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EI2GYB > ASTRO 16.08.23 10:04l 186 Lines 8365 Bytes #999 (0) @ WW
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Subj: This Week's Sky at a Glance, August 11 - 20
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This Week's Sky at a Glance, August 11 - 20
By: Alan MacRobert August 11, 2023
FRIDAY, AUGUST 11
Ý Mercury and fainter Mars, low in the west in bright twilight, remain less
than 5ø apart through August 16th. But they're getting harder to spot through
the sunset afterglow even with optical aid.
Ý After dark August is prime Milky Way time, and there's no Moon now. The Milky
Way runs from Sagittarius in the south after dark, up and left across Aquila
and through the big Summer Triangle very high in the east, and on down through
Cassiopeia to Perseus rising low in the north-northeast.
Ý Whenever Vega crosses nearest your zenith, as it does fairly soon after dark
now, you know that the Sagittarius Teapot is also at its highest, due south.
Two hours later Deneb passes the zenith. That means it's the turn of
boat-shaped Capricornus, and little Delphinus very high above it, to stand at
their highest due south.
SATURDAY, AUGUST 12
Ý The Perseid meteor shower should be at its peak late tonight, and the sky is
moonlessly dark. In early evening the meteors will be few, but those that do
appear will be long, lovely Earth-grazers skimming far across the top of the
atmosphere. As the hours pass and the shower's radiant point (in northern
Perseus near Cassiopeia) rises higher in the northeast, the meteors will become
shorter and more numerous - the most so from midnight to dawn.
Layer up warmly even if the day was hot; remember about radiational cooling
into a clear sky! A sleeping bag makes good mosquito armor, and use DEET on the
parts of you that remain exposed.
Bring a reclining lawn chair to a dark, open spot where no local lights get in
your eyes. Lie back and gaze up into the stars. Be patient. As your eyes adapt
to the dark, you may see a meteor every minute or so on average when night
grows late. Under light pollution you'll see fewer, but the brightest ones will
still shine through.
The best direction to look is wherever your sky is darkest, usually overhead.
The shower's radiant is the meteors' perspective point of origin if you could
see them coming from the far distance. But you only see them in their last
second or two at they hit the upper atmosphere, and that can happen anywhere in
your sky.
SUNDAY, AUGUST 13
Ý The brightest star high in the southeast these evenings is Altair, with
little orange Tarazed above it by a finger-with at arm's length.
A little more than a fist-width to Altair's left is delicate Delphinus, the
Dolphin, leaping left.
Above Altair, slightly less far, is smaller, fainter Sagitta, the Arrow. It too
is pointing leftward.
MONDAY, AUGUST 14
A winter preview: Step out before the first light of dawn this week, and the
sky displays the same starry panorama it does after dusk around Christmas.
Orion is striding up in the southeast, with Aldebaran and then the Pleiades
high above it. His Belt is vertical. The Gemini twins lie on their sides well
to the left of Orion. Jupiter is very high in the southeast. Capella is very
high in the northeast.
TUESDAY, AUGUST 15
Ý As summer progresses, the Big Dipper scoops down in the northwest during
evening as if to pick up the water that it will dump from high overhead early
next spring.
Ý Also as summer progresses, bright Arcturus moves down the western side of the
evening sky left of the Dipper. Arcturus forms the bottom point of the Kite of
Boötes. The Kite, rather narrow, extends upper right from it by 23ø, about two
fists at arm's length.
The top of the kite is bent slightly down. The kite's short tail flutters down
from Arcturus.
WEDNESDAY, AUGUST 16
Ý As August proceeds and nights begin to turn chilly, the Great Square of
Pegasus looms up in the east, balancing on one corner. Its stars are only 2nd
and 3rd magnitude, and your fist at arm's length fits inside it.
From the Square's left corner extends the main line of the constellation
Andromeda: three stars (including the corner) running lower leftward, about as
bright as those forming the Square.
This whole giant pattern was named "the Andromegasus Dipper" by the late Sky &
Telescope columnist George Lovi. It's shaped sort of like a giant Little Dipper
with an extra-big bowl, and it's currently lifting its contents upward.
THURSDAY, AUGUST 17
Ý The actual Little Dipper, meanwhile, is tipping over leftward in the north.
It's less than half as long as the Andromegasus Dipper, and most of it is much
fainter. As always, you'll find that it's oriented more than 90ø
counterclockwise compared to Andromegasus. It's dumping its contents out.
FRIDAY, AUGUST 18
Ý Twilight challenge. About 30 minutes after sunset, look for the thin crescent
Moon very low due west. Good binoculars or a telescope might be able to show
faint Mars (magnitude +1.8) just below or lower left of it (at dusk in North
America). Below them, Mercury is probably too low and faint now to see at all.
SATURDAY, AUGUST 19
Ý Saturn climbs well up in the southeast by 10 or 11 p.m. Look below Saturn, by
about two fists at arm's length, for Fomalhaut, the Autumn Star already on its
way up. No other 1st-magnitude star is anywhere near there to confuse the issue.
SUNDAY, AUGUST 20
Ý The waning of August means that Scorpius, the proud starring constellation of
the southern sky in July, is tilting over and lying down in the southwest after
dark, preparing to bed down and drift off for the season.
This Week's Planet Roundup
Mercury and Mars are disappearing into the sunset. Both are relatively faint
(magnitudes about +0.5 and +1.8, respectively). Mars is 5ø above Mercury. If
you want to try, use binoculars to scan for them just over the horizon due west
about 30 minutes after sunset. Good luck. Although Mercury is technically
brighter, it will be more dimmed by atmospheric extinction and harder to see
through the sunset aftergl0w lower down. The earlier in the week you try, the
better your chances.
Venus is still out of sight very low in the glow of sunrise.
Jupiter (magnitude -2.5, in Aries) rises around 11 p.m. Watch for it to come up
low in the east-northeast. By the beginning of dawn Jupiter shines very high in
the south.
Saturn (magnitude +0.5, in dim Aquarius) rises in twilight; it's nearing its
August 26th opposition. After dark Saturn glows as the brightest thing low in
the east-southeast. It's highest in the south, and sharpest and steadiest in a
telescope, by about 1 a.m.
Uranus, magnitude 5.7 in Aries, is nice and high in the late-night hours, about
8ø east of Jupiter.
Neptune, magnitude 7.8 at the Aquarius-Pisces border, is high after midnight,
about 2oø east of Saturn.
All descriptions that relate to your horizon - including the words up, down,
right, and left - are written for the world's mid-northern latitudes.
Descriptions and graphics that also depend on longitude (mainly Moon positions)
are for North America.
Eastern Daylight Time (EDT) is Universal Time minus 4 hours. UT is sometimes
called UTC, GMT, or Z time.
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