther toward the horizon.
    The waning moon leaves the evening sky bereft of its powerful glow, making these next two weeks your best chance to spot  Comet Lovejoy before it’s gone forever — or at least the next eight thousand years. The fifth magnitude comet hovers at the border of naked-eye visibility between the constellations Perseus and Andromeda.
    Binoculars will bring it into view as a faint, oblong smudge, while even a modest telescope will reveal its brighter coma and trailing tail. You might even be able to discern the green-glowing head of the comet and its blue-hued tail. These colors are a tell-tale sign of the comet’s molecular composition, the green from diatomic carbon and the blue from carbon monoxide, both being charged by interstellar ultraviolet radiation. In contrast, naked-eye comets appear white, a result of sunlight reflecting off particles of dust and debris.
    Technically titled C/2014 Q2, the comet is named after amateur astronomer Terry Lovejoy, of Australia, who discovered it last August. Lovejoy has identified four earlier comets.
    Night by night, Comet Lovejoy is inching north, from the feet of Andromeda toward the outstretched arm of Perseus. By this time next month it will be one, if not two, magnitudes dimmer and much harder to find as it heads to the outer solar system.
    Closer to home, Venus and Mars hover above the west-southwest horizon at twilight on their way to a fabulous conjunction later this month. They are maybe a half-dozen degrees apart this weekend, the size of your fist held at arm’s length. And Jupiter shines from sunset to sunrise.

Can you spot the naked-eye five?

As the sun sets, look to the southwest for Venus. With a clear view of the horizon, you might spy Mercury below and to the right of Venus at week’s end, but the innermost planet’s viewing days are numbered. Roughly 15 degrees above Venus, look for the ruddy glow of Mars.
    Thursday and Friday evening the thin crescent moon joins the throng, somewhat between Venus and Mars the first night and above Mars, forming a horizontal line with Venus the next. Venus sets within an hour of the sun, while Mars sets around 8pm. But night by night, Venus is gaining about a minute of visibility, closing the gap with Mars in the process and leading to a conjunction of the two later next month.
    As these twilight planets set in the west, another rises in the east. Jupiter is hard to miss, as it is the brightest object in that part of the sky. By 9pm it is high in the east, at midnight is near the celestial zenith, and as dawn nears it is ablaze above the west horizon. A dozen degrees below the giant planet is fainter Regulus, which marks the dot of what looks like a backwards question mark. This asterism is called the Sickle of Leo and makes up the head of the larger constellation Leo the lion. A triangle of stars to the left of the sickle marks the lion’s haunches, the brightest being Denebola, which in Arabic means the lion’s tail.
    Saturn rises in the wee hours of the morning, and by 6am it is well-placed in the southeast. Its rings are tilted our way so that they stand out against the planet’s surface when viewed with even a small telescope. Saturn sits at the head of the constellation Scorpius, with its red heart Antares 10 degrees below the planet and the creature’s body trailing away toward the horizon.
    The moon waxes to first-quarter phase Monday, when it is almost directly overhead at sunset. Wednesday after sunset it is just a few degrees above and to the left of Aldebaran, the glaring eye of Taurus the bull, and the Hyades star cluster. Higher still are the stars of the Pleiades cluster, the Seven Sisters. While the moon’s light may make both clusters appear as fuzzy spots, simple binoculars will reveal many distinct stars in each.

Even invisible, it tugs our tides mightily

Look for the waning crescent moon in the southeast before dawn Friday. Golden Saturn is just a couple degrees above, while fiery Antares is less than 10 degrees below. The trio rises around 4am, and by 6am they are well placed above the southeast horizon.
    Tuesday marks new moon — the first of January’s two Supermoons. What? How can new moon be a Supermoon? The criteria for the relatively new term Supermoon isn’t that we can see it, but rather that the moon, sun and earth are all three aligned in conjunction with the moon’s closest point to earth in its monthly orbit, called perigee. This can happen during both full moon and new moon. There will be six Supermoons in 2015, with January, February and March coinciding with new moon and July, August and September with full moon.
    New or full, a Supermoon can create super tides. The alignment of earth, sun and moon at new and full moon creates a gravitational tug resulting in strong spring tides. High tide is higher than normal, and low tide is lower. A Supermoon’s closer proximity to earth adds to the pull, creating even greater swings in what are called perigean spring tides.
    Look for the nascent crescent moon to reappear low in the west just after sunset Wednesday, with Venus just a few degrees to the moon’s left and Mercury between the moon and the horizon.
    Mercury and Venus were one degree apart last week, but now the innermost planet is sinking back toward the western horizon and the glare of the sun. They are still within three degrees of one another Friday, but by Wednesday the gap will have grown to almost 10 degrees.
    Mars is above and to the left of Venus and Mercury at sunset, visible until 8pm. Monday the red planet appears within 15 arc minutes — one-quarter degree — of distant Neptune in a rare planetary conjunction. At magnitude 8, Neptune demands binoculars or better yet a telescope. Start at Mars and scan above and to the left.
    Keep the binoculars handy, and look for Comet Lovejoy Saturday eight degrees west-southwest of the Pleiades star cluster, high overhead above Taurus the bull after dark.

The sky is awash in the sun’s absence

While winter has only just begun, it’s heartening to know that a little more sunshine is creeping into our lives day by day. Since a month ago, we’ve gained 15 minutes of light at day’s end, with sunset now after 5pm. Monday marked the latest sunrise of the year, at 7:25, and although it’s a slow go at first, that time will inch earlier hereafter. Heck, before you know it will be summer.
    The winter moon wanes through morning skies, reaching last quarter before dawn Tuesday, when it hovers less than two degrees north of the blue-white star Spica. Look for the two high in the south around 6am that morning. Look to the southeast for early-rising Saturn, which is roughly a dozen degrees above the red-giant Antares.
    Jupiter rises around 8pm, but it is high over the west horizon in the hour before sunrise. Look to its left for the backwards question mark known as the Sickle of Leo, punctuated by brilliant Regulus at its base.
    The real show-stoppers are Mercury and Venus, which will be within one degree of each other low in the southwest shortly after sunset most of the week. The two planets are at their closest Saturday, a mere 0.7 degrees apart. You should have no trouble spotting Venus, which outshines everything else visible and is more than a dozen times brighter than its neighbor. Even so, Mercury is one of the brighter objects in the heavens shining at magnitude –0.8. Look for them above the southwest horizon about 45 minutes after sundown.
    Mars, too, joins the fray, well to the upper left of Mercury and Venus. The red planet is no match for either of its kin, but its ruddy tint easily sets it apart from the similarly bright stars around it. Mars sets around 8pm.
    As darkness settles, the unmistakable hourglass figure of Orion the hunter appears above the southeast horizon. By 10pm, he stands high in the south, facing his quarry the bull Taurus to the west. Orion boasts two of the 10 brightest stars: Fiery Betelgeuse marks the shoulder of the hunter’s upraised arm, while icy Rigel marks his opposite foot.
    Perhaps most noticeable, however, are Orion’s three tightly aligned belt stars. Follow these stars toward the horizon and they point to the brightest star of all, Sirius in the constellation Canis Major, the Great Dog. Another grouping of stars hangs from Orion’s belt, marking the hunter’s sword. One of these, appearing as a fuzzy patch of light, is no star at all but rather a stellar nursery, the Orion Nebula.

The Geminid meteors are unique

This week’s celestial highlight is the annual Geminid meteor shower, which peaks late Saturday and before sunrise Sunday. This coincides with the rising waning moon, which just shy of last-quarter still shines quite bright. Fortunately, the Geminids are some of the brightest “shooting stars,” and given patience and a dark spot away from urban glare, you could still expect to see one or two meteors each minute. Plus the Geminids generate a fair number of meteors for several days before and after the peak.
    Like all meteor showers, the Geminids occur as earth passes through a trail/stream of cosmic dust and detritus. As these bits of rock and ice hit our atmosphere, they burst into flames. While the end results are the same, the source of the Geminids’ debris trail is unique. In every other case, these trails of debris are left by comets orbiting the earth in the same way as the planets. The source of the Geminids, however, is a five-kilometer asteroid, known as 3200 Phaethon, that passes between the sun and Mercury every 1.4 years.
    And where comets orbit the sun with a long tail releasing a trail of flotsam, 3200 Phaethon has no tail but somehow produces a trail of debris anywhere from five to 500 times larger than any spawned of comets. Instead of a tail of its own releasing fragments as it’s heated by the sun, 3200 Phaethon pulls bits of dust and debris into its wake as it travels the solar system in a way astronomers are still trying to explain.
    Many meteor showers have been seen since the dawn of civilization, but not the Geminids. They were first noted in 1862 — simultaneously — by an American and a British astronomer, who each recorded an average of 14 meteors an hour. Year by year, that number grew, even as astronomers searched for the shower’s source. Then in 1983, armed with the Infrared Astronomical Satellite, they found 3200 Phaethon to be the parent of the Geminids. By that time, the shower had grown to an average of 120 meteors an hour under good conditions!
    With clear skies you can see the spawn of 3200 Phaethon anywhere in the dark sky, but all point back to the constellation Gemini.
    While you’re at it, look for Jupiter rising in the east-northeast around 10pm and high in the south come dawn. Saturn rises just ahead of the sun in the east-southeast. And Venus and Mars are both visible after sunset.

When there aren’t 24 hours in a day

The full moon rises at sunset Friday and sets at daybreak Saturday morning. Look for it less than about two degrees from Aldebaran, the heart of Taurus the bull. December’s full moon is known as the Cold Moon, the Long Night Moon and the Moon Before Yule. And as we approach winter solstice, these are the longest nights of the year.
    In fact, Sunday marks a turning point in the tug between light and dark, with the earliest sunset of the year at 4:45. Why, you may ask, is the earliest sunset separated from the shortest day of the year by two weeks? Two factors come into play, one celestial the other of our own contrivance.
    Earth’s elliptical orbit around the sun creates a skew in the exact point of solstice — the overall shortest day — and the earliest sunset and the latest sunrise, which won’t occur until January 4 for us along Chesapeake Bay.
    Additionally, modern timekeeping bases each day on a 24-hour cycle. However, the time between one sunrise and the next — or one sunset and the next or high noon from day to day — seldom adds up to an even 24 hours. The cycle of a solar day is dictated by the time it takes for the earth to make one full rotation. And the speed of earth’s rotation changes, spinning faster when closer to the sun, as it is this time of year, and spinning slightly slower when it is farther away in June, July and August.
    So while the time of sunset will hold for the next week or so, we will continue to lose another six minutes of sunlight in the early mornings before reaching solstice December 21 and more still until January 4.
    Venus is slowly pulling away from the sun, appearing for a few minutes in our early evening sky before disappearing below the southwest horizon. At week’s end this evening star sets roughly 40 minutes after the sun, but each night she appears a little higher and remains visible more than a minute longer than the night before. Even so, you may need to scour the horizon with binoculars to see this planet so early in its evening apparition.
    Mars, too, comes into view as the sun sets, quite a bit higher than Venus but also dimmer. Shining at first-magnitude, the red planet is as bright as the average star — enough to be seen during full moon. While pulling away from earth, it nonetheless maintains its brightness through December and remains in view until setting around 8pm.
    Around 10pm, Jupiter rises in the east-northeast, the brightest object at that time other than the moon. By dawn it is high in the south, with the much fainter blue-white star Regulus 10 degrees to its lower left. The night of the 10th, Jupiter trails the waning gibbous moon by about the same distance. The two travel together throughout the dark hours, shining high in the southwest as dawn approaches.
    If you’re up in the hour before dawn, you may be able to spot the return of Saturn. It is quite low in the east-southeast as the sky begins to lighten, another target perhaps requiring binoculars to see amid the growing glare. But each morning it creeps a little higher and by month’s end is visible a full hour before sunrise.

Constellation joins moon and Jupiter, hosts meteors

As twilight gives way to darkness, look for Mars low in the south-southwest. At first magnitude, the red planet is no brighter than your average star, so scouring the horizon with binoculars may help you find it. Can you make out the teapot shape of Sagittarius below? Mars is just above the handle, while the spout points toward the now-set sun.
    Jupiter rises in the east-southeast a little before midnight, and by 6am it is almost directly overhead. Early Friday morning it is less than 10 degrees above the last-quarter moon. Saturday the moon is just below Aldebaran, the heart of Leo the lion. Sunday Jupiter, Regulus and the moon form a near-straight line, each roughly 10 degrees apart.
    The following nights, the moon shifts eastward compared to Jupiter and Regulus, until Wednesday a thin crescent rises before dawn with blue-white Spica just three degrees away.
    The waning moon shouldn’t interfere with the peak of this year’s Leonid meteor shower in the wee hours Tuesday morning. With clear, dark skies you may see 15 to 20 meteors in a given hour. The meteors can appear anywhere in the sky, but traced back they appear to emanate from the shower’s namesake, Leo.