Jupiter Shines On as Saturn's Rings Go Flat

In September's planetary opera, Jupiter remains sharp, and Saturn's ring cycle goes flat.

Jupiter is ascending the east-southeastern sky at dusk. This large gaseous planet is brilliant (negative second magnitude) and is easily visible from light-polluted urban locations. On Sept. 1, you'll see a fat moon to the upper right of Jupiter, and on the next night, the moon will be to the planet's left. Lunacy continues, as the scene repeats itself four weeks later. On Sept. 28, the moon will be to Jupiter's upper right, and on Sept. 29, the moon will be to the planet's left. All month, you watch the bright Jupiter traverse the southern sky toward the west most of the night.

Saturn is a different story. For the first time since the mid-1990s, this planet's famous rings appear flat. We've watched the southern view of Saturn's rings for the past decade and a half. Now, we'll cycle through the northern side of the rings until 2025.

Right now, we're in transition with Saturn's rings. Earth officially passes through Saturn's ring plane Sept. 4, thus making the rings appear edge-on to us. Don't worry about watching the flattened rings, as Saturn appears too close to the sun now, and the brilliant solar rays wash out hope of visibility. The large ringed planet begins to emerge in October's sky.

Though dim, Mars rises in the east-northeast about 1:30 a.m. and is high in the eastern sky before dawn. The red planet -- loitering with the twins in the Gemini constellation -- is a first magnitude object now, but gets slightly brighter through September.

Effervescent and ever bubbly, Venus rises shortly after 4 a.m. in the east-northeast, hanging out in the constellation Cancer early in September. Later in the month, Venus rises in the east ahead of the sun, and it will move to the constellation Leo. It's a strong, negative third magnitude planet (brilliant), and you'll be able to spot it through light-polluted skies. But when the sun comes up, Venus gets washed out.

During the Earth's annual orbit around the sun, the sun appears to cross our equator -- from the northern into the southern hemisphere. That is the moment that fall begins for the northern hemisphere, and the Autumnal Equinox occurs Sept. 22 at 5:18 p.m. EDT, according to the U.S. Naval Observatory.

Earthly Events

-- Sept. 5 -- Rosemary Killen of the Goddard Space Flight Center discusses the National Lunar Science Institute at the open house at the University of Maryland Observatory, College Park. Afterward, enjoy the sky through a large telescope, weather permitting. 9 p.m. 301-405-6555; http://www.astro.umd.edu/openhouse.

-- Sept. 12 -- Astrophysicist John Chambers of the Carnegie Institution of Washington lectures on "How Jupiter and Saturn Influenced the Development of the Solar System" at the regular meeting of the National Capital Astronomers, University of Maryland observatory. 7:30 p.m. http://www.capitalastronomers.org.

-- Sept. 13 -- Learn about galaxies far, far away. Amber Straughn of the Goddard Space Flight Center talks about using Hubble Space Telescope data for galaxy research at the regular meeting of the Northern Virginia Astronomy Club. Enterprise Hall, Room 80, George Mason University, Fairfax. http://www.novac.com.