Aug. 30, 2023 (Spaceweather.com): Tonight, a quirky mixture of science, hyperbole and folklore will cause millions of people to go outside and stare at the sky. We’re talking about the Super Blue Moon. This is what it will look like:

Above: The supermoon of July 14, 2022, photographed by Oliver Schwenn of Aarhus, Denmark [full story]

No, it won’t be blue. The supermoon on Wednesday evening, Aug. 30th, will look a lot like any ordinary full Moon. However, there are three things that make it special.

First, the science: This week’s full Moon is the biggest and brightest of 2023. Astronomers call it a “perigee moon.” The Moon’s orbit is an ellipse with one side (“perigee”) about 50,000 km closer than the other (“apogee”). Full Moons that occur on the perigee side of the Moon’s orbit are extra big and bright. This week’s Moon will become full within 9 hours of perigee, making it the closest full Moon of the year (357,181 km away).

Next, the hyperbole: About 10 years ago, many science journalists and even some astronomers started calling perigee Moons “supermoons.” A supermoon is 8% bigger and 15% brighter than an average full Moon. Would you call Clark Kent “super” if he were only 8% faster and 15% stronger than an average human? No, but let’s roll with it! People love super things.

Finally, the folklore: You’ve probably heard the expression “Once in a blue Moon.” It means “rare.” Modern folklore provides a more precise definition. When there are two full Moons in a calendar month, the second one is “blue.” Such blue moons come along every 2 to 3 years. August already had one full Moon on Aug. 2nd; now it is about to have another (blue) one on Aug. 30th.

Don’t take “blue” too literally. Most blue Moons are pale gray when they are high in the sky, or orange when they are rising and setting. However, if the Moon *does* turn blue, it could mean that a volcano is erupting or a wildfire is nearby. Run!

In summary, this week’s Super Blue Moon will be about 15% bigger than an average moon and, in the eye of the beholder, immeasurably prettier. Go out after sunset on Aug. 30th, look east, and watch it rise into the darkening summer sky. If you take a picture, submit it here.

Aug. 23, 2023 (Spaceweather.com): A new paper in the research journal Icarus offers dramatic proof that solar activity can affect planetary weather. The big surprise: The planet is Neptune, 2.5 billion miles from the sun. Images taken by the Hubble Space Telescope over a period of 28 years show bright clouds forming in sync with the 11-year solar cycle:

The connection between Neptune and solar activity is surprising to planetary scientists because Neptune is our solar system’s farthest major planet. It receives only 0.1% of the sunlight we get on Earth. Yet Neptune’s cloudy weather seems to be driven by solar activity, and not the planet’s four seasons, which each last approximately 40 years.

Other planets in our solar system don’t behave this way. While clouds on Earth may be influenced by the solar cycle, the modulation is no more than a few percent; and even that small amount is controversial. Neptune’s clouds, on the other hand, are bright, flamboyant and global. Their correlation with the solar cycle is obvious at a glance.

Chavez and her colleagues believe they have an explanation.

“Our findings support the theory that the sun’s ultraviolet rays, when strong enough, may be triggering a photochemical reaction that ultimately leads to high-altitude clouds on Neptune,” says Imke de Pater, emeritus professor of astronomy at UC Berkeley and a senior co-author of the study.

Their paper describes how UV rays from the sun (which are strongest when the sunspot number is high) penetrate Neptune’s upper atmosphere and break apart molecules of methane gas. This sets off a chemical reaction yielding hydrocarbons (C𝑥H𝑦). If these hydrocarbons sink into the atmosphere, they could condense to form hazes and clouds.

Above: 21 years of images from the Keck Observatory in Hawaii confirm Hubble’s observations. [more]

Why doesn’t this happen on every planet? “Neptune is unique,” says de Pater. Unlike other planets in our solar system, Neptune has a lot of methane in its stratosphere. (How it gets there is a mystery, but that’s another story.) Solar UV rays have little trouble reaching the gas and kick-starting cloud formation.

Based on the data so far, it seems to take about two years for Neptune’s clouds to fully form once the solar cycle reaches its peak. Solar Cycle 25 is rising now with a peak expected in 2024. This means Neptune’s cloudy season is about to begin. Stay tuned.

Aug. 7, 2023: (Spaceweather.com) Observing Venus this week may be one of the most dangerous things you can do with a telescope. The planet is only 12 degrees from the blinding sun. The results, however, are undeniably beautiful:

Philip Smith took this picture in broad daylight on Aug. 6th from his home in Manorville, NY. “This is exactly how it looked,” he says. “The colors have not been altered.”

Like the Moon, Venus has phases, and at the moment it is a marvelously thin crescent. This happens during a special time called “inferior conjunction” when Venus passes between the sun and Earth. This year’s inferior conjunction is less than a week away on Aug. 13th–so now is primetime for catching the crescent.

Smith explains how he did it: “The hardest part was finding Venus with the sun so nearby. I put solar filters on my telescope and started with the sun to get a good sharp focus. Then I had the telescope go to Venus. I took off the finder scope’s solar filter first and put my hand behind it to make sure the sun was not in its path. Then I removed the main telescope’s solar filter–and all was good!”

At closest approach on Aug. 13th, Venus and the sun will be separated by a little more than 7 degrees. This means careful daytime shots of Venus will be possible throughout the conjunction. Got a picture? Submit it here.

more images: from Mariano Ribas of Buenos Aires, Argentina; from Daniel Mello of Rio de Janeiro, Brazil; from Robert Spellman of Apple Valley, CA; from Bum-Suk Yeom of Iksan, South Korea; from Philippe Tosi of Nîmes, France

more observing tips: from Sky & Telescope

July 25, 2023: (Spaceweather.com) Until a few days ago, Comet 12P/Pons-Brooks looked like a perfectly ordinary comet. Then, something on its surface exploded. Now it resembles “the fastest hunk of junk in the galaxy”–the Millennium Falcon:

These images are hot off the press (July 25.434) from the Comet Chasers, a team of researchers led by Helen Usher of Cardiff/The Open Universities. They are using telescopes at the Las Cumbres Observatory network to monitor this comet’s unusual eruption.

The action began on July 20th when the comet abruptly brightnened 100-fold. Astronomers watched as double plumes of debris streamed out of the comet’s core, sweeping back to form the Falcon shape. It is now shining with about the same brightness as an 11th magnitude star, making it an easy target for mid-sized backyard telescopes.

Comet 12P/Pons-Brooks is famous for exploding. Discovered in 1812 by Pons and discovered again in 1883 by Brooks, the bursty comet visits the inner solar system every 71 years. Since the 19th century at least seven significant outbursts have been observed.

At the Astronomical Station Vidojevica in Serbia, astronomers Igor Smolić and Marco Grazdanovic took a closer look using the station’s big 1.4 meter telescope:

“This is a 60x30s exposure,” says Smolić. “[It reveals the origin of the ‘horns’ curving out of the comet’s compact core].”

Richard Miles of the British Astronomical Association thinks 12P may be one of 10 to 20 known comets with active ice volcanoes. The “magma” is a cold mixture of liquid hydrocarbons and dissolved gasses, all trapped beneath a surface which has the consistency of wax. These bottled-up volatiles love to explode when sunlight opens a fissure.

The best may be yet to come. The comet is currently beyond the orbit of Mars, but falling toward the sun for a close encounter in April 2024. At that time it is expected to become a naked-eye object at 4th or 5th magnitude.The timing is significant because 12P will reach maximum brightness only a few days before the total solar eclipse on April 8, 2024. Sky watchers in the path of totality could look up and see an outburst for themselves.

Amateur astronomers are encouraged to monitor developments. Comet 12P is currently crossing the head of Draco not far from the north celestial pole. Check out those horns! And submit your photos here.

more images: from Thomas Wildoner of Weatherly, PA; from David Strange of Salcombe Regis, East Devon, UK