This is the hottest and most humid month of the year in Maryland. Don’t be discouraged though. There will be that occasional night when the hot weather breaks, and getting reacquainted with the night sky will be an exhilarating experience. So keep your eye on the weather and take advantage of those wonderful nights. Be sure to look for the Summer Triangle, which a large triangle of bright stars that is nearly directly overhead at nightfall. These stars are Vega in the constellation Lyra, Altair in the constellation Aquila, and Deneb in the constellation Cygnus.
The sky map below represents the sky as it will appear in mid-August at the end of astronomical twilight, or the arrival of complete darkness, at about 9:30pm EDT. The Scope Out monthly focus is on the constellations that are just to either side of the meridian, which is near the 18th hour (18h) of right ascension line in the August sky map below. For a primer on how to use this sky map, please read How to begin Observing the Night Sky.
Scope Out divides the celestial sphere into three zones to aid in finding constellations:
3. Southern Constellations: The best-placed constellations in April are Ophiuchus, Serpens, Scorpius and Sagittarius. Some of these, Scorpius and Sagittarius, for example, never rise very far above the horizon because of their deep southern declination.
Mercury is an evening object most of this month, appearing low on the western horizon as darkness falls. Mercury will be in conjunction with Jupiter on August 6th, and Jupiter, Mercury and the bright star Regulus can be seen within 1° of one another on August 7th. Mercury reaches this apparition’s brightest magnitude (-1) on August 21st, and its greatest eastern elongation on August 31st. Venus can be glimpsed by a determined binocular viewer early in the month. It will be very low on the horizon, and it will set just a few minutes after sunset. By mid-month, Venus will be lost in the sun’s glare, and thus a spectacular evening apparition ends. By month’s end, Venus will be on the other side of the sun as viewed from earth, and can be seen low on the eastern horizon about 30 minutes before sunrise. Jupiter also ends its evening apparition this month as it slips into the sun’s glare early in August, not to be seen again until it reappears as a morning object in September. Mars is a morning object, rising on the eastern horizon just before sunrise. Saturn, the sole bright planet that is easily visible, steals the planetary show this month. Look for it low in the southern sky near the distinct head of Scorpius. Uranus and Neptune are still morning objects that rise above the eastern horizon in the wee hours of the morning They can be seen by a determined binocular observer.
THE LUNAR CALENDAR
Conjunction with Saturn
Very close grouping of Mercury, Jupiter and Regulus – August 7th
These three objects will be positioned within 1° of one another providing a pretty grouping with the unaided eye, or within a telescopic field of view at low magnification.
Perseid Meteor Show – August 11 to 14.
The moon, a waning crescent, is well positioned to provide a dark sky for observing the Perseids this year.
© James R. Johnson, 2015