Astronomy in Pictures: Unraveling Galaxies and Clyde’s Spot


Expanded View of the Milky Way’s Core

Our view of the galactic center shows a tapestry of life and death. Stars are born and, with the fierce energy of youth, push out particle winds. Stars die, and their explosive ends blow out bubbles of hot gas. And in the middle of it all, our resident supermassive black hole (Sgr A*), a quiet 4 million-solar-mass behemoth, sets off flashes and plasma bursts of its own. How do all these sources weave together?

Galactic center
The galactic center is a busy place.
X-ray: NASA / CXC / UMass / Q.D. Wang; Radio: NRF / SARAO / MeerKAT

To see into our galaxy’s heart, scientists survey the region at shorter and longer wavelengths that can pass through the dust that blocks visible light. The image here builds on past panoramas with new observations that expand the view vertically, and allows us to observe our galaxy’s core as we’d never see it with our own eyes. Orange, green, blue and purple represent X-rays of increasing energy, as seen by the Chandra X-ray Observatory, while lilac and gray represent radio emission detected by the MeerKAT telescope in South Africa.

Among the more interesting participants of the melee pictured here are oddly linear threads of hot gas, such as the 20 light-year-long G0.17-0.41, which is held ramrod-straight by magnetic fields. Field lines from different sources may have gotten tangled up here before they snapped in a process called magnetic reconnection. Daniel Wang (University of Massachusetts, Amherst), who conducted the study, notes that threads like this one tend to lie near the edges of plumes of gas powered by supernovae, stellar winds, or Sgr A*’s outbursts.

Read more in the online preprint; the study will appear in the June Monthly Notices of the Royal Astronomical Society. See a fully annotated image in Chandra’s press release.

Unraveling Clyde’s Spot

Clyde's Spot evolution
The storm that was Clyde’s Spot has folded in on itself over the course of a year.
NASA / JPL-Caltech / SwRI / MSSS; Image processing by Kevin M. Gill © CC BY­­

Clyde’s Spot, a distinctive white spot southeast of the Great Red Spot, received its nickname in honor of amateur astronomer Clyde Foster of Centurion, South Africa. He discovered it using his 14-inch Schmidt-Cassegrain telescope on May 31, 2020, two days before NASA’s Juno mission was able to swing by for a closer look.

The initial white spot was a plume of methane-rich cloud material erupting above the top layers of the Jovian atmosphere. Later, the white spot faded and left behind a dark spot still visible in amateur scopes.

Now, a new image from Juno taken on April 15, 2021, shows that winds have stretched and pleated the spot into a folded filamentary region. These features are typically short-lived, disappearing quickly into the cloud decks, but due to its size this one might stick around for a while.

Read more about the latest image in NASA’s press release.

Hubble Views Lopsided Galaxy

NGC 2276
Hubble’s view of the lopsided spiral, NGC 2276
NASA / ESA / STScI / Paul Sell (Univ. of Florida);
Acknowledgment: Leo Shatz

The spiral galaxy NGC 2276 looks like it’s running away from something — the yellow-ish bulge of stars that ought to sit squarely at the galactic center instead lies off to the side. In fact, it isn’t the bulge that’s making the get-away. It’s the blue arms bursting with newborn stars that are being pulled toward another galaxy passing nearby: the aging elliptical NGC 2300.

NGC 2276 wide-field view
In this wide-field view, the blue galaxy on the left, NGC 2276. is being pulled by the neighboring galaxy on the right, NGC 2300.
NASA / ESA / STScI / Adam Block (Steward Observatory)

The galaxies’ colors are a study in contrasts: The spiral’s blue light comes from newborn stars. Some of these burn fast and die young; the galaxy has hosted six supernovae over the past six decades. It may also be home to an intermediate-mass black hole that’s 50,000 times the mass of the Sun. Meanwhile, the fuzzy elliptical has the yellow-white color of older stars. The pair are 120 million light-years away in Cepheus. Both galaxies are visible in backyard telescopes with surface brightness magnitudes of 13.5 (NGC 2276) and 12.8 (NGC 2300).

Read more in NASA’s press release, and find out how to see these galaxies and others near the celestial north in the February 2016 issue of Sky & Telescope.



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