July 2023 - Vol. 27, No. 7

This Month's Night Sky - NOTE: The next paragraph describes the sky as it appears at 10 pm EST (11 pm EDT) near mid- month. The sky also looks this way at 11 pm EST (midnight EDT) during the beginning of the month and at 9 pm EST (10 pm EDT) by month's end.

Bright blue-white Vega (Lyra) shines high overhead as it "leads" the Summer Triangle across the night sky. The "Triangle" is the summer’s most prominent asterism and is made up of three stars: Vega, the brightest, Deneb (Cygnus) and Altair (Aquila). In the SW, Arcturus (Bootes) is dropping towards the horizon as Spica (Virgo) vanishes from sight below. Also look for Antares (Scorpius) low in the SW. The stars of constellations Scorpius and Sagittarius, embedded in the "Milky Way" (part of one of the spiral "arms" of our galaxy), are at their best this month. Look for another famous asterism, "the teapot" (Sagittarius). The "Great Square of Pegasus" asterism, now appears on the Eastern horizon just before the onset of morning twilight. These are the stars of autumn that will take over when the northern summer wanes!

MERCURY opens July in superior conjunction will and return to the evening sky favoring southern hemisphere observers. Mercury will buzz past the Beehive star cluster (M44) and make a close pass of Regulus in Leo on the 29th.VENUS still graces the twilight evening sky, reaching -4.7 magnitude as it is overtaking Earth. MARS moves from Cancer into Leo passing within a degree of Regulus on the 10th, fading to 1.8 magnitude by month's end. JUPITER becomes higher in the morning sky this month, rising around 1am by month's end. SATURN in Aquarius, rises around 10:30 pm by month's end. URANUS rises in the morning sky, gaining height as the month progresses. NEPTUNE rises around midnight in Pisces.

Review how to determine Angular Measurement.

Calendar of Events

NOTE: For those observers not in the ET zone, convert the calendar times to your zone's time by subtracting one hour for CT, two for MT and three for PT. Don't forget to adjust for Daylight Savings Time when necessary by subtracting one hour from your planisphere's time. Dawn and dusk times must also be corrected. See your local newspaper, TV news, or cable TV's Weather Channel for sunrise and sunset times or check with the U.S. Naval observatory. Unfortunately some of these events may occur during daylight hours in your area.

DATE	EVENT
01	Mercury at superior conjunction. Alpha Scorpii, Antares, 1.5 deg. S. of Moon. Neptune stationary.
03	July's full moon is often called the "Buck Moon" because it is the time of year that young buck deer begin showing antlers.
04	Moon at perigee.
06	Earth at aphelion, farthest from the Sun in its orbit.
07	Saturn 3.0 deg. N. of Moon. Venus at greatest illuminated extent.
08	Mercury at greatest heliocentric lat. N. Neptune 1.7 deg. N. of Moon.
10	Mars 0.7 deg. N. of Alpha Leonis, Regulus.
11	Jupiter 2 deg. S. of Moon.
12	Uranus 2.0 deg. S. of Moon.
13	Moon 1.7 deg. S. of the Pleiades (M-45).
15	Mercury 0.2 deg. N. of Beehive (M44).
19	Mercury 4.0 deg. S. of Moon.
20	Moon at apogee. Venus stationary
21	Mars 3.0 deg. S. of Moon.
22	Pluto at opposition.
28	Antares, Alpha Scorpii 1.3 deg. S. of Moon.
29	S. Delta Aquariid meteors peak, this shower produces up to 20 meteors at its peak. Mercury 0.1 deg. S. of Alpha Leonis, Regulus.

Lunar Almanac for July 2023

Phases of the Moon	Phase and Date(s)	Best viewed before local midnight
	New 17	Deep Space Objects
	1st. Qtr 25	Planets & Moon
	Full 03	Moon
	Last Qtr 09	Deep Space & Planets

Topic of the month: Ophiuchus, the Serpent Bearer

The Summer sky merits a good long look into Ophiuchus, the constellation of the serpent bearer. It is called this because it splits the constellation of Serpens into two parts. Owing to its lack of bright stars, (none over 2nd magnitude) and its unpronounceable name (O-fee-u-kus), this constellation may remain obscure to casual observers.

Ophiuchus is generally identified with Aesculapius, a mythological doctor. The staff of Aesculapius wrapped with serpents is a well-known medical symbol. A good deal of this constellation is on the ecliptic (more than Scorpius), and its field is resplendent with globular clusters, because it lies near the center of our galaxy.

Two fine globular clusters, visible in the same wide angle field, M-10 and M-12 are beautiful specimens. M-12 is closer, larger and looser than M-10. The other Messier globulars in Ophiuchus include M-14, M-19, M-62 and M-107, but these are not as spectacular as the first two.

Ophiuchus also contains some beautiful star clusters, notably NGC 6633 which contains about 65 stars of 7th magnitude, and IC 4665, a loose cluster of 7th magnitude stars that is quite nice in binoculars or a wide angle telescopic eyepiece.

Nor is Ophiuchus without double stars. Tau Ophiuchi is a close pair of stars, mag 5.3 and 6.0, that require at least 75 mm of aperture to separate. 36 Oph contains two orange dwarf stars shining at 5.3 magnitude. 70 Oph is more well known, once suspected of harboring planets. It is a color contrasting double with orange and yellow components that need 100 mm of aperture, high power and good seeing to separate. William Herschel proved that the two stars were orbiting a common center, providing proof that Newton's law of gravitation worked outside of the solar system

Ophiuchus also contains more than a few planetary nebulae, the best of these is probably NGC 6572, 10th magnitude. Perhaps the most celebrated of all objects in this fascinating constellation is Barnard's Star, the star with the highest proper motion of all known stars. Barnard's star does have at least one planet, it is a red dwarf and at 9.5 magnitude it can't be seen without a telescope.

--See You Under the Stars!
Astra for Astra's Almanac