Every 20 years, Jupiter appears to overtake Saturn. The next occasion will be on May 28, 2000, but their closest pairing on that date will be lost in the glare of morning twilight, except from the tropics and middle southern latitudes. Groupings of planets earlier that month will also be lost in the Sun's glare. But as the two giant planets appear to move very slowly, they appear rather close together for a few years, making possible the simultaneous sighting of as many as four or five bright planets, sometimes all in the same part of the sky. Here is a summary of the visible planet gatherings through mid-2002:
Nov. 1999-Apr. 2000 at dusk. From early November 1999 through mid-April 2000, all three bright outer planets are continuously visible in evening twilight, spanning 120° on November 4, shrinking to 60° on January 16, 30° on February 27, and to a minimum of just 5° in mid-April. An appearance of Mercury in early February brings the total to four planets simultaneously visible. A crescent Moon adds its special beauty, sweeping past the planets Feb. 6-11, Mar. 8-10, and Apr. 5-6. The gathering of Mars-Jupiter-Saturn in the western sky, fitting within a 6° field Apr. 6-17 and into 5° Apr. 14 and 15, is more compact than any grouping of the three bright outer planets within a 179-year interval, between December 1901 and November 2080.
Jun.-Nov. 2000 at dawn. In early June 2000, as Jupiter and Saturn emerge from the solar glare into the eastern morning twilight glow, they appear closer together than they'll be again until the approach of their next pairing, 0.1° apart, on the evening of December 21, 2020. Jupiter-Saturn are separated by 1.5° on June 6, 2° on June 13, and 3° on June 23. The old crescent Moon passes by on the mornings of June 28 and 29. Mercury's appearance in late July and early August brings the naked-eye planet total to three, and binoculars make it possible to spot a fourth, Mars, emerging near departing Mercury around August 10. On Sept. 18, the lineup of three bright outer planets expands to 90°. In October, Jupiter-Saturn widen to 11° apart. A fine appearance of Mercury in November's morning twilight brings the total of naked-eye planets to four, spanning the sky almost from ESE to WNW horizon.
Jan.-Jun. 2001 at dusk. In late January 2001, Jupiter and Saturn have closed to 7° apart in Taurus, well up in SE as evening twilight deepens, while Mercury and Venus are in excellent view in WSW to SW. Mercury sinks into the twilight glow in early February, followed by Venus in late March, leaving just the two giant planets in view during all of April. Mercury returns to evening twilight for most of May, presenting a very favorable appearance. Mercury overtakes Saturn on May 6, the pair located 13° lower right of Jupiter. As Mercury overtakes Jupiter on May 15, Saturn has already disappeared into the twilight glow. On May 21, as Mercury reaches greatest elongation, Jupiter is still visible 6° below. On June 13, Mars reaches an unusually bright opposition in SE, but by then all the other planets have disappeared.
Jul.-Nov. 2001 at dawn. In early July 2001, Mercury and Jupiter emerge into morning twilight, joining Venus and Saturn already in view. Before midmonth, four planets and a star form two separate groupings in ENE to E: Mercury-Jupiter, and Venus-Saturn-Aldebaran. The old crescent Moon sweeps past on July 17-19. Mercury is gone before the end of July. Venus-Jupiter form a brilliant pair near the feet of Gemini August 5 and 6, while Saturn remains near Aldebaran. The 3-planet span expands as Venus moves rapidly eastward. By mid-October, Venus is in Virgo low in E, Jupiter is in Gemini high in S, and Saturn-Aldebaran in Taurus are high in WSW. In late October to mid-November, Mercury in its very favorable apparition lingers in a prolonged close pairing with Venus in ESE and again brings the total to four planets visible. Mercury sinks back into bright twilight in mid-November, followed by Venus in early December, leaving Saturn and Jupiter still in view, on the opposite side of the sky, W to WNW.
Jan.-Jun. 2002 at dusk. In early January 2002, four planets are in favorable view in evening twilight: Mercury low in WSW, Mars high in SSW, Saturn high in ENE to E still in Taurus near Aldebaran, and Jupiter in ENE in Gemini. Mercury disappears in January's third week, but after Venus emerges from the twilight glow in late February, at least four planets are visible at dusk continuously until late May. In late April and early May, during Mercury's best appearance of the year, all five naked-eye planets are visible simultaneously in the western sky. The five-planet span is 54° on April 20, 40° on Apr. 30, and 36° on May 5. Jupiter excluded, the remaining four planets, all in Taurus, fit into 13° on April 30, shrinking to a minimum of 9° on May 7, and then Mercury fades rapidly in May's second week. Compact planet arrangements occur on Apr. 30 (Mercury 6° lower right of Venus); May 3 (Mars 2.2° N of Saturn); May 5 (compact triangle of Venus-Mars-Saturn less than 3° on a side); May 6 (Venus 2.4° N of Saturn); May 10 (Venus 0.3° N of Mars); and June 3 (Venus 1.7° N of Jupiter, with Mars 13° to their lower right). By then, Mercury and Saturn have disappeared, and all three remaining planets are in Gemini. In late June, Mars is closing in on Jupiter, but both sink into the solar glare before their mutual conjunction, leaving Venus as the only evening "star."
SUMMARY (Abstract)
This planetarium demonstration emphasizes visible gatherings of naked-eye planets, rather than the widely-publicized events of May 2000 which are lost in the solar glare. Five sequences of snapshots of the entire sky at dusk or dawn are presented:
Nov. 1999-Apr. 2000 at dusk. Four planets in simultaneous view in Feb. 2000, and Mars-Jupiter-Saturn gathering into a rare compact trio in April.
Jun.-Nov. 2000 at dawn. Jupiter-Saturn in early June emerging from their once-in-20-years close pairing, and four planets in simultaneous view in Nov. 2000.
Jan.-Jun. 2001 at dusk. Four planets in late January, and Mercury passing Saturn and Jupiter in May.
Jul.-Nov. 2001 at dawn. Two gatherings, Mercury-Jupiter, and Venus-Saturn-Aldebaran, reward early risers before mid-July. A close pairing of Venus-Jupiter in early August, then another chance to see four planets at once in late October to mid-November.
Jan.-Jun. 2002 at dusk. Four planets line up across the sky in early January. Then we fast-forward to late April and early May to watch all five bright planets in spectacular display in the western sky, featuring several planet pairs and a compact trio. After two of the planets depart, Venus-Jupiter form a brilliant pair on June 3.
