Wayne Independent - Honesdale, PA
  • LOOKING UP: See Uranus next door to Jupiter

  • Basking in the glow of its big neighbor Jupiter, you can see another planet the next clear night, in the same view with binoculars.

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  • Basking in the glow of its big neighbor Jupiter, you can see another planet the next clear night, in the same view with binoculars.
    Currently trailing closely with Jupiter is the planet Uranus.
    These two worlds, along with Saturn and Neptune, make up the gas giants in our Solar System’s family of planets. They are immense by earthly standards. The Earth is not quite 8,000 miles wide. Compare that to the fifth planet Jupiter, booming at 87,000 miles across at the equator; sixth from the Sun is Saturn, still a titan at 72,000 miles. Uranus and Neptune are 31,000 and 33,000 miles wide, respectively- and as the spacecraft flies.
    We would expect Jupiter to dominate the night sky among the planets given its brilliance. In fact, only Venus is brighter, and only at certain times.
    Jupiter is shining at magnitude -2.9, brighter than any nighttime star. Its bright white light is unmistakable, as it rises in the eastern sky during the evening this month. The great light is so visible although the planet is on average, 483.3 million miles from the Sun (about 380 million miles from Earth at its closest).
    Uranus, however, is much dimmer. The 7th planet is presently magnitude +5.7; its average distance from the Sun is 1,783 million miles (nearly 2 BILLION).
    On the magnitude scale, the faintest star most people can see on a very dark, clear night in the countryside is +6. While possible to see Uranus with eyes alone, it escaped detection until 1781 when astronomer Sir William Herschell stumbled upon it with his telescope. At nearly 6th magnitude, it easily blends in with a host of faint stars.
    Binoculars, however, will show it readily. This is an excellent time to look for it, with Jupiter as a guidepost. Between now and early December, the pair are close together, gradually shifting east to west against the background stars. Jupiter, being closer, gradually overtakes Uranus. Yet in this whole time, both will fit within one field of view of binoculars. They appear closest together- in conjunction, on Sept. 18 when they are 0.8 degree apart. For comparison, the full Moon spans about 0.5 degree.
    With binoculars, Uranus appears as a dim but easily seen “star” just above brilliant Jupiter. No other stars of like brightness are close by, to confuse identifying Uranus.
    They reach “opposition” on the same night, Sept. 21- when they are on the opposite side of the sky from the Sun. On that date they rise at approximately the same time the Sun sets, and are in the sky all night long.
    While a small telescope easily shows the disc of Jupiter with some details of its cloud bands and spots, the disc of Uranus appears much smaller. A telescope magnifying 100x or more will show that Uranus is more than a star-like point of light. Resolving it as a clean, circular disc isn’t easy because of air turbulence. It may appear slightly greenish or bluish, but more likely, gray.
    Page 2 of 2 - Neptune is visible in the southern sky on September evenings this year, also visible in binoculars. Much farther out (averaging 2,793 million miles), the 8th planet appears as magnitude +7.8. Binoculars show it as a faint star among many dim stars. a good finder chart is needed to pick it out. Sky & Telescope Magazine (Sept. 2010 issue) and web site (skyandtelescope.com) contain charts for both outer planets.
    The bright Moon will stand above Jupiter and Uranus on Sept. 22; full Moon is on Sept. 23rd.
    Send your notes to news@neagle.com. Let me know if you find Uranus.
    Keep looking up!
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