Wandering through the realms of the cosmos, pondering its huge vastness

Brighter Jupiter on its Closest Encounter with Earth

Make way for the King of the Planets! 🙂

Wondering what’s that big bright star that was visible all night?  It was the planet Jupiter, and it’s far brighter than any true star in the night sky. Jupiter can already be seen twinkling low in the east after twilight, and higher in the southeast as the evening wears on.

Even the skies seemed to be cloudy at night here in the Philippines,  Jupiter often still stands out amidst the dark sky. 😀

This giant gas planet is always bright, but it shines brighter this month. On the 21st (8PM PST), Jupiter will swing closer to Earth (368 million miles away) and shine brighter than at any time between 1963 and 2022 .  It will remain nearly this close and bright (magnitude -2.9) throughout the second half of September.

The night of its closest approach is also called “the night of opposition” because Jupiter will be opposite the sun, rising at sunset and soaring overhead at midnight. This opposition is special because Jupiter, the largest of all the solar system’s planets, will soon reach perihelion, the closest point in its orbit to the Sun. That means it’s physically closer to Earth during this opposition than a normal one. It will rise below the Circlet asterism in the constellation Pisces the Fish and present its best views high in the sky, when its light travels through less of Earth’s atmosphere.

Jupiter is also brighter than usual by about 4 percent because one of its brown cloud belts is hidden. For nearly a year the giant planet’s South Equatorial Belt, usually plain to see in a small telescope, has been hidden under a layer of bright white ammonia clouds.

Because Jupiter is so close to Earth, this is a great opportunity to view it through a telescope. Jupiter is most interesting when the Gred Red Spot is visible and/or when one of the moons is casting a shadow on Jupiter’s disk.

Coincidentally, the planet Uranus is also at opposition on September 21st. On that night it will travel across the sky alongside Jupiter, although not nearly so bright. With binoculars or telescopes, it will be less than 1° from Jupiter until September 24. At magnitude 5.7, Uranus is the brightest “star” that’s that distance roughly north of Jupiter, and it can be recognized by its bluish color.
The full moon will appear right above Jupiter on September 23, which is also the Autumnal Equinox.

Happy sky viewing! 😀

* * * * * *

Fast facts about Jupiter

  • Jupiter is the largest planet in the solar system. More than 1,000 Earths could fit inside Jupiter, and all the other planets together make up only about 70 percent of Jupiter’s volume.
  • It takes Jupiter about 12 years to orbit the Sun once, but only about 10 hours to rotate completely, making it the fastest-spinning of all the solar system’s planets.
  • Jupiter rotates so rapidly that its polar diameter, 41,600 miles (66,900 kilometers), is only 93 percent of its equatorial diameter, 44,400 miles (71,500 km).
  • Jupiter reflects 52 percent of the sunlight falling on it, more than any other planet except Venus (65 percent).
  • Jupiter’s four bright moons, Io, Europa, Ganymede, and Callisto, are easily visible through small telescopes. Io takes less than 2 days to orbit, so its relative position visibly changes in an hour or so — less when it appears close to Jupiter.
  • Our line of sight lies in the plane of the jovian moons’ orbits, so we see occultations (when a moon moves behind Jupiter), eclipses (when Jupiter’s shadow falls on a moon), and transits (when a moon passes in front of Jupiter) at various times.
  • Jupiter’s moon Ganymede is the solar system’s largest satellite, with a diameter of nearly 3,300 miles (5,300 km), greater than that of Mercury.


sources: SkyandTelescope.com, Spacedaily.com, Astronomy.com

2 responses

  1. Pingback: Jupiter Celebration September 2010 « Michael W. Peterson

  2. Pingback: Tweets that mention Brighter Jupiter on its Closest Encounter with Earth « Journey to the Stars -- Topsy.com

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