To the reader:
The Skywatcher's Diary for August 2005 has been prepared by Robert Victor.
Credit to the author and to Abrams Planetarium,
Department of Physics and Astronomy at
Michigan State University, and mention of
our Sky Calendar,
would be appreciated.
A sample issue of the Sky Calendar is available over the Internet. It can be viewed via the World-Wide Web at
http://www.pa.msu.edu/abrams/SkyCalendar/Index.html
If you would like a printed sample of the August issue, please send a long, self-addressed stamped envelope to:
August Sky Calendar
Abrams Planetarium
Michigan State University
East Lansing, MI 48824
Each month, the Department of Physics and Astronomy at Michigan State University makes the Skywatcher's Diary available over the Internet. It can be accessed at
http://www.pa.msu.edu/abrams/SkyWatchersDiary/Diary.html
Current and back-issues of the Skywatcher's Diary are available in our archives at
http://www.pa.msu.edu/abrams/SkyWatchersDiary/Archives.html
Skywatchers Diary: August 2005
- Here's a quick guide to the bright bodies of the solar system. Within an hour
after sunset, look for Venus very low in the west and Jupiter low in the WSW
(more on these brilliant evening planets tomorrow). Mars rises north of east
after midnight. As morning twilight begins to brighten, Mars is high in SE,
while the young crescent Moon is in ENE. About 1 1/2 hours before sunrise
on Tuesday look for Orion rising in the east and the Gemini Twins, Castor
above Pollux, rising to the crescent moons lower left. Saturn emerges below
Pollux later this week and Mercury appears below Saturn after midmonth.
- Within an hour after sunset, look for Venus low in W and Jupiter in WSW, 30
degrees to the upper left of Venus. These two brilliant evening planets will be
fascinating to track as they move 1 degree closer to each other each evening until
their rendezvous on September 1. About 1 1/4 hours before sunrise on
Wednesday, look for the last easy old crescent Moon low in ENE with Pollux 2
degrees to its upper left and Castor 4 1/2 degrees above and a little left of Pollux.
- Locate the Gemini Twins, Castor above Pollux, low in NE to ENE 1 1/4 hours
before sunrise on Thursday, and keep track of them for the next half hour. About
40 minutes before sunrise, if the sky is very clear, use binoculars to try for Saturn
11 degrees below Pollux, and an exceedingly fine thread of a lunar crescent within
5 degrees left of Saturn. From Michigan its only 17 hours until New Moon. From
New England, which catches its view about an hour earlier, the Moon is 18 hours
before New and slightly easier.
- Today at 6 p.m. EDT, the Moon is 406,632 km (252,669 miles) from Earth, its
greatest distance of this year. New Moon occurs at 11:05 p.m. EDT, so the
Moon can't be seen tonight.
- Only 20 minutes after sunset, Venus is low in W, and the very thin young crescent
Moon may be visible in binoculars very low in WNW, 24 degrees to Venus lower
right. From Michigan, the Moon's age (time elapsed since New, when it passed
the Sun) is about 22 hours. (Folks in the Southwest U.S. will have a much
easier time spotting the Moon because its higher and sets later, in a darker
sky.) As the sky darkens, look for Jupiter 27 degrees upper left of Venus.
- The Moon is much easier to see this evening, but you must look early. Half an hour
after sunset, locate Venus in the west with the young crescent Moon 13 degrees to
its lower right. Jupiter is in WSW 26 degrees upper left of Venus. As the sky
darkens, look for Spica 10 degrees left of Jupiter. By next Wednesday evening the
Moon will pass all three objects.
- About 45 minutes after sunset look low in the west for the nearly 3-day old crescent
Moon, with Venus less than 2 degrees to its upper left. Note Jupiter 25 degrees to
Venus upper left. A crescent Moon will be seen near Venus monthly five more
times during Venus current evening appearance, on Sept. 6, Oct. 6, Nov. 5, Dec. 4
and Jan. 1.
- This evening within an hour after sunset, look for the 4-day old crescent Moon low
just south of west, with Venus 9 degrees to its lower right and Jupiter 15 degrees
upper left. Track the Moon nightly as it passes Jupiter and the bright zodiacal stars
Spica and Antares within the next week.
- Face WSW at dusk to find Jupiter 3 or 4 degrees to the upper left of the crescent
Moon. Look early enough to catch Venus low in W, 20 degrees to Moons lower
right. As sky darkens, look for the blue-white star Spica within 10 degrees left of
Jupiter. (Look for this star again tomorrow!) The reddish star Antares, heart of the
Scorpion, is west of due south and just over 45 degrees east of Spica.
- About 30 to 45 minutes after sunset binoculars show the star Spica just
below the Moon. From Michigan the gap between the star and the Moon's southern
cusp (lower point of the crescent) is only about one-quarter of the Moon's
width. The star becomes visible to the unaided eye as the sky darkens, then
the gap between Moon and star slowly widens until they set over two hours
after sunset. As seen from space just above the Earth's Arctic regions, the
Moon will cover the star. Starting next month the Moon will cover Spica from
someplace on Earth every 27- 28 days until 2007. The first event visible from
the U.S. occurs on December 25, but it happens after sunrise from Michigan.
- Within an hour after sunset, look for the fat crescent Moon in SW, Venus very
low in W, and Jupiter-Spica 9 degrees apart in WSW. Tonight the Moon sets
within three hours after sunset, leaving the sky dark and moonless for the
rest of the night, excellent for viewing the peak of the Perseid meteor shower.
Meteors from this shower enter Earth's atmosphere at a speed of 60 km/sec
(134,000 miles per hour), from a direction near the boundary between the constellations
Perseus and Cassiopeia. Meteors can be seen anywhere is the sky, but if you
extend their paths backward, all the true members of this shower will trace
back to a common "radiant" point below the "W" of Cassiopeia, which climbs
ever higher in the northeastern sky until first light of dawn. An hour before
sunrise, look in ENE for Saturn 12 degrees below Pollux.
- About an hour after the Sun reaches its high point in the south today, watch
for the Moon rising some 30 degrees south of east. About 1 1/2 hours before
sunset, look for the Moon in the south. This evening the Moon passes First
Quarter phase and appears 90 degrees or one-quarter of a circle east of the
Sun. At sunset the Moon's right half is illuminated. An hour later the Moon
is approaching SW and Venus is very low in the W. Find Jupiter 20 degrees
upper left of Venus, Spica 9 degrees left of Jupiter, and Antares 20 degrees
left of the Moon.
- An hour after sunset, the waxing gibbous Moon is in SSW, with reddish Antares,
heart of the Scorpion, 6 or 7 degrees to the Moon's left. One star close to
the Moon's lower right and two stars 3 and 6 degrees to Moon's upper right
mark the head of the Scorpion.
- Tonight as the sky darkens, Antares is 7 degrees to the Moon's right. A
pair of stars of 2nd and 3rd magnitudes, 0.6 degree apart and some 11 degrees
to the Moon's lower left, marks the end of the Scorpion's tail.
- This months southernmost Moon passes directly south about 1 1/2 hours after
sunset. From East Lansing, MI, the Moon is only 18 degrees above the horizon,
nearly 6 degrees lower than the midday Sun of the winter solstice of Dec.
21. Binoculars show, less than one degree to Moon's lower right, a 3rd-magnitude
star, Gamma in Sagittarius, marking the tip of the Archer's arrow and the
tip of the spout of the Teapot. Just over 3 degrees left and 5 or 6 degrees
lower left of that star are the two other stars of the spout which also mark
the middle and lower star of the Archer's bow. The top star of the bow (and
of the Teapot) is 6 degrees upper left of the Moon and 7 degrees upper left
of the tip of the spout. Finally, four stars in a trapezoid some 9 to 13 degrees
east of the Moon mark the handle of the Teapot.
- The Moon is in S to SSE at nightfall. Binoculars show the four stars of the
handle of the Teapot 2 to 7 degrees to the right of the Moon. Beginning about
8 days from now, the Moon will rise after nightfall, allowing a brief period
of dark sky viewing of the Milky Way, whose center lies about 5 degrees upper
right of the Teapot's spout.
- Tonight find Venus very low just south of west at dusk, with Jupiter 15 degrees to its
upper left, and Spica about 8 degrees left of Jupiter. Venus is crossing the celestial
equator and sets nearly due west. Watch Venus set farther S until November 5-6.
- One hour after sunrise these mornings, Mars is high in SSE. Summer has just
begun in Mars' S hemisphere. Through a telescope, the planet's S pole is tipped
15 degrees toward Earth, but the rapidly shrinking S polar cap may be hard
to observe. Although the N pole of Mars is tipped away from Earth, it is surrounded
by a N polar hood of haze which extends well onto the visible face of Mars.
To tell the difference between N and S on Mars, nudge the telescope a little;
if you move the telescope S, the S edge of Mars will be the last to go out
of the field. Low in ENE an hour before sunup for the rest of this week, find
Saturn 13 degrees below Pollux, and Mercury within 6 degrees below Saturn.
- Early this morning, at 2 a.m. EDT, the Moon passed the perigee (closest point
of its orbit), 357,393 km (222,074 miles) from Earth. That makes today's Full
Moon the 2nd closest of the year. Tonight the Moon rises in ESE about 25 minutes
after sunset, as seen from southern Michigan. When the Moon is rising or setting,
regardless of its distance, it always seems much larger than when its overhead,
even though when overhead the Moon is nearly 4000 miles closer. This effect,
occurring only in the mind of the beholder, is called the Moon illusion.
- Tonight within an hour after sunset, look very low south of west to see Venus with
Jupiter 12 degrees to its upper left, and Spica 8 degrees left of Jupiter. The Moon,
just past full, rises 10 degrees south of east just under an hour after sunset. For the
next five nights, from the latitudes of Michigan, Moon rises less than half an hour
later each night.
- Tonight the Moon rises just one degree south of due east about 1 1/4 hours after
sunset, before the sky darkens fully.
- Venus and Jupiter are just 10 degrees apart low in WSW to W within an hour
after sunset. Moonrise tonight occurs about 1 hour 40 minutes after sunset,
some 8 or 9 degrees north of due east. An hour before sunrise on Tuesday,
the Moon is high in SSW, with Mars not yet in S and 23 degrees to Moon's upper
left. Low in ENE find Saturn with Mercury 7 degrees lower left. Tomorrow Mercury
is at greatest elongation 18 degrees from Sun, as far as it gets from the
Sun during the current morning appearance.
- Tonight the sky gets very dark, but only briefly. This allows a fine view
of the Milky Way until the Moon comes up some 18 degrees N of due east just
over two hours after sunset and lights up the whole sky. If you're up for
another hour after moonrise, watch for Mars rising 13 degrees to the Moon's
lower left.
- At the end of twilight, about 1 3/4 hours after sunset, go to a dark place
and look for the Milky Way, appearing as clouds of steam rising up from the
spout of the Teapot of Sagittarius in the south. It continues up through the
Summer Triangle and the Northern Cross nearly overhead, and down through Cassiopeia
and Perseus in the northeast. The patch of the Milky Way just south of the
center star of the Northern Cross is very interesting to observe with binoculars.
Known as the Cygnus Star Cloud, it is part of the spiral arm in which our
Sun is located and can easily be resolved into stars. Compare it to the more
distant Greater Sagittarius Star Cloud (the puff of steam over the spout),
in the spiral arm next inward from our location in the Galaxy. Tonight, the
Moon, two-thirds full, rises in ENE about 2 1/2 hours after sunset. About
another half hour later, Mars rises 4 or 5 degrees to Moon's lower right.
Theyre still only 6 degrees apart as dawn brightens on Thursday, when they're
very high in the southern sky.
- At dusk, notice Jupiter 7 degrees upper left of Venus, and Spica the same
distance left of Jupiter. Tonight, the Moon, just over half full, rises 32
degrees north of east three hours after sunset, some 14 degrees left of Mars
and a little lower. In another hour use binoculars to see the Pleiades star
cluster 2 degrees to the Moon's left. Moon and star cluster appear even closer
together at dawn's first light on Friday. Several times next year, the Moon
will occult or cover some of the stars of this cluster. An hour before sunup
on Friday, Mercury appears low in ENE, 10 degrees lower left of Saturn.
- Nearly an hour after sunset, Venus and Jupiter are just 6 degrees apart very low in
W to WSW, and now can both fit within the field of view of most 7-power binoculars.
Ranking next in brilliance in the early evening sky are the yellow-orange star
Arcturus some 33 degrees above Venus, and blue-white Vega nearly overhead.
- Within an hour after sunset, low in W to WSW, look for Venus with Jupiter 5
degrees upper left, and Spica 7 degrees left of Jupiter.
- Tonight, within an hour after sunset, locate Venus low in W to WSW with Jupiter
4 degrees upper left. Look nightly and catch them at their closest on Thursday,
September 1. Also this week, watch the Moon overtake the Gemini Twins, Saturn,
and Mercury at dawn. Tonight's northernmost Moon rises over 40 degrees north
of east about 5 1/4 hours after sunset and passes within 15 degrees south
of overhead within 3 hours after sunrise on Monday.
- At dusk, look low in W to WSW for Jupiter only 3 degrees upper left of brighter Venus. Can you
still see Spica? Its 6 to 7 degrees left of Jupiter and a bit lower. An hour before sunrise on
Tuesday, look for the Gemini Twins, Castor 4 1/2 degrees above Pollux, just to the left of the
waning crescent Moon well up in the eastern sky. Look also for Mercury low in ENE, 15 degrees
lower left of Saturn.
- At dusk find Venus and Jupiter just 2.2 degrees apart, with brighter Venus
to the lower right. An hour before sunrise on Wednesday, locate the waning
crescent Moon between E and ENE. Look for Saturn about 5 or 6 degrees to Moon's
lower right, Pollux and Castor 9 and 13 degrees above the Moon, and Mercury
some 20 degrees to Moon's lower left.
- In early evening twilight, one day before their closest approach, the brilliant pair of planets
is separated by only 1 1/2 degrees, with brighter Venus almost directly below Jupiter.
Using binoculars if needed, look for the star Spica just over 6 degrees to their left. An hour
before sunrise on Thursday, Moon is low in ENE with Saturn 9 degrees upper right and
Mercury 10 or 11 degrees below. Mars is high in S, and Sirius, the brightest star, twinkles
vigorously low in SE. Which now appears brighter, Mars or Sirius?
Please send any comments, suggestions, or questions to
Thomas G. Ferguson:
fergus52@msu.edu
|