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Astro Bob: Webb wows with first Neptune photo / Aurora alert

NASA's flagship infrared telescope captures an amazing view of Neptune's rings. Watch for aurora on Thursday, Sept. 22.

Neptune by Webb
NASA's James Webb Space Telescope captured this photo of Neptune, its rings and several of the planet's moons with its near-infrared camera. Triton, the bright spot of light in the upper left of this image, far outshines the planet because Neptune's atmosphere contains methane which absorbs infrared light.
Contributed / Space Telescope Science Institute, NASA, ESA, CSA, and STScI
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I couldn't wait to share this new Webb image of the planet Neptune and its satellites. Part of my excitement stems from having looked at the planet just last night with my community education astronomy class. Several of the students remarked on the planet's blue color. Neptune is located about 10 degrees southwest of Jupiter in the constellation Aquarius and visible in binoculars from a reasonably dark sky. I'm planning a separate post on how to find it soon.

Neptune and moons
Neptune has 14 known satellites, seven of them visible and labeled here. The planet's five principle rings are dark, dusty and likely made of ice particles coated with organic compounds reddened by radiation from the sun.
Contributed / Space Telescope Science Institut/NASA, ESA, CSA, and STScI

The very thing that makes the planet so colorful — methane gas — is the reason the planet's globe appears dim compared to Triton. Methane absorbs infrared light. Triton's about a quarter the size of our own moon and looks bright because it has next to no atmosphere — just a few whiffs of nitrogen and methane.

Triton is the only large moon in the solar system to orbit its planet backwards. Astronomers suspect it was originally an icy asteroid from the Kuiper Belt that was captured by Neptune's gravity. The eighth and outermost planet is 17 times more massive than Earth and nearly four times as large, making it the biggest player in the outer solar system.

Neptune clouds
Methane-ice clouds show as bright streaks and spots, which reflect sunlight before methane gas absorbs it. A subtle band of brightness circling the planet’s equator could be a sign of the global atmospheric circulation that powers Neptune’s winds and storms. The atmosphere descends and warms at the equator, the reason it glows more than the surrounding, cooler gases.
Contributed / NASA, ESA, CSA, STScI

But the rings ! So lacy and beautiful. You'll never see them in any but the largest telescopes because they're extremely dark and spindly compared to the chunky water-ice found in Saturn's rings. They're made of fine dust — primarily ice particles coated in organic compounds darkened by solar radiation. These new photos are the best made in decades of a planet so remote it takes its light 4 hours to get here.

Aurora Sept 2
The aurora has already appeared several times this month including on Sept. 2, when red-topped, green rays danced above the northern horizon.
Contributed / Bob King

In other space news, we may get a visit from the northern lights on Thursday night, Sept. 22. An opening in the sun's outer atmosphere, the corona, is flinging solar electrons and protons at us like an egged house on Halloween. The material is expected to arrive and possibly link into Earth's magnetic field and fire up the aurora between about 10 p.m. and 1 a.m. that evening.

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Sunspots
The sun continues to "stay busy" producing a steady stream of sunspot groups. This photo, taken around 10 a.m. Wednesday morning, Sept. 21, shows the current bunch. Regions 3105 and 3106 just rotated around the front side and could spawn flares.
Contributed / Bob King

For the moment, forecasters expect a minor G1 storm, with lights visible across the Upper Midwest in the lower half of the northern sky. I'll update on my Facebook page, facebook.com/astrobobking . I suspect solar activity will soon pick up as a couple of large sunspot groups recently rotated around to the sun's front side. These may grow large enough to be visible to the naked eye through a safe solar filter like a #14 welder's glass.

Read more from Astro Bob
The prototype BlueWalker 3 satellite that will usher in space-based, broadband cell service is now easily visible with the naked eye. Get ready. More than 100 even brighter satellites are planned.

Related Topics: SCIENCE AND NATURE
"Astro" Bob King is a freelance writer and retired photographer for the Duluth News Tribune. You can reach him at nightsky55@gmail.com.
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