Category: Sky Events

Sky events

Winter Solstice

Winter solstice occurs today at 01:12HST. Today the Sun will occupy the most southerly position in the sky of the year. The term solstice comes from the latin terms Sol (the Sun) and sistere (to stand still). On this day the Sun seems to stand still as it stops moving southwards each day and begins move to the north. This is the first day of winter as marked by many cultures in the northern hemisphere.

2012 Solstices and Equinoxes
  UT HST
Perihelion Jan 5 03:59UT Jan 4 17:59HST
Spring Equinox Mar 20 05:14UT Mar 19 19:14HST
Summer Solstice Jun 20 23:09UT Jun 20 13:09HST
Apehelion Jul 4 23:59UT Jul 4 13:59HST
Fall Equinox Sep 22 14:49UT Sep 22 04:49HST
Winter Solstice Dec 21 11:12UT Dec 21 01:12HST
 
Source: USNO Data Services Website and the NASA Sky Calendar

 

The Moon, Mercury and Venus

Tomorrow morning, December 11th, a nice trio will see three bright objects create a close 6° triangle. Lowest of the three will be Mercury, shining brightly at -0.6 magnitude, at about 18° elevation at sunrise. About 4° above Mercury will be a nice 4% illuminated crescent Moon. Above the Moon will be Venus, shining at -3.9 magnitude it will be very hard to miss. About 16° above the trio you can find Saturn, making three bright planets in the dawn. This conjunction should be worth setting the alarm clock early for.

A Line of Planets in the Dawn

Tomorrow morning, December 10th, you will find a nice lineup of planets in the dawn sky. Mercury, Venus and Saturn will be in a line about 20° long. Adding to the lineup will be a nice crescent Moon, a bit over 10° higher in the sky than Saturn.

The view at 06:00HST will find a 19% illuminated Moon at 38° elevation. Working down the line you will see Saturn at 29° elevation, Venus at 15° elevation and Mercury at 9° elevation. With sunrise not until 06:46HST this will give plenty of time to view, and perhaps photograph, a line of planets in the dawn.

Over the next few days the view will be much the same, with the Moon lower each morning. On December 11th the Moon will sit between Venus and Mercury creating a nice trio.

Geminids

The annual Geminid meteor shower has become one of the most reliable annual meteor showers. Known for bright and slow moving fireballs the Geminids can provide a good reason to spend a few hours outside on a December night. This shower has routinely provided rates above 100 meteors per hours in past years, this year should be no exception.

Leonids in Orion
A pair of Leonid meteors streak through Orion, combination of 10 x 15s frames
First observed over 150 years ago this is a interesting meteor shower. The parent body for the Geminids is not a comet as with most showers, but rather the asteroid 3200 Phaethon. It is somewhat of a mystery how this mostly rocky body gives rise to the debris stream needed to generate a meteor shower. The asteroid does orbit well inside the orbit of Mercury every four years, where intense solar heating may heat trapped ice and liberate loose material from the surface.

Stargazing on Hawai’i

Here on the Big Island the single best place to stargaze is the Mauna Kea VIS. The dark skies are usually free of clouds and are well away from the lights of Hilo and Kona. After dark use for stargazing is not only permitted, but encouraged. It can be cold at 9,200ft, bring warm clothes and blankets

The peak is expected to occur around December 13, 07h to December 14, 04h UT. For viewers here in Hawai’i this occurs on the night of December 12th. The Geminids feature a broad peak, with high rates for nearly 24 hours, thus allowing the all time zones a decent chance to enjoy the show.

There should be no substantial moonlight to drown out this years showing, dark skies to allow even the faintest meteors to be seen. The Moon is a thin waxing crescent, 1% illuminated on the morning of the 13th, essentially new.

The Geminid radiant rises round 8pm, thus meteors should be visible all night long. You can stay up late or set the alarm early, your preference. Southern viewers will have to wait until around midnight for the constellation Gemini to rise, making this a morning shower.

Watching meteors requires no more equipment than your eyes and a dark sky, and can be enjoyable for just about anyone. Well? It is December, you should probably add a warm coat to the equipment list.

Mercury at Maximum Elongation

Today Mercury reaches maximum elongation, the furthest point it will reach from the Sun in the sky and the highest it will be above the sunrise for this morning apparition. The planet is easily visible as a bright, starlike object about 15° above the rising Sun as the twilight begins. Over the next couple weeks Mercury will slide back into the sunrise, heading for superior conjunction on February 16th.

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