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Regulars (Sky Watch by J. Alex Knoll)

Our closest approach to the sun does make for the shortest season

Twilight Thursday and Friday evening reveals the new crescent moon low in the southwest with Venus blazing a few degrees away tight against the horizon. Venus sinks lower in the early evening sky over the next week, finally disappearing between the sun and earth on January 11. Then, after a few days absence, it reappears in pre-dawn skies, where it will blaze as the Morning Star until autumn.
    Moonless skies provide a dark backdrop for this year’s Quadrantid meteor shower, which is at its best in the wee hours before dawn Friday and Saturday. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Boötes, but can appear anywhere in the sky. The Quadrantids can produce from 50 to 100 meteors an hour, but timing — or more aptly, luck — is essential, as this shower peaks within just a few hours, and then it’s over.
    You shouldn’t have any trouble spotting Jupiter, which reaches opposition Sunday, when it will shine in our night skies from sunset until sunrise, far brighter than any star. At opposition, the gaseous giant is its closest to earth and farthest from the sun, with earth right between the two.
    Mars rises around midnight and is high in the south as daybreak approaches. Far below the red planet is Saturn, actually a little brighter but harder to see so tight against the horizon.
    Saturday, earth reaches its closest point to the sun for the year — called perihelion. At that point the sun is roughly 3 million miles closer to the sun than it is at aphelion in July. While 3 million miles may seem like a lot, the distance has little correlation with the change of seasons, which are a result of earth’s 231⁄2-degree tilted axis. It does, however, affect the length of the seasons, since when the earth is nearest the sun it is also traveling its fastest — more than three percent faster than at aphelion. As a result, the seasons come and go quicker this time of year, with the time between December’s solstice and March’s equinox almost five days shorter than from June’s solstice until September’s equinox. As a result, winter is the shortest season for those of us in the Northern Hemisphere.
    Saturday, two weeks after solstice, is the latest sunrise of the year. Sunrise comes a few seconds earlier than the day before, and while the change will be subtle at first, by the end of the month the sun will rise more than 10 minutes earlier than it does now.

The interloper visits Spica and Mercury

Mercury is putting on its best pre-dawn show of 2013, more than doubling in brightness this week, from +1 magnitude to –0.5 (each order of magnitude is exponential, so an increase from +1 to 0 is a doubling). Monday marks the innermost planet’s greatest elongation — its farthest point away from the sun as seen from earth and its highest point above the horizon. Mercury rises a little before 6am and climbs nearly 15 degrees above the southeast horizon before the sun rises more than an hour later. Ten degrees above Mercury is blue-white Spica, but even this first-magnitude star pales compared to Mercury this week.
    First discovered last September, Comet ISON is heading into the inner solar system for the first time, coming within 700,000 miles of the sun November 27. If the comet survives that close encounter, it could live up to the comet of the century billing. If not, the next two weeks are your best chance to spot this long-distance traveler.
    With binoculars or a small telescope, look for ISON one degree to the west of Spica Sunday before dawn and less than one-half degree to the east of the star the next morning. By next Thursday and Friday, ISON will be within 10 degrees of Mercury — well within your binoculars’ field of view. Perhaps by then it will be bright enough to see with the unaided eye.
    Sunday marks the full moon, the Beaver Moon and the Frost Moon according to lore. The full moon floats just six degrees below the miniature dipper-shape of the Pleiades star cluster, while Monday night it is even closer to Aldebaran, the red eye of Taurus the bull.
    The full moon’s glow washes out all but the brightest meteors in this year’s Leonid shower, which peaks between the 16th and 18th. Still, the Leonids are active through the month, so patience or luck will likely reward you with a few of these shooting stars.

July brings the first of three Super Moons

     As twilight settles to darkness, look to the southwest for ruddy Mars beside the ice-blue of Spica until they set around midnight. Mars is the brighter of the two. They will be their closest Sunday, with less than 1.5 degrees separating them. After that, Mars keeps on trucking, setting course for a conjunction with Saturn on August 4.
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Will the Boötids show or no?

Friday’s new moon provides a dark backdrop for the annual Boötid meteor shower, which peaks after sunset that night and before dawn Saturday. Most years the Boötids are a modest shower, topping out at a dozen meteors an hour. But every now and then, it storms.
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It’s a matter of angles

June’s full Honey, Mead or Rose Moon falls around midnight Thursday.
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Libra’s Zubeneschamali is unique

If you’re up before the sun, you can’t miss Venus, which rises in the southeast by 6am. A half-hour later, this Morning Star is ablaze a good 30 degrees above the horizon, brighter than anything but the moon and the coming sun. As the horizon brightens, Venus climbs higher, growing dimmer until blinking out of view by 7:30am. Wednesday morning, January 29, look for Venus just four degrees above a thin, waning crescent moon before dawn.
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The return of Venus and Mercury brings us a chance to see all five naked-eye planets

A day past full, Thursday’s moon rises as the sun sets. The bright light to its upper right is Procyon, of the constellation Canis Minor. Higher still is golden Jupiter, the brightest object in the evening sky aside from the sun and moon. A couple nights later on the 18th, the waning gibbous moon rises a few hours after sunset in the company of Regulus, the heart of Leo the lion....

This time of year a day is 30 seconds longer

Winter officially begins with the solstice Saturday, December 21. At 12:11pm EDT that day, the sun reaches its most southerly declination, standing still above the Tropic of Capricorn. For the roughly 90 percent of the world’s population that lives in the Northern Hemisphere, this is the first day of winter, the day of the longest night and the shortest day of the year.
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Can the Geminids outshine December’s full moon?

The moon lights up the night this week, starting as a waxing gibbous, reaching full moon Tuesday and waxing slowly through the middle of the week. Look for the near-full moon beside the Pleiades star cluster Saturday.
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While never the comet of the century, it piqued our curiosity

It’s official: comet ISON is no more. NASA confirmed Tuesday that after its first-ever venture from the outer limits of the solar system to the sun, the comet did not survive the onslaught of solar radiation. Born 4.5 billion years ago during the formation of the solar system, ISON had resided in the so-called Oort Cloud a full light-year away. Roughly a million years ago, perhaps after a cometary collision, ISON began its journey toward the sun....