Abrams Planetarium Skywatcher's Diary
March 1998
To the reader
The Skywatcher's Diary for March 1998 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 Sky Calendar from a previous month is available
over the Internet. It can be viewed via a World-Wide Web browser at
http://www.pa.msu.edu/abrams/SkyCalendar/Index-t.html
If you would like a printed sample of the March issue, send a long,
self-addressed stamped envelope to:
March Sky Calendar
Abrams Planetarium
Michigan State University
East Lansing, MI 48824
Each month, the Department of Physics and Astronomy at Michigan State
University also makes Skywatcher's Diary available over the Internet.
It can be accessed with a World-Wide Web browser at
http://www.pa.msu.edu/abrams/SWD/Diary.html
The Skywatcher's Diary is also available via anonymous ftp at:
ftp://www.pa.msu.edu/pub/swd/
Special event on March 4: Moon covers Aldebaran; see March 2-4 in
Diary below.
Planets: Saturn is the highest evening planet for most of March,
25 degrees up in WSW at dusk at start of month, sinking to horizon just
N of W by month's end. Mercury emerges very low in W at dusk, to
lower right of Mars by end of first week, and fades quickly in 4th week.
Mars is very low in W at dusk, sinking to horizon by month's end.
Faint Mars is 20 degrees lower right of Saturn on March 1, just 1 degree
left of Mercury on March 10, and is the lowest of the three planets for
rest of month. Our Sky Calendar shows all three planets together
daily March 6-19, March 21-23, 26, and 28-30. Watch for changes in their
arrangement! Binoculars will be useful for locating faint Mars, for seeing
Mercury near the beginning and end of its apparition, and for following
Saturn late in month as it sinks into the twilight glow. All three will
be gone by month's end.
At dawn, Venus is brilliant in SE to ESE all month. The crescent
Moon is nearby on March 24, as described on March 23 in Skywatcher's
Diary below. Jupiter emerges to Venus' lower left late in month.
On March 26, from certain parts of eastern U.S. and Canada, Moon
covers or uncovers Jupiter just after moonrise! See March 25 in Diary.
Skywatcher's Diary: March 1998
Sunday, March 1
A beautiful crescent Moon is in WSW at dusk. As sky darkens, find Saturn
about 8 degrees to Moon's lower right, and fainter Mars 20 degrees to Saturn's
lower right. A telescope shows the rings of Saturn, tipped 11 degrees from
edge-on.
Monday, March 2
Orion, the Hunter, well up in the south an hour after sunset in early March,
helps locate several other constellations and bright stars. Orion's pattern
is easy to recognize: "Three stars in a row, and two stars above, two below."
Three stars of 2nd-magnitude in a short, nearly straight line mark his
belt. Orion's two brightest stars, on opposite sides of the belt, are reddish
Betelgeuse, marking a shoulder, and blue-white Rigel, marking a foot. Follow
Orion's belt to the lower left to find Sirius, the Dog Star, brightest
in the night sky. (The planet Venus, now in the morning, appears much brighter.)
Extend Orion's belt in the opposite direction to find the orange star Aldebaran,
the eye of Taurus, the Bull. Early on Wednesday evening, the Moon will
occult or cover this star for observers in most of eastern half of U.S.
The International Occultation Timing Association (IOTA) would like to receive
videos of the March 4 occultation of Aldebaran, taken by camcorders to
obtain precise timings. For more information, see pp. 98-100 of the March
issue of Sky & Telescope, and the IOTA website at: http://www.sky.net/~robinson/iotandx.htm
Tuesday, March 3
Tonight the Moon is high in the southwestern sky at dusk. Last evening,
we found the star Aldebaran by extending Orion's belt to the upper right.
Early this evening that star is 14 degrees to the Moon's upper left. Only
one day to go until the Moon covers the Bull's eye! As the sky darkens,
look for the Pleiades star cluster, also called the Seven Sisters, 14 degrees
to the right of Aldebaran and 10 degrees to the Moon's upper right.
Wednesday, March 4
Early this evening, the Moon occults or covers Aldebaran after sunset
from everywhere in U.S. and Canada south of the N limit "graze line", from
southeastern SD, through southern MN, across center of WI, northern lower
MI, and Ontario to N border of NY-VT-NH, across center of ME, to southern
Nova Scotia. (Graze line stays within 10 miles of lat 45 degrees N all the
way from eastern WI to western ME.) Aldebaran disappears at Moon's dark
limb around sunset along line through Sioux Falls SD, Des Moines, Memphis,
and Biloxi MS. From places farther east, sky is darker when Moon's leading
dark edge covers Aldebaran: It's mid-twilight (Sun 9 degrees down) along
line through Green Bay-Cincinnati-Tampa, and nautical twilight (Sun 12 degrees
down) from eastern lower MI, central OH, Charleston WV, Charlotte NC, Miami.
For Northeast U.S., star will disappear after twilight ends. Reappearance
(R) of Aldebaran at Moon's bright limb (for which a telescope will
be needed) is near sunset in SD, NE, western parts of KS, OK, TX. R is
in mid-twilight along line from central WI through Des Moines, Kansas City,
eastern KS, OK, TX. R is at nautical twilight from N lower MI, through
central MO and easternmost TX. Still farther east, sky is darker.
For times for a long list of cities in the US and Canada, see the map
on p. 99 of March Sky & Telescope, or check the IOTA website
at: http://www.sky.net/~robinson/iotandx.htm
In lower Michigan, the leading dark edge of the Moon snuffs out the
star at times ranging from 7:18 p.m. EST in the extreme SW corner of the
state, through 7:25 p.m. in Lansing, 7:30 p.m. in Bay City, to within a
minute or two of 7:45 p.m. at the northern limit. Time of reappearance
in Michigan ranges from near 7:45 p.m. at the northern limit, 8:05 p.m.
in Lansing, to 8:10 p.m. in the extreme SE corner of the state.
Thursday, March 5
An hour after sunset, the Moon is high in south, with Aldebaran 13 degrees
to the Moon's west, and Betelgeuse nearly as far to the Moon's lower left.
For the rest of this week, the Moon joins Betelgeuse inside the huge Winter
Hexagon, comprised, in clockwise order, of the stars Aldebaran, Rigel,
Sirius, Procyon, Pollux, Castor, and Capella. Through binoculars and telescopes
tonight, the trio of craters Ptolemaeus, Alphonsus, and Arzachel stand
out along the terminator (day-night boundary), below the Moon's center.
The smallest, southernmost, deepest and youngest crater of the three is
Arzachel, about 60 miles across and over 2.5 miles deep, with a large multiple
central "mountain" easily seen in binoculars. Beginning at sunset, carefully
watch these craters for 6 hours, and hour by hour you'll notice sunlight
illuminating progressively more of their floors and the central peak of
Arzachel. Look again on Friday evening. For a day-by-day description of
lunar surface features through the course of a lunar month, see the book,
"Exploring the Moon Through Binoculars and Small Telescopes" by Ernest
H. Cherrington, Jr.
Friday, March 6
An hour after sunset, locate the waxing gibbous Moon high in SSE, with
Betelgeuse, shoulder of Orion, 13 degrees to its upper right. Pollux and
Castor, the Gemini Twins, are 20 degrees from Moon, and Procyon, in the
Little Dog, is 22 degrees to Moon's lower left.
Milky Way Legacy continues at Abrams Planetarium. Tour our amazing home
galaxy with noted author Ken Croswell and emerge with a clearer view of
our home in space. Find out some of the ways the Milky Way is very special,
and how, unlike most galaxies, it is equipped to create the variety of
ingredients needed for life. Showtimes are Fridays and Saturdays at 8 p.m.,
Sundays at 4 p.m., through August 2.
Saturday, March 7
Forty-five minutes after sunset, using binoculars, scan the horizon very
nearly due west for two planets within a single field of view: Bright Mercury
just over 3 degrees lower right of Mars. In three days they'll be just
one degree apart. Saturn is 16 degrees to Mars's upper left. Look nightly
and watch for changes. The three bright stars near the Moon tonight, in
order of brightness, are: Procyon, Pollux, and Castor.
Sunday, March 8
WSKY ... Radio Station of the Stars, Sundays 2:30 p.m. at Abrams
Planetarium.
Forty-five minutes after sunset, very nearly due west, bright Mercury
is 2.2 degrees lower right of Mars. Binoculars give the best view of planets
low in bright twilight.
Monday, March 9
Forty-five minutes after sunset, very nearly due west, bright Mercury is
1.3 degrees lower right of Mars. Saturn is 15 degrees to Mars's upper left.
Binoculars may be needed to see faint Mars.
Tuesday, March 10
Forty-five minutes after sunset, about 5 degrees above the horizon, very
nearly due west, bright Mercury is just one degree right of Mars. Saturn
is within 15 degrees to their upper left. Regulus, heart of Leo, the Lion,
is 3 degrees to Moon's lower left. Look hourly over several hours tonight
to detect the Moon's motion against the background stars.
Wednesday, March 11
At dusk, find Mercury very low, nearly due west, with faint Mars 1.5 degrees
to its lower left, and Saturn 13 degrees to its upper left. In east, Regulus
is 9 degrees above Moon.
Thursday, March 12
The Moon is Full tonight, and is up all night. Look for Sun and Moon on
opposite horizons just before sunset tonight and just after sunrise on
Friday. At dusk Mercury is very low, nearly due west, with faint Mars 2.2
degrees lower left, and Saturn nearly 12 degrees upper left. Tonight the
Moon passes through the penumbra, or outermost part of Earth's shadow,
and a subtle shading may be detected on the S limb of the Moon's disk around
deepest eclipse, at 11:20 p.m. EST.
Friday, March 13
About 40 minutes after sunset from mid-Michigan, the Moon has just cleared
the horizon, due east. Mercury is due west, with faint Mars 3 degrees lower
left, and Saturn 10 degrees upper left.
Saturday, March 14
Forty-five minutes after sunset, there are three planets low in the west:
Mercury, with faint Mars nearly 4 degrees below, and Saturn 9 degrees upper
left. Three hours after sunset, look in ESE for the star Spica about 9
degrees below the Moon. You can also locate Spica by following the curve
of the Big Dipper's handle: "Follow the arc to Arcturus and drive a spike
to Spica." By dawn Moon and Spica will be in the southwest, nearly 3 degrees
closer, with Spica to Moon's lower left.
Sunday, March 15
At dusk, find Mercury low in W, with Mars 4.5 degrees below and Saturn
8 degrees upper left. Wait until nightfall (after Mars and Mercury have
both set tonight), and from very dark sites Mar. 15-28, the zodiacal
light may appear as a huge, nearly vertical cone of dim light in W.
How far from the Sun can you detect its glow? Saturn, just above W horizon
at nightfall, is 25 degrees from the Sun, and the Pleiades and Aldebaran
are now respectively 65 and 75 degrees from Sun. From a superb dark site,
you may even be able to trace the zodiacal light past the horns of Taurus,
now almost 90 degrees from Sun. For more on this phenomenon, see http://antwrp.gsfc.nasa.gov/apod/ap970826.html
Monday, March 16
At dusk, Mercury is low in west, with faint Mars 5 degrees below and Saturn
7 degrees upper left.
Tuesday, March 17
Although the spring equinox is still three days away, the length of day
today, from sunrise to sunset, is already 12 hours. There are two reasons
for this: First, sunrise and sunset times are calculated for when the top
of the solar disk, rather than its center, appears on the horizon. Second,
refraction by the Earth's atmosphere bends light and makes the rising or
setting Sun appear about one solar diameter higher than it actually is.
The combination of the two effects lengthens the day by about 9 minutes
in middle latitudes.
Wednesday, March 18
This evening, low in west about 45 minutes after sunset, three planets
form a roughly isosceles triangle: Bright Mercury with faint Mars about
6 degrees below, and Saturn about 6 degrees upper left.
An hour before sunup on Thursday, the Moon is in S, with Antares, heart
of the Scorpion, 9 degrees below.
Thursday, March 19
Mercury reaches its greatest apparent angular distance from the Sun in
the evening sky this time around, 19 degrees. Find Mercury low in W at
dusk, with faint Mars 6 degrees below, and Saturn 5 degrees upper left.
Friday, March 20
Equinox occurs today at 2:55 p.m. EST, as Sun appears to move northward
across Earth's equator. Spring begins in our northern hemisphere.
Moon reaches Last Quarter phase Saturday morning, 90 degrees or one-
quarter circle west of Sun. At sunrise, note the Moon's left half is illuminated.
Saturday, March 21
Low in west at dusk, Mercury is 5 degrees right of Saturn, their least
separation. Faint Mars is 7 degrees below. On Sunday evening, the three
planets form an isosceles triangle, with Mars, lowest, at the apex. By
Monday, Mercury is expected to fade to equal Saturn.
Sunday, March 22
An hour before sunrise on Monday, the crescent Moon is in SE with brilliant
Venus within 17 degrees lower left. Be sure to look again on Tuesday.
Monday, March 23
In predawn on Tuesday, a beautiful pairing of Moon and Venus --
the two brightest nighttime objects -- rewards early risers. Circumstances
vary with location. From Lansing, Michigan, Venus rises 4 degrees to Moon's
lower left at 4:37 a.m. EST, nearly 2 hours before sunrise. From most locations
in U.S. the views of Moon and Venus should be especially striking about
an hour before sunup. Follow Tuesday's pairing well into daytime, even
past midday! Later that day, as seen from Southwest U.S., Moon passes narrowly
south of Venus around 12:30 p.m. PST (1:30 p.m. MST). From parts of south
Texas, Louisiana, and Mississippi, Moon hides Venus soon after 2 p.m. CST,
not long before moonset. For a listing of times for various cities in that
region, visit IOTA's Occultation website at: http://www.sky.net/~robinson/iotandx.htm
Tuesday, March 24
Forty minutes before sunrise on Wednesday, the old crescent Moon is in
ESE, 9 degrees to lower left of Venus. Using binoculars, watch for the
rising of Jupiter, 14 degrees to Moon's lower left. You'll need a place
with an unobstructed view of the horizon. Note the time you first spot
Jupiter, and look three minutes earlier on Thursday, and you'll find Jupiter
in very nearly the same place, provided it isn't behind the Moon then from
your location. More tomorrow.
Wednesday, March 25
On Thursday, March 26, in morning twilight from E side of FL peninsula,
eastern GA, most of SC, central NC, through VA and WV and central OH to
eastern lower Michigan and southwestern Ontario, the dark side of the Moon
uncovers Jupiter in morning twilight, just after moonrise! From places
farther east, sky is brighter as Jupiter appears. From eastern New England,
Moon covers Jupiter just after moonrise and uncovers it after sunrise.
Time Jupiter is uncovered ranges from 5:23 a.m. in Miami, to 5:30
a.m. at the FL-GA border, to 5:45 a.m. from Philadelphia to SE corner of
MI. In the next 5 minutes until 5:50 a.m., Jupiter is uncovered across
eastern MI, states of PA and NJ, Lakes Erie, Huron, and Ontario, and most
of NY State. For times of occultation, see pp. 98-100 of March Sky
& Telescope magazine, or visit IOTA's Occultation website at: http://www.sky.net/~robinson/iotandx.htm
Thursday, March 26
In twilight about 45 minutes after sunset, here's another isosceles triangle
of planets, this time with Mercury (mag. +1.4) at apex. Saturn (+0.6) and
Mars (+1.3, maybe too low to see) are about 5.5 degrees to lower left.
Using binoculars, look very low, just N of due W.
In SE at dawn on Friday, Venus reaches greatest elongation, 46 degrees
from Sun. Viewed through a telescope, Venus now shows a roughly "half moon"
phase.
Friday, March 27
The Moon is New today at 10:14 p.m. EST and is not visible. This is the
closest New Moon of the year, with Moon at perigee, 357,025 km from Earth,
at 2 a.m. EST on Saturday.
Saturday, March 28
Using binoculars about 30 minutes after sunset, try for the first young
crescent Moon, very low, nearly due west. In Michigan, some 21 hours have
passed since New Moon. Saturn is close by to Moon's upper right. Faint
Mars is 3.3 degrees to Saturn's lower right, and Mercury, even fainter
at mag. +2.0, is within 6 degrees upper right of Saturn. The planets are
just about gone!
Sunday, March 29
The young Moon is easy for unaided eye, low in W at dusk. If you see one
planet, it'll be Saturn, 14 degrees to Moon's lower right.
On Monday morning, 45 minutes before sunup, try for Jupiter, rising
10-12 degrees S of due east, 20 degrees lower left of Venus.
Monday, March 30
In SSW at dusk, Sirius, in Canis Major, the Great Dog, is the brightest
star in evening sky. Venus and Jupiter are the brightest morning objects,
although Jupiter is still very low in twilight. In a few weeks, Venus,
Jupiter, and the Moon will form a rare compact gathering of the three brightest
nighttime objects. You can follow the action with the drawings and text
on our April Sky Calendar.
Tuesday, March 31
Twenty-seven days have gone by since the occultation of Aldebaran on March
4, and the Moon has nearly made it around again. (The orbital period of
revolution of the Moon, measured with respect to the stars, is called the
sidereal period, 27.3 days.) This time, as the sky darkens, note
the star Aldebaran a few degrees to Moon's upper left, and the 4th-mag.
star Gamma Tauri at the lower point of the V-shaped grouping of the Hyades
and Aldebaran. Gamma is 4 degrees lower right of Aldebaran. Tonight from
many locations within the U.S., the Moon will occult Gamma Tauri, a beautiful
sight for binoculars.
