To the reader:
The Skywatcher's Diary for May 1999 has been prepared by Robert C. 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.
The current 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 May issue, please send a long,
self-addressed stamped envelope to:
May 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
ftp://www.pa.msu.edu/pub/swd/
Two brilliant evening "stars" in May: Venus, at its
greatest height in west at sunset this month, sets late, over 3 hours after
sunset in all of May. The brilliant planet goes between the horns of Taurus
May 2, then crosses into Gemini on May 8. Venus sets farthest north of west
on May 10, over 3-1/2 hours after sunset from northern U.S. On May 16 &
17, Venus, going east 1.1 degree per day, slips within a degree of 3rd-mag
Epsilon in Gemini. On May 21 & 22, Venus forms a nearly isosceles triangle
with Pollux and Castor, 9 or 8 degrees from each. On May 29, Venus passes
4 degrees lower left of Pollux. Mars at dusk in May ascends through
SE and SSE, starting 8 degrees E of Spica and closing to within 2 degrees
of star. On May 1, Mars is nearest, at a distance of 54 million miles;
not until May-August 2001 will Mars be closer! A spectacular occultation
of Regulus by the half-illuminated Moon will take place on the evening
of May 21.
Morning Planets in May:
Mars sets in WSW, first in twilight, then in predawn. Jupiter
is just emerging N of E on May 1, and is still low in E at month's end.
Saturn emerges by month's end, 16¡ lower left of Jupiter.
Skywatcher's Diary: May 1999
Saturday, May 1
One-and-a-half hours after sunset tonight, the brightest objects
in the sky, in order of brilliance, are: The Moon rising in ESE; Venus in
W to WNW, one-quarter of the way from horizon to overhead; Mars about the
same elevation in SE, some 27 degrees to Moon's upper right; and Sirius,
the brightest nighttime star, twinkling low in WSW. Note the first-magnitude
star Spica 8 degrees upper right of Mars, and the 2nd- mag. star Elnath,
northern horn of Taurus the Bull, 3 deg. upper right of Venus. In coming
days and weeks, watch the planets shift their positions against the stars.
Today Mars is closest, 54 million miles from Earth. Venus will swing only
half as far from us on Aug. 20.
An hour before sunrise on Sunday, the Moon is in SW, with the first-
magnitude star Antares, heart of the Scorpion, about 12 degrees to its lower
left. Mars is low in WSW, nearly 30 deg. to Moon's lower right. Using binoculars
40 minutes before sunrise, viewers in southern states can scan the horizon
5 degrees N of E for Mercury rising 1.7 degrees below Jupiter. Even though
both planets are now on the far side of the Sun, Mercury is departing from
the morning sky, while Jupiter is emerging. These planets' different behavior
arises from differences in the orbital periods of Mercury, Earth, and Jupiter.
Sunday, May 2
Three hours after sunset, the reddish star Antares, "Rival of
Mars," has just risen in SE, within 9 degrees to Moon's lower right.
Mars itself is then well up in SSE, about 40 deg. to Moon's upper right.
Mars is now close to Earth and so appears ten times as bright as Antares.
Keep watch until September, when Mars will be farther away and will pass
within 3 degrees above Antares. Mars will remain visible evenings until
May of 2000.
Moon and Antares keep company for the rest of tonight. By an hour before
sunup on Monday, they're in SSW, with Antares 9 degrees below the Moon.
Monday, May 3
Three hours after sunset, Moon is rising in ESE, 15 degrees lower
left of Antares.
Tuesday, May 4
Two hours before sunup on Wednesday, just east of due south, the
Moon is above the Teapot, formed by 8 stars of 2nd and 3rd magnitude in
the constellation Sagittarius, the Archer. The 3rd-mag. star within 5 degrees
below the Moon is Kaus Borealis, the northern star of the Archer's bow;
it also marks the top of the lid of the Teapot.
Wednesday, May 5
Two hours before sunrise on Thursday, the Moon is in SSE, while Mars
and Spica are within 7 degrees apart low in WSW. The 2nd- magnitude star
8 degrees to Moon's lower right is Nunki, or Sigma in Sagittarius, brightest
star in the handle of the Teapot. Antares is in SSW, about midway between
Moon and Mars, 40 degrees from each.
Thursday, May 6
Looking within an hour after sunset, can you still find Aldebaran,
eye of Taurus? Tonight it's about 20 degrees below Venus. Aldebaran gets
lower daily and soon departs from the evening sky. Owing to the Earth's
orbital revolution around the Sun, Aldebaran will appear on the Sun's far
side on May 31. Other bright stars disappearing into twilight this month
soon after Aldebaran are Betelgeuse, in the west 19 degrees lower left of
Venus tonight, and Sirius, low in WSW 27 degrees lower left of Betelgeuse.
Look nightly 45 minutes to an hour after sunset, and determine the last
date you can see each star.
Friday, May 7
At sunrise on Saturday, the Moon is nearing Last Quarter phase in
SSE. Note the Moon is just over 90 degrees (a quarter circle) west or right
of the rising Sun, and is just over half illuminated.
Saturday, May 8
At sunrise on Sunday, the fat crescent Moon is in SE to SSE. It is
less than 90 degrees from the Sun, and so has passed Last Quarter phase.
Sunday, May 9
An hour after sunset, look for Procyon, the Little Dog star, in WSW
30 degrees left of brilliant Venus. Look also for reddish Betelgeuse, shoulder
of Orion, 26 degrees lower right of Procyon and 19 degrees lower left of
Venus. Sirius, the Dog Star, twinkles furiously very low in WSW, 26 degrees
below and slightly left of Procyon. Sirius, Betelgeuse, and Procyon form
the nearly equilateral Winter Triangle. Of its three stars, only Procyon
remains visible into early June for observers at mid-northern latitudes.
Monday, May 10
Venus, the brilliant evening "star", sets farther north
tonight, a few degrees farther north along the horizon than the Sun does
even on the date of the Summer solstice, June 21.
Tuesday, May 11
An hour after sunset, brilliant Mars in in SE, with the blue-white
first- magnitude star Spica just 5 degrees to its upper right. They'll be
within 2 degrees of each other from May 30 through June 15, and widen out
to 5 degrees apart again by the end of June.
An hour before sunrise on Wednesday, the waning crescent Moon is very
low, just 5 degrees S of east, while bright Jupiter, just risen about 13
degrees to Moon's lower left, is just above horizon 8 degrees N of east.
Wednesday, May 12
Last chance to see old Moon: Using binoculars about 40 minutes before
sunrise, look for the thin old crescent on horizon, about 5 degrees N of
east and 5 degrees below Jupiter.
Thursday, May 13
Tomorrow evening, from the latitude of East Lansing, MI (42.7 degrees
N), Sirius sets in WSW just one hour after sunset. You must look earlier
to see it! It's easier from S states.
The Cowboy Astronomer is in its final weekend at Abrams
Planetarium. Shows will be presented this Friday and Saturday at 8:00 p.m.,
and Sunday at 4:00 p.m. Rusty Rocket's Last Blast continues
Sundays at 2:30 p.m. through May 30; for more call (517) 355-4672.
Friday, May14 The Moon is New on Saturday morning at 8:05 a.m. EDT. This
is the closest New Moon of the year. Just three hours later the Moon passes
perigee, the closest point in its orbit, 221,887 miles from Earth. Some
coastal areas can expect extreme tides.
Saturday, May 15
With New Moon at 2:05 a.m. Hawaii time this morning, Hawaiians have
a chance to see the Moon about 17 hours past New this evening. Some 20 to
25 minutes after sunset, using binoculars, try for the very slender young
crescent 2 or 3 degrees above the horizon 16 degrees north of due west.
North America will have to wait until Sunday evening to see the young Moon.
Sunday, May 16
The young Moon is low in WNW at dusk, 23 degrees lower right of Venus,
or below Venus from southern U.S. As the sky darkens, look for earthshine
on the Moon's dark side, and look for a 3rd-mag. star, Epsilon in Gemini,
0.9 degree left of Venus. Look again on Monday and following evenings to
see how much the Moon and Venus shift nightly against the stars.
Monday, May 17
An hour after sunset, the Moon is in W to WNW, with brilliant Venus
10 degrees above. Betelgeuse, shoulder of Orion, is low in W, 12 degrees
to Moon's lower left. The 3rd-mag. star Epsilon in Gemini is about 3/4 degree
below Venus. The Gemini twins are 4-1/2 degrees apart, 12 or 13 degrees
above Venus. Pollux is the brighter twin, to the left of Castor.
Well up in SSE, Mars and bluish Spica are just 3-1/2 degrees part. Arcturus
is high in ESE, 30 degrees upper left of Mars. Telescopic views: The dark
surface feature Syrtis Major is near the center of the Martian disk at 8
p.m. EDT tonight, then 37 minutes later each night. In a few nights, or
several if you're in the far west, this feature will be favorably placed
on the Martian disk in late evening hours, when Mars is high in the sky.
Tuesday, May 18
About four hours before sunset, the crescent Moon is high
in the southern sky, with Venus within 7 degrees to its upper right. This
afternoon provides a fine chance to see Venus in the daytime. By sunset,
they're 8 degrees apart in the west, with Venus to the right of the Moon.
A telescope reveals Venus is now about five-eighths illuminated. Interesting
changes will take place in Venus' phase in coming months. As the sky darkens
tonight, look for Venus 8 degrees to the Moon's right, Pollux and Castor
11 degrees above them, and Procyon in WSW to W, 15 degrees to Moon's lower
left.
Wednesday, May 19
A pretty picture in the west as the sky darkens: A crescent Moon
with the Gemini twins, Pollux and Castor, 12 and 16 degrees to its right;
Venus about 11 degrees below the twins; and Procyon 15 degrees to Moon's
lower left.
Thursday, May 20
Moon is high in WSW an hour after sunset, with first-magnitude Regulus,
heart of Leo the Lion, some 14 degrees to its upper left. A special event
involving Moon and Regulus will occur Friday night. In the SSE tonight,
orange Mars and blue-white Spica are just 3 degrees apart, attracting the
attention of even casual skywatchers for the next several weeks.
To commemorate National Astronomy Day, which will occur on Saturday,
May 22, Abrams Planetarium presents two weekends of Summer Skies
(May 21-23 and 28-30), and public viewing sessions at Michigan State
University Observatory this Friday and Saturday, May 21 and 22, from
9 to 11 p.m. if sky is clear.
Summer Skies, a live planetarium show featuring celestial
events of coming months, will preview Venus at its brightest, Mercury, Mars,
and stars in the evening sky, the Milky Way at its best, August's Perseid
meteor shower, Jupiter and Saturn in the predawn, and the Harvest Moon.
Summer Skies will be presented at Abrams Planetarium May 21-23 and
28-30, on Friday and Saturday at 8 p.m. and Sunday at 4 p.m. Rusty
Rocket's Last Blast continues Sundays at 2:30 p.m. through May 30;
for more call (517) 355-4672. If you're out of our area, check with your
local planetarium, observatory, or astronomy club for Astronomy Day activities,
and join in!
Friday, May 21
Tonight in continental U.S. (48 states) and southern Canada, the
half-lit First Quarter Moon occults or covers Regulus. Time of star's
disappearance behind Moon's dark edge ranges from around sunset in state
of Washington to after midnight EDT in eastern U.S. Following are times
for selected cities when Regulus is suddenly "snuffed out" by
the leading dark edge of the Moon. PDT: Seattle 8:26 p.m. (in daylight);
San Francisco 8:54 p.m.; Los Angeles 9:11 p.m. MST: Tucson 9:18 p.m.
MDT: Denver 10:01 p.m. CDT: Chicago 11:09 p.m.; Austin TX
11:29 p.m. EDT: E Lansing MI and Toronto 12:10 a.m.; Boston 12:15
a.m.; Washington DC 12:19 a.m.; Atlanta 12:26 a.m.; Miami 12:42 a.m.
Use a telescope or binoculars to see star's disappearance at Moon's dark
edge and subsequent reappearance at bright edge. For more on this occultation,
visit the website http://www.lunar-occultations.com/iota
or see the article on pp. 109-110 of the May issue of Sky & Telescope,
which included maps for predicting times of disappearance and reappearance
for any location in the 48 states.
Tonight and Saturday evenings, Venus forms a nearly isosceles triangle
with Pollux and Castor, the Twins, 9 or 8 degrees above. Telescopes aimed
at Mars may reveal the dark surface feature Syrtis Major near the center
of the planet's disk around 10:30 p.m. EDT.
Summer Skies is presented 8 p.m. tonight at Abrams Planetarium,
followed by telescopic viewing at the Michigan State University Observatory
until 11 p.m., if sky is clear. Check Thursday's entry for other weekend
activities commemorating Astronomy Day.
Saturday, May 22
As the evening sky darkens, the waxing gibbous Moon is in the SW.
Note the star Regulus, which the Moon covered last night, is now 12 degrees
to Moon's lower right. Today is National Astronomy Day. To mark the
occasion, Abrams Planetarium presents Summer Skies at 8 p.m. tonight,
followed by telescopic viewing at the Michigan State University Observatory
from 9 p.m. until 11 p.m., if the sky is clear.
Sunday, May 23
Two shows at Abrams Planetarium today: Rusty Rocket's Last
Blast (our family show) at 2:30 p.m., and Summer Skies
at 4:00 p.m.
As the evening sky darkens, the Moon, just over two-thirds full, is well
up in WSW. Regulus is 25 degrees to the Moon's west, while the Mars- Spica
pair is about 30 degrees to the Moon's east.
Monday, May 24
The Moon is in the south at dusk, with Mars and Spica just 2-1/2
degrees apart in the SSE, 18 degrees to the Moon's lower left.
Tuesday, May 25
The Mars-Spica pair, now 2.4 degrees apart, is 7 or 8 degrees below
the Moon at dusk. Mercury is on the far side of the Sun today. Near the
point in its orbit closest to the Sun (perihelion), Mercury is in excellent
position to become visible in the evening sky within the next 7 to 10 days.
Stay tuned!
Wednesday, May 26
An hour after sunset, the striking Mars-Spica pair is just 2.3 degrees
apart in SSE, some 7 to 9 degrees to the right of the Moon.
Thursday, May 27
At nightfall, binoculars can split the star Zubenelgenubi, formerly
the southern claw of the Scorpion but now Alpha in Libra the Scales, into
a close pair of stars, of the 3rd and 5th magnitudes. Look for Alpha in
Libra in SSE, 4 or 5 degrees below the Moon. In WNW, to upper right of Venus,
Pollux and Castor are 4.5 degrees apart. Venus is the same distance lower
left of Pollux.
Friday, May 28
An hour after sunset, the Moon is in SE, with the bright Mars-Spica
"double star" some 30 degrees upper right, and Antares, heart
of the Scorpion, about 17 degrees lower left.
Saturday, May 29
This is the last day you can spot the Moon before sunset. Look about
15 minutes before sunset, and you'll note the Sun very low in WNW and the
"Planting Moon" just risen in ESE. An hour after sunset, look
for red Antares twinkling very low in SE, 9 degrees to Moon's lower right.
At the same time in WNW, brilliant Venus passes 4 degrees lower left of
Pollux. The Moon is Full overnight, at 2:30 a.m. EDT on Sunday morning (11:30
p.m. PDT on Saturday). This is the most distant Full Moon of this year.
By an hour before sunup on Sunday, Antares is low in SW, 8 degrees to Moon's
lower left.
Sunday, May 30
The Moon, just past Full, rises in ESE only about 20 minutes after
sunset as seen from lower Michigan and similar latitudes across the U.S.
As evening twilight deepens, note Antares in SE 12 degrees to the Moon's
right. In SSE, Mars and Spica are just 2 degrees apart, and still closing
slowly, until June 8. In the WNW, check the alignment of Venus-Pollux-Castor
nightly. In a few evenings they will lie in a straight line.
An hour before sunrise these mornings, bright Jupiter is low in E. Can
you spot Saturn rising 16 degrees to Jupiter's lower left?
Monday, May 31
Using binoculars about 20 minutes after sunset, try for Mercury
very low in bright twilight, 37 degrees to Venus' lower right and about
30 degrees north of due west. Mercury sets later each evening for first
three weeks of June, and has a very favorable appearance to lower right
of Venus; next month's Skywatcher's Diary and our illustrated
Sky Calendar will follow Mercury, Venus, and Mars in the evening
sky in June.
--------------------------------------------
Summer skywatching nights at Michigan State University
Observatory will be held on these Fridays and Saturdays, 9-11 p.m., weather
permitting: June 18, 19, and July 16, 17.
Please send any comments, suggestions, or questions to
David Batch: dbatch@msu.edu |