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The Sky This Week, 2018 May 1 - 8

Another cross-quarter day, and Jupiter dominates the night.
Messier 81 and 82 in Ursa Major
Messier 81 and 82 in Ursa Major, 2016 December 31,
imaged with a 10.2-cm (4-inch) f/6 Explore Scientific AR-102 refractor
and a Canon EOS Rebel T2i DSLR.

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The Moon moves into the morning sky this week, scudding above the southern horizon as she wends her way through the summer constellations and the rising stars of autumn.  Last Quarter occurs on the 7th at 10:09 pm Eastern Daylight Time.  Luna may be found in the vicinity of Saturn on the mornings of the 4th and 5th.  Look for ruddy Mars just two degrees south of the Moon before dawn on the morning of the 6th. 

May 1st is one of the four “cross-quarter” days that appear in traditional seasonal calendars.  Many of us are aware of two others, which are widely observed in the U.S. as Halloween and Groundhog Day.  The cross-quarter days and seasonal astronomical dates of solstices and equinoxes were the anchors of the annual cycle of the seasons and pre-date the establishment of many calendars.  The origins of these celebrations date back over a thousand years and were important dates in many cultures.  Celebrated as Floralia in the days of the Roman Republic, it was observed as Beltaine by European Pagans.  It was “Christianized” by Germanic tribes in the 9th Century as a celebration of the feast day of Saint Walburga, an 8th Century abbess who brought the new religion to Germany.  It is often thought of as the first day of summer, and it is still widely observed with rituals such as crowning May Queens, dancing around May poles, and general merrymaking.  In addition to traditional observations, May Day has in more recent times become synonymous with a holiday for laborers that is widely observed, particularly in countries with Socialist or Communist societies.

As we move into the nights of late astronomical spring we have to wait later and later to enjoy a fully dark night sky.  Astronomical evening twilight now ends shortly before 10:00 pm EDT, and by this time bright stars of the winter constellations are dipping below the western horizon.  At this time you’ll find one of the springtime’s most familiar star patterns nearly directly overhead.  The “Big Dipper” asterism is one of the most familiar patterns in the sky, even though none of its seven stars are brighter than second-magnitude.  The Dipper is a small part of the sprawling constellation of Ursa Major, the Great Bear.  If you ignore the bear’s preposterously long “tail” made by the “handle” of the Dipper, you can almost make out a respectable Bear when viewing the sky from a dark-sky site.  This is one of my favorite areas to peruse with my large Dobsonian telescope.  The space between the stars is full of faint smudges of light, the signatures of dozens of distant galaxies set at fantastically remote distances.  

Venus continues to climb higher in the western sky as evening twilight fades to darkness.  The dazzling planet sets over half an hour after the end of twilight, so you’ll have plenty of time to find her cheery glow as she drifts through the setting stars of Taurus, The Bull.

Jupiter reaches opposition from the Sun on May 8th at 9:00 pm EDT.  At this time the giant planet lies exactly opposite the Sun in the sky, rising at sunset and setting at sunrise the next morning.  This is also the time when Old Jove is as close to us as he’ll get this year.  “Close” is a relative term, though; light from Jupiter’s cloud tops takes just over 36 minutes to reach us!

Saturn gets a visit from the waning gibbous Moon on the mornings of the 4th and 5th.  The best time to view the ringed planet is still before sunrise, when you’ll find him crossing the meridian as the sky slowly brightens.  His rings are tipped close to their maximum to our line of sight, and should be easy to spot in just about any telescope.

Mars continues to pull eastward away from Saturn, but his pace is beginning to slow as he approaches the first stationary point in this year’s opposition.  His disc is also steadily growing, and owners of modest telescopes should be able to glimpse details on his dusty face on mornings with steady air.  As with Saturn, your best view of him will be before sunrise.

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