Astronomy news for the week starting Friday, June 21, 2013.
Summer has arrived. The night of Thursday, June 20, the Sun crossed the
Summer Solstice in classical Gemini 23.4 degrees north of the celestial equator. By the time of
sunrise Friday morning, the season will have commenced, with
the Sun rising and setting as far to the north of east and west as
possible. This special day of Friday the 21st will be the longest
of the year, the nights of the 20th and 21st the shortest. Enjoy
the show, because the Sun is now moving southward toward its next
major crossing at the Autumnal
Equinox in Virgo.
Nevertheless, with the Sun only slowly changing its north-south
position, summer will keep getting warmer until perhaps late
August, when the southerly solar crawl begins to make itself felt
in cooler temperatures.
Number two in the skies, the Moon, begins the week in its fat waxing gibbous phase, which ends at full Moon (the "Rose Moon," "Flower Moon")
the morning of Sunday the 23rd near the time of Moonset in North
America. With the Sun near the Summer Solstice, the full Moon will
be close to the Winter Solstice in
Sagittarius, and will thus be the
most southerly and lowest full Moon of the year. Behaving opposite
to the Sun, it rises in the southeast at sunset and sets in the
southwest at sunrise, giving us the shortest full-Moon viewing time
of the year. The Moon then enters the waning gibbous phase, which will occupy the
remainder of the week. Just an hour before formal full Moon, the
Moon passes perigee, where
it is at its closest point to the Earth, the coincidence resulting
in especially high and low tides at the
coasts.
The western evening sky features Venus
(with
Mercury below and descending out of sight). Though it's near
its latest setting time of the year, Venus is still visible only in
twilight, so remains a difficult catch and requires a clear horizon
to see. Beyond Venus, we have much more visible Saturn. After
twilight ends, look just to the west of the southern portion of the
meridian for the brightest "star."
About a dozen degrees to the west lies slightly fainter Spica in Virgo, toward which
Saturn is sluggishly moving while in
retrograde against the stellar background (the result of the
Earth passing between it and the planet). With Arcturus high to the south, Saturn
and Spica make a giant letter "L." The planet is then with us
until well after midnight, not setting until 2:30 or so AM Daylight
Time. In the dawn sky, neither Mars
nor
Jupiter is readily visible.
"June is busting out all over"... and so are its stars. Once the
Moon has moved out of the way, later at night we get to admire the
southern Zodiac's Sagittarius and Scorpius, which lie in the heart of
the Milky Way. The most prominent
part of Sagittarius is its upside-down Little Milk Dipper, while Scorpius really does look like the
scorpion it was named after.
