and Sunset Times for
The Summer Solstice occurs in Moab on June 20. At 11:45pm the sun’s apparent path across the sky reverses its northward trend and begins to drift southward again.
Notice that the time of sunrise varies by only four minutes during June. As the earth swings around the far end of its elliptical path about the sun, its northward movement becomes minimal. The earth’s primary direction of movement at this time parallels the east-west movement of the sun across the sky. Before the solstice, the time of sunrise occurs a few seconds later than it would in a perfectly circular orbit. For a few days after the solstice, sunrise occurs a few seconds earlier than it would in a circular orbit. Once the earth is back on its more linear trajectory, it speeds up and this effect disappears. There is a similar stalling of the times of sunset, but its effect is more apparent after the solstice.
Another effect of the summer solstice is an extension of twilight to nearly two hours before sunrise and two hours after sunset. The northern hemisphere reaches its maximum tilt towards the sun at this time. As a result, the more northern latitudes receive longer periods of daylight as the circumference of the earth decreases towareds the North Pole. Civil twilight is the period of strong natural light for about 30 minutes before sunrise and after sunset. Nautical twilight continues another 30 minutes. The appearance of color in the morning landscape and its disappearance after sunset is one of the key features of nautical twilight. Throughout most of the year, the transition from morning darkness or the transition to a dark night sky takes another 30 minutes. It is this period of astronomical twilight that doubles from a half hour to an hour near the solstice.
June evenings begin with a waxing moon high in the southern sky. Full Moon occurs June 7 at 12:12pm. The moon rises that evening at 9:08pm. By June 11, it will not rise until after midnight. The last quarter moon occurs on June 15. New Moon arrives at 1:35pm on June 22. The first quarter moon occurs on June 29. A waxing crescent moon returns to the western sky after twilight during the last week of the month. Look for a waning gibbous moon near Jupiter in the early morning twilight of June 13. Before sunrise on June 19 look toward the eastern horizon for a crescent moon with Mars and Venus trailing close behind. The moon appears below Saturn on the evening of June 27 and below Spica (Virgo) on June 30.
Arcturus (Bootes) is the 0-magnitude star overhead in the evening sky. Look a bit southwest for magnitude +1 star, Spica, in the center of Virgo. Leo, the lion, dominates the western sky. Magnitude +1 star, Regulus, marks the front flank of Leo and Saturn marks its rear flank. The bright constellations of the eastern sky highlight the path of the Milky Way trailing north to south across the sky. Deneb, a magnitude +1 star, marks the tail of Cygnus, also known as the Northern Cross. The small constellation west of Cygnus is Lyra, the harp. It features 0-magnitude star Vega. The first magnitude star southeast of Cygnus and Lyra is Altair, marking one shoulder of the eagle. Deneb, Vega, and Altair are the three points of the Summer Triangle. Look for faint Hercules and the Corona Borealis between Lyra and Bootes. Scorpius highlights the southern horizon with Sagittarius trailing behind after midnight.
Jupiter - About one hour after midnight Jupiter appears above the LaSals with the constellation Capricornus. By morning it is high in
the southern sky. (Magnitude -2.4)
Mars - Find Mars rising just below Venus around 4:00am each morning. On June 11 the two planets rise at the same time, both in
Aries. By the end of June, Mars rises almost 20 minutes ahead of Venus. (Magnitude +1.1)
Saturn - Look for Saturn high in the western sky at Leo’s hind flank. First magnitude star, Regulus, marks the front flank.
Venus - Find Venus in the eastern sky each morning soon after 4:00am. On June 5 Venus reaches its greatest angular distance from
the sun. That is the point in its orbit that is at a right angle to a line drawn from Earth to the sun. Since Venus is an interior
planet, it passes through phases just like our moon. Fifty percent of the planet’s face toward us will be lit on June 5. As Venus
continues its orbit towards the far side of the sun, it diminishes slightly in magnitude even though its lighted surface is waxing
to 60 percent coverage by month’s end. (Magnitude -4.2 to-4.0)
Note: Apparent magnitude values range from -4 to +6 for most planets and visible stars. The lower the value the brighter the object. A decrease of 1.0 magnitude is 2.5 times brighter.
Note: Hold your hand at arm’s length to measure apparent distances in the sky. Adjust for the size of your hand. The width of the little finger approximates 1.5 degrees. Middle, ring, and little finger touching represent about 5 degrees. The width of a fist is about 10 degrees. The hand stretched from thumb to little finger equals 20 degrees. The diameter of both the full moon and the sun spans only 0.5 degree.
Primary Sources: USGS, U.S. Naval Observatory,
Trace the Milky Way from north to south in the eastern sky through the constellations Cassiopeia, Cepheus, Cygnus, Aquila, Sagittarius, and Scorpius. The center of our galaxy lies in the eastern region of Sagittarius.
CONSTELLATIONS this MONTH
Hold the star chart high above
your head and match the compass directions to the direction
you are facing.
Adjust the star chart by orienting Ursa Major (Big Dipper) to match its position
in the sky.
The star chart approximates the
night sky from astronomical twilight to midnight. As the night
and the month progress, the constellations will shift toward