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ATLANTIC SKIES: Spring arrives, along with a ‘supermoon’

GOES satellite captures spring equinox (Note: the sun in this image is artificially created, though the GOES spacecraft does have sensors continually monitoring the sun for solar activity.)
GOES satellite captures spring equinox (Note: the sun in this image is artificially created, though the GOES spacecraft does have sensors continually monitoring the sun for solar activity.) - Photo courtesy of NASA

Also, watch for the zodiacal light above the western horizon for the next two weeks

Glenn Roberts
Glenn Roberts

Today marks the vernal equinox, the start to the spring season here in the northern hemisphere, officially commencing at 6:58 p.m. ADT/6:28 p.m. NDT this evening.

Already the weather is beginning to mellow (at least somewhat here in Atlantic Canada) with warmer daytime temperatures and not quite so cold nights. At the time of an equinox, day and night are approximately the same length of time (depending on exactly where you live in the northern hemisphere). From this point forward, the length of the daylight period will slowly increase until we reach the summer solstice (the official start of summer) in June.

Mars (mag. +1.4) still rules the early evening sky through the latter part of the month and into early April. Look for the red planet in the constellation of Taurus - the Bull about halfway up the SW sky about an hour after sunset. It drops below the horizon about 4 hours after sunset. Mars sits below the Pleiades ("The Seven Sisters" star cluster) in the western sky around 9 p.m. on March 22 and to the left of the cluster (beautiful in binoculars) on March 30.

A few hours after Mars has set, Jupiter and Saturn make their entrance onto the celestial stage. First up is Jupiter (mag. -2.2), rising in the constellation of Ophiuchus - the Serpent-Bearer around 1 a.m. by month's end, followed by Saturn (mag. +0.6) in Sagittarius - the Archer around 3 a.m. The waning, crescent moon sits next to Saturn on the morning of March 29. Jupiter and Saturn are joined by Venus (mag. -3.9) in the constellation of Aquarius - the Water-Bearer in the pre-dawn sky. On April 2, look for the very thin, crescent moon just below Venus as the eastern sky begins to brighten.

Mercury follows Venus above the ESE horizon about 1 hour before sunrise. Due to its dimness (mag. +0.8), and its low altitude (about 5 degrees above the horizon), you will need an unobstructed view of the horizon and a pair of binoculars to spot our solar system’s smallest planet. An interesting note: astronomers have recently confirmed that Mercury, not Venus, is actually the closest planet to Earth, most of the time.

The zodiacal kight, a hazy, pyramid-shaped cone of light extending above the western horizon (tilted slightly to the left) after the sun has set and the sky darkens, will, when weather permits, be visible for about the next two weeks. The zodiacal light is sunlight reflecting off a myriad number of comet and asteroid dust particles occupying the inner part of our solar system. It can be difficult to see except under a very clear evening sky from a dark site; nonetheless, it is a beautiful sight under the right conditions.

The full moon tonight is the third of three “supermoons” in a row for 2019 (the first was Jan. 21, the second, Feb. 19). A “supermoon” is defined as a full or new moon that comes within 90 per cent of its closest (perigee) approach to Earth, which is approximately 361,740 kms or less, measured from the centre of Earth to the center of the moon. Tonight’s full moon will come to within approximately 360,772 kms of Earth, appearing only marginally brighter and bigger than normal.

Incidentally, the moon reaches its full phase fewer than four hours after the Vernal Equinox.

Until next time, clear skies.
 

Events:

  • March 20 - Vernal equinox; 6:58 p.m. ADT/6:28 p.m. NDT
  • March 20 - Full "supermoon"; 10:43 p.m. ADT/10:13 p.m. NDT
  • March 22 - Zodiacal light; western sky after sunset; next two weeks
  • March 28 - Last quarter moon
  • April 1 - Moon at apogee (furthest from Earth)
  • April 2 - Very thin, crescent moon below Venus; dawn sky


Glenn K. Roberts, who lives in Stratford, P.E.I., has been an avid amateur astronomer since he was a small child. His column runs every two weeks. He welcomes comments from readers at glennkroberts@gmail.com.

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