To the reader:
The Skywatcher's Diary for June 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.
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 June issue, please send a long,
self-addressed stamped envelope to:
June 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/
Three evening planets: Brilliant Venus reaches greatest
elongation (maximum angular distance from Sun) June 11, and is easy
to spot in daylight! Just before sunset all month, look in W, about 45 degrees
upper left of setting Sun. Use telescope in afternoon or around sunset to
observe Venus' phase. On June 1, Venus is still slightly gibbous, 55 percent
full and 1/3 arcminute across. By month's end, Venus is a crescent, 37 percent
full and 1/2 arcminute across. Venus sets in WNW over 3 hours after sunset
June 1, and within 2-1/2 hours after sunset on June 30. Venus begins June
in Gemini, in line with "Twin" stars Castor and Pollux. Thereafter
Venus moves through Cancer into Leo, ending month 7 degrees lower right
of Regulus, the Lion's heart. Mars is bright orange "star"
in S to SSW at dusk, lingering within 2 degrees of bluish first-magnitude
Spica until mid-June. Use this occasion to compare their contrasting colors,
evident to unaided eye and greatly enhanced with binoculars. Closest approach
of Mars to Spica on June 8 is a "quasi-conjunction," because Mars
comes near star without passing directly N or S of it. By June 30, they
widen to 5 degrees apart. Mercury is very low in WNW at dusk all
month, to lower right of Venus, by 36 degrees on June 1 (look early!), by
24 degrees on June 15, and by 18 degrees on June 28 through July 5. Don't
miss this favorable appearance of Mercury!
Two planets at dawn: Bright Jupiter an hour before sunup
opens June low in E, and climbs higher toward ESE. Saturn opens month
very low, N of E, 16 degrees lower left of Jupiter, and ends month in E,
14 degrees to Jupiter's lower left.
Moon appears near planets on June 9-11 at dawn, and on June 14-17
and 21-23 at dusk. In Skywatcher's Diary, morning events are described
on the previous date.
Skywatcher's Diary: June 1999
Tuesday, June 1
An hour after sunset tonight and Wednesday, in W to WNW,
the heads of the Gemini twins are to the right of brilliant Venus, with
the planet and the two stars in a nearly straight line. Tonight Pollux is
5 degrees right of Venus, and Castor is 4-1/2 degrees right of Pollux. Bright
orange-colored Mars is in S, with blue-white Spica nearly 2 degrees lower
right. For the first week of June, Procyon, the "Little Dog Star",
is low in W 19 degrees lower left of Venus. Stars in the west get lower
each evening; on what date will you last see Procyon? The Moon rises farthest
south of east tonight, about two hours after sunset.
Wednesday, June 2
Thirty minutes after sunset, using binoculars, try for Mercury
very low in bright twilight, 35 degrees lower right of Venus and about 30
degrees north of due west. Can you see Mercury with unaided eye? It'll get
easier each evening, as it gets higher and sets later. As the sky darkens,
look for Pollux and Castor about 6 and 10 degrees to the right of Venus.
Mars-Spica are less than two degrees apart in the south.
Thursday, June 3
An hour before sunrise these mornings, Jupiter, brightest
morning "star", is low in east, with Saturn 16 degrees lower left.
At month's end these morning planets will be higher in the eastern sky and
a bit closer together, 14 degrees apart. By the time they disappear into
the western evening twilight glow late in April 2000, they'll be just 4
degrees apart.
Friday, June 4
Venus, Mercury, and Mars are all far brighter than any stars
visible in the current evening sky, but Mercury is hard to see in bright
twilight. The brightest stars visible an hour after sunset are: Arcturus
high in SSE; Vega in ENE; and Capella low in NW.
Saturday, June 5
Have you seen Mercury yet? It was behind the Sun on May
25, and is now visible about 45 minutes after sunset, 32 degrees lower right
of Venus, and very low, about 30 degrees north of due west. Mercury sets
a few minutes later each evening and is getting easier to see. Follow its
favorable apparition in coming weeks.
Sunday, June 6
On Monday an hour before sunrise, the Moon is in the SE
and is a few hours past Last Quarter phase. Note its left half is illuminated,
telling us that the Sun is below the NE horizon and nearly 90 degrees away.
Bright Jupiter is low in E, with Saturn nearly 16 degrees lower left. Watch
the Moon pass these planets later this week.
Monday, June 7
By forty-five minutes after sunset, Mercury may be visible
with unaided eye, 30 degrees lower right of Venus and about 30 degrees N
of due west. An hour after sunset, Mercury is a couple of degrees above
the horizon; it gets quite a bit easier to see this week. Tonight and Tuesday,
Mars and Spica are just 1.7 degrees apart in the south.
Tuesday, June 8
Don't miss the colorful Mars-Spica pair at its closest,
just 1.7 degrees apart in the south one hour after sunset. They'll gradually
spread apart in coming weeks, to 5 degrees by June 30, and 10 degrees by
July 14. On Wednesday an hour before sunup, look in ESE to E to find the
waning crescent Moon with Jupiter 11 degrees to its left. Saturn is 15 degrees
lower left of Jupiter.
Wednesday, June 9
An hour before sunup on Thursday, the waning crescent Moon
is low in E, with bright Jupiter 6 degrees upper right, and Saturn 11 degrees
lower left. Jupiter-Saturn are 15 degrees apart and closing.
Thursday, June 10
An hour before sunup on Friday, bright Jupiter is in E,
with the last easy-to-see old crescent Moon about 20 degrees to its lower
left. Saturn is about 5 degrees to the thin crescent Moon's upper right
and 15 degrees lower left of Jupiter.
Friday, June 11
Venus now appears 45 degrees from the Sun, its widest angle
away from the Sun during the current evening apparition, which lasts from
Nov. 1998 until early Aug. 1999. A telescope shows Venus is about half illuminated.
To reduce the glare of Venus against a darkening sky, observe Venus in daylight
or around sunset. Watch for interesting changes in Venus' phase and apparent
size as it swings toward Earth in coming weeks.
From southern states on Saturday about 40 minutes before sunrise, using
binoculars, try for the very thin old crescent Moon just risen, about 17
degrees N of east. Look 35 degrees lower left of Jupiter and 20 degrees
lower left of Saturn.
Saturday, June 12
An hour after sunset, Mercury is easy to see, low in WNW
26 degrees lower right of brilliant Venus. An hour later, use binoculars
to see the Beehive cluster of faint stars within one degree to Venus' lower
left. Mars and Spica are then 1.8 degrees apart in SSW.
Sunday, June 13
The Moon is New today at 3:03 p.m. EDT. An hour after sunset,
Mercury is low in WNW, 25 degrees lower right of Venus. Look for the Gemini
twins: Castor 11 degrees above Mercury, and Pollux, the brighter twin, 4-1/2
degrees left of Castor. In coming nights, watch the changing shape of the
triangle formed by Mercury, Pollux, and Castor.
Monday, June 14
About 30 minutes after sunset, look for the young crescent
Moon very low in WNW, about 28 degrees lower right of Venus. From eastern
U.S., the Moon's age (time elapsed since New) is less than 31 hours. As
the Moon sets and the sky darkens, look for Mercury 6 degrees above, and
Pollux and Castor, the heads of the Gemini twins, 10 degrees above Mercury.
Tonight Mercury-Pollux-Castor form an isosceles triangle.
Tuesday, June 15
An hour after sunset, the young crescent Moon is easy to
see in WNW, with brilliant Venus about 15 degrees upper left, and Mercury
about 11 degrees lower right. Mercury is 24 degrees lower right of Venus,
while Regulus is 20 degrees to Venus' upper left. The attractive Mars-Spica
pair is 2 degrees apart in S to SSW. The Summer Triangle is in NE to E.
Vega, its brightest and topmost star, is in ENE. Altair, the southern point
of the triangle, is low in E, 34 degrees lower right of Vega. Deneb is in
NE, 24 degrees to Vega's lower left. From now until early in August, the
Summer Triangle is visible all night.
Wednesday, June 16
Have you ever seen Venus in the daytime? This is a good
day to do it, using the Moon as a guide. Determine the time of local midday,
halfway between the times of sunrise and sunset, for your location. Venus
passes high, directly south, 3-1/4 hours after midday today. Venus is then
about 4 degrees upper left of the 3-day-old crescent Moon (or a little farther
for the East Coast, closer for the West Coast). By two hours before sunset,
Venus is in WSW, 45 degrees upper left of Sun and 3 or 4 degrees above the
lunar crescent. By sunset the Moon-Venus pair should be quite easy to see
in the west, with Venus about 3 degrees upper right of the Moon's crescent.
The Moon and Venus keep company for the rest of the evening, until moonset.
An hour after sunset, look for Mercury 23 degrees to the lower right of
the Moon and Venus.
Thursday, June 17
An hour after sunset, the crescent Moon is is west, with
Venus 12 degrees lower right and Regulus, heart of Leo the Lion, 6 degrees
upper left. Four weeks from tonight, on July 15, the Moon, Venus, and Regulus
will form a compact grouping, spectacular for naked eye and binoculars.
Keep track of all three objects until then.
Friday, June 18
An hour after sunset, the crescent Moon is one-third full
in WSW to W. Note three "stars" along a line from the Moon toward
the WNW horizon: Regulus 7 or 8 degrees lower right of the Moon, Venus 17
degrees lower right of Regulus, and Mercury 22 degrees lower right of Venus.
Extend the line from Mercury eastward past the Moon, and you'll find the
Mars-Spica pair within 2.4 degrees apart in SSW, and Antares, heart of Scorpius
the Scorpion, low in SSE.
Skywatching at Michigan State University Observatory is held tonight
and Saturday, 9-11 p.m. if sky is clear. Featured will be telescopic views
of Moon and deep-sky objects, and naked-eye views of stars and three planets,
including the alignment described above.
Saturday, June 19
This evening and Sunday, an hour after sunset, locate Mercury
low in WNW 21 or 22 degrees lower right of Venus. On both evenings, Pollux
is just over 5 degrees upper right of Mercury. Castor is 4-1/2 degrees to
the right of Pollux. This month, these stars are not as bright as Mercury,
so if you have difficulty seeing them, use binoculars.
Sunday, June 20
The Moon is at First Quarter phase today, 90 degrees or
one-quarter of a circle E of the Sun in the afternoon and evening sky. Shortly
after midday today (halfway from sunrise to sunset), look for the half-
illuminated Moon very low in E. At sunset the Moon stands well up in SSW.
Evenings around First Quarter are best for using binoculars or a telescope
to observe craters and other surface features along the lunar terminator
(day-night boundary).
Monday, June 21
Summer begins today at 3:49 p.m. EDT as the Sun stands
directly over the Tropic of Cancer, in the Pacific Ocean just W of Mexico's
Baha California. The Sun rises and sets farthest north today, and reaches
its greatest midday altitude of the year for anyone living north of the
Tropic of Cancer. An hour after sunset, Mars and Spica are still less than
3 degrees apart in SSW, within 12 degrees lower left of the waxing gibbous
Moon.
Tuesday, June 22
An hour after sunset in SSW, Mars-Spica are just 3 degrees
apart, some 5 to 7 degrees to Moon's lower right. Mercury is low in WNW,
20 degrees lower right of brilliant Venus.
Wednesday, June 23
An hour after sunset, Moon is in southern sky, with Mars-Spica
just over 3 degrees apart in SSW, 14 to 17 degrees to Moon's right. The
reddish star Antares, "rival of Mars" and heart of the Scorpion,
is in SSE, 31 degrees to Moon's lower left. In mid-September, Mars will
pass closely above its red rival. Keep track until then.
Thursday, June 24
An hour after sunset, Venus shines a little N of west,
with Mercury 19 degrees lower right. Mercury and the twins Pollux and Castor
to its right lie in a straight line, 12 degrees long. Regulus is 12 degrees
upper left of Venus. Antares is 20 degrees to Moon's lower left.
Friday, June 25
At nightfall, look for the head of Scorpius, a slightly
curved, nearly vertical line of three stars of 2nd and 3rd magnitude about
3 to 9 degrees to Moon's lower right. First-magnitude reddish Antares, heart
of the Scorpion, is 10 degrees to Moon's lower left.
Saturday, June 26
An hour after sunset, Mars and first-magnitude Spica are
now 4 degrees apart in SSW. Zero-magnitude Arcturus is 32 degrees above
the pair. First-magnitude Antares is in SSE, 10 degrees to the Moon's lower
right. In coming months, as Mars fades, compare its brightness to these
stars.
Sunday, June 27
An hour before sunrise these mornings, Saturn is in E,
14 degrees lower left of bright Jupiter. A line from Jupiter to Saturn,
extended 26 degrees to lower left, points to Aldebaran very low in ENE.
The Pleiades cluster, 17 degrees lower left of Saturn, is better seen an
hour earlier, before dawn brightens.
Monday, June 28
The southernmost Full Moon of this year rises in ESE shortly
before sunset today, crosses low in the south in the middle of the night,
and sets in WSW not long after sunrise on Tuesday. In the west an hour after
sunset tonight, Regulus is 9 degrees upper left of brilliant Venus. Mercury
is low in WNW, remaining 18 degrees lower right of Venus through July 5.
Tonight Mercury reaches its greatest angular distance from the Sun for this
time around, 26 degrees.
Tuesday, June 29
Within 45 minutes after sunset, or a little earlier from
northern U.S., watch for the Moon rising in ESE. This evening and Wednesday,
look for the star Altair, southernmost point of the Summer Triangle, about
30 degrees to the Moon's upper left.
Wednesday, June 30
At sunset, telescope and binoculars now show Venus as a
tiny fat crescent, 3/8 full and just 0.5 arcminute or 1/120 of a degree
across. (A magnification of 60-power would now make Venus appear half a
degree across, about as large as the Moon seen with unaided eye.) In the
west one hour after sunset, Regulus is visible just over 7 degrees to Venus'
upper left. In SSW, Mars and Spica have now spread to 5 degrees apart. Watch
Venus-Regulus and Mars-Spica in coming weeks, and watch for changes in their
separations.
***** end of Skywatcher's Diary for June 1999 *****