April 15, 2002
in Evening Sky
Griffith Observatory Presss Release
RIVER PARK -- The five
naked-eye planets gather in the west in the evening sky during the
last half of April and the first three weeks of May, and this is
a rare opportunity to see five planets simultaneously.
The moon joins four planets in mid-April
and then joins all five on May 13, 14, and 15.
The planets orbit the sun, each at its
own speed, and from earth they appear to move around the sky against
the background of stars. Generally one or two planets are visible
at any given time, but seldom can you see five at once.
The last time all five naked-eye planets
were visible together in the evening sky was in December, 1997,
and the next time will not be until March and April of 2004.
The much-publicized grouping of planets
that happened in May 2000, and that some announced would cause the
earth to fall over, was not visible because the sun was in the same
part of the sky.
The most interesting nights are May 13
through 15 when the five planets plus the moon are strung out in
a line in the western sky. Illustrations follow at the end of the
text. April 1 - 14 Four planets are visible in the evening sky.
Venus is prominent low in the west as twilight ends. Jupiter is
nearly overhead at the same time.
Saturn is midway between Jupiter and Venus,
and Mars is approximately mid-way between Saturn and Venus. The
bright star a short distance south of Saturn is Aldebaran, the eye
of Taurus the Bull.
The moon is very near Venus on April 14th.
April 15 - 21 On about April 15th, Mercury becomes visible during
early evening twilight as it moves out of the glare of the sun,
and it joins the other four planets.
By the 17th, Mercury appears below and
slightly to the right of Venus. Mercury is moving westward (higher)
relative to the other planets night by night, and the distance between
it and Venus decreases until they are only 6 degrees apart on April
30th and May 1st (which is as close as they come).
Mercury remains visible until it moves
too nearly in line with the sun, by May 20th. From bottom to top
(or west to east), Mercury, Venus, Mars, and Saturn are about equally
spaced, although they are not equally bright. Jupiter is a considerably
higher. The moon is very near Mars on the 15th, Saturn on the 16th,
and Jupiter on the 18th. April 22 - 30 Mercury is higher and sets
later, and so it is easier to see the five naked-eye planets all
Look during the half-hour after 8 p.m. (The sky is too light before
8 p.m. and Mercury is too low after 8:30 p.m.) From bottom to top
(or west to east) the planets are Mercury, Venus, Saturn, and Jupiter.
Saturn, Aldebaran, and Mars (in descending
order of brightness) form a small equilateral triangle 5 degrees
on a side for the few nights around the 23rd. Watch Venus approach
Mars and Saturn night by night. May 1 - 12.
As May begins, Mercury, Venus, Mars, and
Saturn (and Aldebaran) span less than 12 degrees of the sky and
continue to bunch up closer while Jupiter is 28 degrees above (east
of) Saturn. (The total span of the five planets is 39 degrees on
Mars passes 2 degrees from Saturn on the
nights of the 2nd and 3rd. On the 5th, Venus, Saturn, and Mars form
a small triangle only 2-1/2 degrees on a side and for several days
these three planets can be seen together in binoculars. Venus passes
closest to Saturn on the 6th. Venus is less than 1/2 degree from
Mars on the nights of the 9th and 10th, and then you can see both
together through a low-power telescope. By the 12th the planets,
in order from bottom to top (or west to east), are Mercury, Saturn,
Mars, and Venus. Aldebaran is 7 degrees below Saturn and has become
lost in the sunŐs glare. May 13 - 16. The moon joins the five planets
on these four nights. The moon passes each in sequence.
The thin crescent moon is between Mercury
and Saturn on the 13th, 1-1/2 degree from Venus on the 14th, two-thirds
of the way from Venus to Jupiter on the 15th, and above Jupiter
on the 16th.
The four planets Mercury, Saturn, Mars,
and Venus span 15 degrees while Jupiter is 20 degrees above (east
of) Venus (the total span of the five planets is 33 degrees). Mercury
has faded and become hard to see.
Venus, Jupiter, and the bright orange star
Betelgeuse in Orion (to the south) form an equilateral triangle
about 20 degrees on a side.
May 17 - 31 Mercury is moving between the
earth and sun, and by about the 17th it moves too close to the sun
be seen any longer. Its disappearance leaves, in order from bottom
to top, Saturn, Mars, Venus, and Jupiter visible from the end of
On the 24th these four planets are roughly
equally spaced, but Saturn is moving toward the sun. It fades from
view on about that date. As May ends, attention turns to brilliant
Venus and very bright Jupiter as the separation between them narrows
noticeably night by night due to the rapid eastward motion of Venus.
They are 9 degrees apart on the evening of the 25th (Venus is mid-way
between Mars and Jupiter then), and only 3 degrees apart on the
31st. Venus passes Jupiter in a magnificent conjunction on the nights
of the 2nd and 3rd, when the two brightest planets are less than
2 degrees apart.
This planetary grouping spans nearly two
months in time. It is a series of events with several highlights,
and it is an excellent opportunity to watch their motions in the
sky and to see change from night to night. It can be enjoyed from
an urban area as long as the western horizon is not blocked. A telescope
does not help, but binoculars will enhance the view.
During these weeks Comet Ikeya-Zhang is
easily visible in binoculars in the morning sky. It is expected
to remain visible with binoculars through May. For additional information
on this planetary grouping and other astronomical events, including
Comet Ikeya-Zhang, please call the Sky Report at (323) 663-8171
( at http://www.GriffithObs.org/skyreport.html).
The Observatory, including its telescope,
is closed for renovation and expansion until 2005, but people are
welcome to watch the planets on their own from the Observatory lawn
Other excellent web sites that discuss
this gathering are the Carnegie Science Center Astronomical Calendar,
"2002 Spring Planets" and Bonanza for Planet Watchers. April 14-18,
8:00 p.m. PDT: Mercury is visible with great difficulty at 7:40
p.m., but by 8:00 it is setting.
The thin crescent moon is near Venus on
the 14th, near Mars on the 15th, near Saturn on the 16th, and near
Jupiter on the 18th. April 23, 8:00 p.m.: Mercury has joined the
other four naked-eye planets. Saturn, Mars, and the star Aldebaran
form a small equilateral triangle. May 5, 8:00 p.m.: The five naked-eye
planets plus the star Aldebaran (left of Mercury) span 36° in the
early evening sky. May 13-15, 8:00 p.m.: The crescent moon joins
the planets on the evenings of the 13th, when it is between Saturn
and Mercury, on the 14th, when it is near Venus, and on the 15th,
when it is near Jupiter.
The moon is above Jupiter on the 16th.
The five planets span 34°. May 24, 8:15 p.m.: Mercury is moving
between the earth and sun and can no longer be seen and Saturn is
too low to see easily; the five-planet grouping has ended. Watch
Venus approach Jupiter. June 2, 9:00 p.m.: Jupiter and Venus are
in close conjunction. [Graphics created with Starry Night Pro from
http://www.Siennasoft.com and modified by Observatory Art Director
Links on this planet gathering: Carnegie
Science Center's Astronomical Calendar [http://CarnegieScienceCenter.org/exhibits/planet_calendar.asp]
2002 Spring Planets at: http://analyzer.depaul.edu/paperplate/2002%20Spring%20Planets.htm
Viewer's Guide: Moon Joins the Great
Planet Alignment (includes animatiion) at: http://www.space.com/spacewatch/planets_moon_020412-1.html
See a Rare Dance of Planets at: http://SkyandTelescope.com/observing/objects/planets/article_572_1.asp
Bonanza for Planet Watchers at: http://www.pa.msu.edu/abrams/SkyCalendar/Bonanza.pdf