Abrams Planetarium
SKYWATCHER'S DIARY: July 1995
To the reader
The Skywatcher's Diary for July 1995 has been prepared
by David Nette and Robert Victor. Sometimes you can see next month's in advance by looking in our archives. Credit to
Abrams Planetarium,
Department of Physics and Astronomy at
Michigan State University
would be appreciated. Our illustrated
Sky Calendar accompanies
the printed version of Skywatcher's Diary as it is sent monthly to
Michigan newspapers, but does not accompany this Internet version.
If you would like a sample copy, send your request with a self-
addressed, stamped envelope to
Sky Calendar
Abrams Planetarium
Michigan State University
East Lansing, MI 48824
This month's
most striking sights include the moon passing near planets and
bright stars, on the evenings of July 1-3, 5, 6, 8, 9, 16, and 31, and
the mornings of July 17, 22, and 23. Morning events are mentioned
in Skywatcher's Diary one day prior to the event.
-
- One hour after sundown the waxing crescent moon is low in the W.
The first-magnitude star Regulus is 8 degrees to moon's upper left.
Reddish Mars lies in WSW, 25 degrees upper left of moon and 19
degrees upper left of Regulus. Look in SW for Spica, 35 degrees
upper left of Mars. Watch Mars creep toward Spica an average of 0.6
degree per day in July. By month's end, Mars will close to within 18
degrees lower right of Spica.
-
- An hour after sunset the moon is low in WSW to W with Regulus 9
degrees to its right. Regulus, the heart of Leo the Lion, marks the end
of the handle of the Sickle whose blade forms the lion's and mane.
First magnitude Mars is 13 degrees upper left of the crescent.
-
- An hour after sunset the crescent moon is in WSW with ruddy Mars
5 degrees to its upper right. Second-magnitude Denebola, the tail of
Leo, shines 12 degrees upper right of Mars.
-
- An hour after the sunset, the moon, approaching First Quarter, is well
up in SW to WSW. Mars is 13 degrees right of the nearly half full
moon. Note Spica about 20 degrees to moon's upper left. Given the
moon travels about 13 degrees eastward against the background
stars daily, can you guess where the moon will appear tomorrow
evening?
-
- An hour after sunset the moon, just past First Quarter, is in the SW.
Can you tell where the Sun is by looking at the moon? Spica is 7
degrees to the moon's left.
-
- The waxing gibbous moon, nearly two-thirds full, is well up in SSW
an hour after sunset. Tonight Spica, the spike of wheat in Virgo's
hand, lies 7 degrees to moon's lower right.
-
- From the eastern U.S. after sunset tonight, the moon's dark side
occults, or covers, the 3rd-magnitude star Zubenelgenubi, or Alpha
Librae. Use a telescope to see the star suddenly disappear at the
invisible dark edge of the moon. Here are times of disappearance for
selected cities: Chicago, 9:13 p.m. CDT; East Lansing, 10:20 p.m.
EDT; Atlanta and Detroit, 10:23 p.m. EDT; Toronto, 10:29 p.m.;
Washington, 10:35 p.m.; Miami and Montreal, 10:38 p.m.; Boston,
10:41 p.m. Alpha's 5th-magnitude companion, 4 arcminutes NW of
the brighter primary, gets covered by the moon a few minutes
earlier.
Tonight and Saturday, if skies are clear, MSU Observatory will be
open from 9 p.m. until 11 p.m. for viewing of the moon, Jupiter, and
other celestial objects, as well as tonight's occultation of Alpha
Librae.
-
- An hour after sundown the moon is in the S. Bright Jupiter is 7
degrees lower left of the moon. Antares, the heart of the scorpion,
shines 6 degrees lower left of Jupiter and about 12 degrees lower left
of the moon. MSU Observatory: See July 7.
-
- Look tonight as the moon forms a pretty triangle with Jupiter and
Antares. At dusk the waxing gibbous moon is in SSE with bright
Jupiter 8 degrees to its right and a little higher. Antares in Scorpius
is 8 degrees lower right of moon and 6 degrees lower left of Jupiter.
-
- An hour after sunset face NW and locate the seven bright stars of the
Big Dipper. Its curved handle leads your eye to two bright stars in
SW. Remember: "Follow the arc to Arcturus, and drive a spike to
Spica."
-
- An hour after sunset, the ecliptic, or approximate plane of the solar
system, is well marked by five bright objects: Regulus low in W; Mars
is WSW; Spica in SW; bright Jupiter in SSE to S; and the moon low in
SE. Look also for Antares, the heart of the Scorpion, 6 degrees lower
left of Jupiter. The Full Moon will set just after sunrise on
Wednesday.
-
- The Hay or Thunder Moon rises in the ESE around sunset, or soon
afterward if you're in southern U.S. An hour later, the moon, just
past full, is very prominent, while Jupiter and Antares have nearly
reached the south.
-
- At dusk first-magnitude Mars is low in the WSW. Spica, the spike of
wheat in the hand of Virgo, shines in SW, 28 degrees upper left of
the red planet. Try to detect daily changes in Mars' position by
following it through binoculars for a few days around July 15 and 27
as it passes near 4th-magnitude stars. On July 15, Mars is midway
between Spica and Regulus, and on August 28 Mars will pass only 2
degrees from Spica.
-
- In a few days, as the moon rises later, it allows an ever longer
moonless "window" of time after nightfall, excellent for viewing the
Milky Way. Next week, use a star map and optical aid to locate deep
sky objects in Scorpius and Sagittarius. For a map, send a long, self-
addressed stamped envelope to July Sky Calendar, Abrams
Planetarium, Michigan State University, E. Lansing, MI 48824.
-
- Three and a half hours after sunset the moon is low in ESE. Note
Saturn 11 degrees to its lower left. If observed with a telescope,
Saturn appears "ringless" until August 11 as we see the rings' dark
underside. Wait until Saturn rises high in the sky for the best
telescopic view. The moon is well up in S at dawn Sunday with
Saturn 10 degrees to its lower left.
-
- The waning gibbous moon is low, just S of E, three and a half hours
after sunset. Note yellowish Saturn 5 degrees to moon's lower right.
An hour before sunup Monday the moon is high in SSE with Saturn 7
degrees to its lower right.
-
- Can you see all three naked-eye planets visible in the current
evening sky? At dusk face south for bright Jupiter with reddish
Antares to its lower left. Throughout July, Jupiter remains 6-7
degrees from Antares. Turn to face the WSW for a glimpse of ruddy
Mars, low in the sky. Look later for first-magnitude Saturn; it rises
just S of E about three hours after sundown.
-
- The moon is at Last Quarter Wednesday morning. Face the rising
Sun, and the half-illuminated moon will be 90 degrees (1/4 turn) to
your right.
-
- An hour after sunset the Summer Triangle is well up in ENE to ESE.
Vega, the brightest, marks the top of the triangle, in the east. Altair
is in ESE, to Vega's lower right. Deneb is in ENE, to Vega's lower left.
Just inside the Triangle, about midway between Vega and Altair, is a
3rd-magnitude star which appears single to the unaided eye. Inspect
it with a telescope however, and you'll see two stars of contrasting
colors, yellow and blue. This double star, Albireo, marks the head of
Cygnus, the Swan. Deneb marks the Swan's tail.
-
- Uranus, magnitude 5.6, is up all night this weekend. Use binoculars
and a finder chart to "starhop" to the planet. For a map, send a long,
self-addressed stamped envelope to July Sky Calendar, Abrams
Planetarium, Michigan State University, E. Lansing, MI 48824.
-
- An hour before sunup Saturday the waning crescent moon is in the E
with Aldebaran, the fiery eye of Taurus the Bull, 8 degrees to moon's
lower left. The Pleiades star cluster lies 7 degrees upper left of the
moon.
-
- An hour before sunup Sunday, a beautiful crescent moon reclines in
E with first-magnitude Aldebaran 4 degrees upper right. The
Pleiades or Seven Sisters glitter 14 degrees above Aldebaran.
Betelgeuse in Orion has just risen 19 degrees below the crescent.
-
- At dawn Monday the waning crescent moon is low in ENE to E. The
stars of Orion the Hunter are rising to lower right of the moon. First
magnitude Betelgeuse, marking Orion's shoulder, is 12 degrees to
moonUs lower right. Rigel, Orion's foot, is 19 degrees to the right of
Betelgeuse and, seen from northern states, a few degrees lower.
Using binoculars, aim midway between Betelgeuse and Rigel for the
vertical line of three stars marking Orion's belt. On each successive
morning, Orion is higher and easier to see.
-
- Look very low in ENE 45 minutes before sunup Tuesday for the last
easy old moon. Betelgeuse in Orion is 14 degrees right of the
crescent, while the Gemini Twins, Pollux and Castor, are almost 20
degrees to the moon's left. Binoculars help pick out the Twins in
bright twilight.
-
- An hour after sunset face NW to locate the seven bright stars of the
Big Dipper. The two stars in the front of the bowl of the Dipper are
called the Pointers, because a line connecting them, extended about
one Big Dipper length upper right, points to the North Star, Polaris.
Will anyone see the oldest moon on Wednesday morning? Using
binoculars half an hour before sunup, look just above the ENE
horizon. The moon with Venus 8 degrees to its lower left will both be
a little higher and easier from southern states.
-
- These mornings, as dawn begins to brighten, Saturn is well up in
south, ideally placed for telescopic observation. Saturn's rings
appear "dark" until the night of August 10-11. Using a telescope, can
you detect the shadow of the rings as a narrow dark line on the face
of the planet?
-
- The New moon occurs at 11:13 a.m. EDT. New Moon marks the start
of the lunar cycle, hence the term "new". Mercury is at superior
conjunction, invisible on the far side of the Sun from Earth. Thus four
objects are now aligned in space. In order, they are Earth, moon, Sun,
and Mercury.
-
- Two hours after sundown, look for the Teapot asterism of eight stars
of the 2nd and 3rd magnitude, low in SSE to S. The top star of the lid
and all three stars of the spout form the bow and arrow of
Sagittarius, the Archer. The center of our Galaxy lies some 30,000
light-years away, within 5 degrees upper right of the tip of the
Teapot's spout. From a dark location, note the "steam" billowing
upward from the Teapot's spout -- the Milky Way!
-
- Look early, half an hour after sunset, for the young moon very low in
the W. Binoculars will aid in the search for the thin crescent. Can you
spot the moon with unaided eye? Regulus, the heart of Leo, is 7
degrees to the moon's upper right. Both will be higher and easier
from southern states.
-
- Half an hour after sunset the moon is very low in the W. As the sky
darkens, look higher in WSW for first-magnitude Mars within 20
degrees upper left of the crescent.
-
- As darkness falls the moon is low in WSW to W. Note reddish Mars 7
degrees upper left. That glow you see on the moon's dark side is
earthshine, or sunlight reflected off the Earth to illuminate the
moon.
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