view counter

Regulars (Sky Watch by J. Alex Knoll)

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.

The lonely star swims with the fishes

Thursday’s full moon is known as the Beaver Moon or the Frosty Moon. It rises around sunset and sets around sunrise. Friday and Saturday the moon is with Taurus, the bull’s red eye Aldebaran high to the left and the Pleiades star cluster higher still. Monday night look for the moon near the Gemini twins Castor and Pollux.
    Mercury is at the tail end of its best pre-dawn appearance of the year. The innermost planet rises in the east-southeast around 5:30 at week’s end and is 10 degrees above the horizon as daybreak approaches. Mercury outshines any nearby stars, but that doesn’t make it easier to spot, but binoculars will help you find it tight against the horizon. Don’t confuse it with Spica a bit higher and to the right or with golden Arcturus much higher and to the left.
    You shouldn’t have any trouble spotting Jupiter before dawn. The gaseous giant rises before midnight and is almost directly overhead before sunrise. The bright star to its lower left is Regulus, the heart of Leo the lion. With Venus hidden behind the sun, only the moon outshines Jupiter in our night skies. You can compare the two between sunset Wednesday and sunrise Thursday the 13th, when the waning gibbous moon is within 10 degrees of Jupiter.
    The only other planet visible is Mars low in the southwest as evening twilight gives way to darkness.
    Early November marks the peak of two meteor showers, the South Taurids November 5-6 and the North Taurids November 11-12. Neither is a prolific shower, and both suffer the moon’s bright glare. But they both have staying power, producing a meteor here, a meteor there for days. Better yet, every now and then these slow movers burst aflame, crossing the sky as fireballs.
    Glance to the south after sunset this time of year and you’re not likely to see much except one bright, blue-white star known as the Lonely One. Fomalhaut appears all the brighter due to the company it keeps. Part of Pisces Austrinus, the Southern Fish, Fomalhaut is the only first-magnitude star amid autumn’s dim, ethereal, water constellations. Only after your eyes have had a chance to adapt to the darkness will you see the creatures within this celestial aquarium: Pisces the fish, Cetus the whale, Aquarius the water carrier, Capricornus the sea goat and Delphinus the dolphin.

Halloween falls right in between

The waxing moon reaches first-quarter Thursday, and as darkness falls on Halloween, it shines high in the south, with the bright star Fomalhaut almost straight below.
    As a holiday, Halloween stretches back thousands of years, but not as a day of costumes and trick-or-treating. It coincides with earth’s path around the sun, falling midway between autumnal equinox and winter solstice.
    The Celts of pre-Christan Britain called this cross-quarter day Samhain, celebrating both the end of the harvest and the end of the year. On this night, the veil between the world of the living and the realm of the dead was thought to be especially thin, so people lit bonfires and lanterns from hollowed-out gourds to ward off spirits.
    As Christianity spread, it merged its own holy days with the pagans’ cross-quarter holidays. Imbolc became Candlemas, now better known as Groundhog Day; Beltane gave way to May Day; Lugnasad became Lammas. And Samhain was absorbed into All Saints Day or Hallowmas, marked on November 1, with the night before Hallow’s Eve.
    Now the cross-quarter day coincides with another ritual, setting our clocks back an hour in the return to Standard Time at 2am the first Sunday of November.
    The first week of November provides the best view of Mercury before dawn. The innermost planet reaches greatest elongation November 1, its farthest west of the sun and its highest in our sky. An hour before sunrise, look for it not quite 10 degrees above the east-southeast horizon — roughly the size of your fist at arm’s length. At magnitude –0.6, Mercury is brighter than any nearby star (all but Sirius, in fact), but binoculars may help locate it in the glow of twilight. Don’t confuse the bright planet for Arcturus higher in the east-northeast.
    You shouldn’t have any trouble finding Jupiter. The gaseous giant rises around midnight, and as dawn approaches it is high in the southeast, bluish Regulus and the other stars of Leo the lion stretched out below it.
    Mars is the only planet visible in the evening, shining no brighter than your average star but still a distinct orange-red. Look for it low in the southwest as darkness settles, where it will remain the rest of the year.
    Early November marks the peak of the South Taurid meteor shower. The higher the constellation Taurus, the more meteors you’re likely to see, although the waxing moon will limit you. Still, the Taurids can deliver the occasional fireball.

Even eclipsed, this star blinds

If you didn’t already know about the partial solar eclipse just before sunset Thursday, you’re not likely to have solar glasses at the ready. Do not look at the eclipsed sun for even a moment as it can cause lasting eye damage or blindness. But you can still watch safely with little preparation.
    Try projecting the image through binoculars. Cover one lens and aim the other at the sun, pointing the eyepiece toward the floor or a piece of paper until the sun’s orb appears. Bring it into focus, and voila! You may want to use a tripod, and you can use a small telescope in the same fashion.
    Another option for watching the sun is a pinhole projector, a perennial science project requiring only two sheets of white paper and a pin. Poke a clean round hole in a sheet of paper. With your back to the sun, hold the pierced paper between the sun and the second sheet of paper until you see the sun’s inverted image projected onto it. Increasing the distance between the two sheets enlarges the image but decreases its sharpness. Or you can get more elaborate using the same principles with a box large enough to put over your head to create a viewing chamber.
    Here along Chesapeake Bay, the eclipse begins Thursday at 5pm with the sun low in the west. Alas, it will still be in full swing come sunset at 6:17pm.
    The eclipse won’t be your only chance to put a pinhole projector to use. The sun right now is in the midst of a massive solar storm, resulting in sunspots large enough to see with the protected-but-unaided eye.
    Sunspots start as massive magnetic bursts deep within the sun that migrate to its surface. While highly charged, this energy is cooler than the sun itself, thus appearing darker than surrounding areas. Once to the surface, the energy flares into space in what are called Coronal Mass Ejections, which can wreak havoc on satellites and take down sections of the power grid. Already the International Space Station has turned to face away from the sun to limit the damage from this solar storm.
    Out of all this violence comes beauty, too, in the form of the Northern Lights. So keep a lookout, as a solar storm of this magnitude could make them visible this far south. Learn more at SpaceWeather.com.
    The moon returns to view Saturday as a thin crescent very low in the west-southwest. Look to its lower right for Saturn. As the moon waxes into the new week, it shines near the planet Mars.

It’s a crowded solar system

If you’ve been out before dawn you’ve likely seen Jupiter blazing in the east. Early Friday morning, the gaseous giant shines left of the waning crescent moon. The following morning you’ll find it above the moon and forming a loose triangle with the star Regulus, the heart of Leo the lion.
    The only other naked-eye planets visible are Mars and Saturn, low in the western sky in the darkening twilight. Saturn is fast on the heels of the setting sun, while Mars is farther to the east. Don’t confuse Mars for Antares, the red heart of Scorpius and roughly midway between the two planets.
    Mars has a close encounter Sunday, when Comet Siding Spring (C/2013 A1) passes within 82,000 miles of the red planet. For comparison, the moon orbits the earth by almost 240,000 miles, and the closest recorded comet to pass us was in 1770 at 1.4 million miles! While a collision isn’t predicted, the comet’s tail will likely engulf the red planet. Even with binoculars you’ll be hard-pressed to see Comet Siding Spring, but a telescope will reveal it above the red planet.
    We have our own close encounter with a comet — Halley’s Comet, no less — in the form of the annual Orionid meteor shower, which peaks late Tuesday and early Wednesday. The comet hasn’t visited the inner solar system since 1986, but each year at this time earth passes through the trail of debris left behind from its countless orbits around the sun. With the waning crescent moon rising shortly before dawn, you might see from 20 to 25 meteors an hour. They can appear anywhere in the sky, but if you trace back their path they radiate from the constellation Orion.
    The sun and moon have a close encounter of sorts Thursday the 23rd, resulting in a partial solar eclipse in the early evening. Be warned: Gazing upon a solar eclipse can cause blindness, and a partial eclipse is all the more dangerous, so look only with a solar filter.
    Just as it takes a full moon for a lunar eclipse like the one two weeks ago, a solar eclipse coincides with new moon, when it passes between sun and earth, blotting out the sun’s disc — or part of it in the case of this partial eclipse.
    Hereabouts the show begins at 5:52pm, with the greatest point of eclipse coming at 6:08, when one-third of the sun is blocked from view. Alas, the sun sets at 6:17 before the eclipse is over.
    Again, do not attempt to watch the eclipse without protective eyewear; use the coming week to find solar glasses or another proper filter.