Month: July 2024

Major Farside Solar Flare

/ Dr.Tony Phillips / Leave a comment

July 25, 2024: The biggest flare of Solar Cycle 25 just exploded from the farside of the sun. X-ray detectors on Europe’s Solar Orbiter (SolO) spacecraft registered an X14 category blast:

Solar Orbiter was over the farside of the sun when the explosion occured on July 23rd, in perfect position to observe a flare otherwise invisible from Earth.

“From the estimated GOES class, it was the largest flare so far,” says Samuel Krucker of UC Berkeley. Krucker is the principal investigator for STIX, an X-ray telescope on SolO which can detect solar flares and classify them on the same scale as NOAA’s GOES satellites. “Other large flares we’ve detected are from May 20, 2024 (X12) and July 17, 2023 (X10). All of these have come from the back side of the sun.”

Meanwhile on the Earthside of the sun, the largest flare so far registered X8.9 on May 14, 2024. SolO has detected at least three larger farside explosions, which means our planet has been dodging a lot of bullets.

The X14 farside flare was indeed a major event. It hurled a massive CME into space, shown here in a coronagraph movie from the Solar and Heliospheric Observatory (SOHO):

The CME sprayed energetic particles all over the solar system. Earth itself was hit by ‘hard’ protons (E > 100 MeV) despite being on the opposite side of the sun.

“This is a big one–a 360 degree event,” says George Ho of the Southwest Research Institute, principal investigator for one of the energetic particle detectors onboard SolO. “It also caused a high dosage at Mars.”

SolO was squarely in the crosshairs of the CME, and on July 24th it experienced a direct hit. In a matter of minutes, particle counts jumped almost a thousand-fold as the spacecraft was peppered by a hail storm energetic ions and electrons.

“This is something we call an ‘Energetic Storm Particle’ (ESP) event,” explains Ho. “It’s when particles are locally accelerated in the CME’s shock front [to energies higher than a typical solar radiation storm]. An ESP event around Earth in March 1989 caused the Great Quebec Blackout.”

So that’s what might have happened if the CME hit Earth instead of SolO. Maybe next time. The source of this blast will rotate around to face our planet a week to 10 days from now, so stay tuned. Solar flare alerts: SMS Text

The “Inevitable” Fragmentation of Comet Tsuchinshan-ATLAS

/ Dr.Tony Phillips / Leave a comment

July 12, 2024: Comet Tsuchinshan-ATLAS (C/2023 A3) is about to fall apart. It’s “inevitable,” according to a new study by astronomer Zdenek Sekanina. “Evidence suggests that the comet has entered an advanced phase of fragmentation,” he writes.

Above: Comet Tsuchinshan-ATLAS photographed by José J. Chambó

If true, this is disappointing news. Discovered in early 2023, the comet appears to be heading for a magnificent close encounter with the sun later this year, perhaps becoming as bright as Venus in October 2024. Instead, it could fall apart before it has a chance to become a naked-eye object.

Sekanina’s arguments are threefold: First, the comet has failed to brighten as it approaches the sun. Second, the comet’s orbit seems to be affected by a “non-gravitational acceleration.” This could happen if, say, inner jets are pushing apart a disintegrating nucleus. Third, the comet’s dust tail has an unusually narrow, teardrop shape with a peculiar orientation. 

Together, these observations suggest a crumbling comet “in which increasing numbers of fractured refractory solids stay assembled in dark, porous blobs of exotic shape, becoming undetectable as they gradually disperse in space,” says Sekanina.

Above: This is what a break-up looks like–Comet LINEAR 24 years ago.

“That is a fascinating paper,” says Nick James, director of the Comet Section of the British Astronomical Association. “Sekanina is very well respected in the field, so it carries a lot of weight. To use ‘inevitable’ in any prediction about a comet may be unwise! But it is definitely a testable theory and another good reason to observe this comet at every opportunity.”

In fact, James isn’t convinced. In an independent data set, he finds no evidence of non-gravitational accelerations. “This doesn’t look like a comet that is fragmenting to me,” he says.

We’ll soon find out. The comet is brighter than 10th magnitude, well within range of mid-sized backyard telescopes, which means amateur astronomers can monitor the potential break-up. Point your optics here.