April 15, 2002
Planets Gather
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 at once.
     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 the 1st).
     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 evening twilight.
     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 through May.
     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 Don Dixon.]
     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

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