Astronomy - USA (2022-06)

60 ASTRONOMY • JUNE 2022

SECRET SKY

Technology is amazing. Take the sharing of

the Dec. 4, 2021, total solar eclipse. The event

occurred over a remote stretch of Antarctica

and its surrounding seas, allowing a limited travel audi-

ence. But thanks to the efforts of Theo Boris and

Christian Lockwood of the JM Pasachoff

2021 Antarctic Expedition, untold numbers

of viewers got to experience it live by stream-

ing their eclipse feed on http://www.nasa.gov/live

and YouTube from Union Glacier, Antarctica.

My wife Deborah Carter and I were among

them, and we were grateful for it — especially

as an unusual eclipse phenomenon occurred.

A fiery ghost

What caught our attention was the sudden

appearance of what at first looked like a

white solar prominence on the Sun’s left limb

in the moments before second contact (the

beginning of totality). The feature material-

ized from the solar glare just as Baily’s beads

began to mix with pink jewels from the Sun’s

chromosphere. Then, after the diamond ring

f lashed into view, an arched prominence,

rich pink in color, blossomed next to the

diamond. Seeing that deep pink color only

enhanced the striking white feature.

After less than a minute of totality, the

limb of the Sun emerged and consumed the white mys-

tery feature. Throughout totality, no other phenomenon

matched its intensity, which was much brighter than

the surrounding corona. I wondered if the white feature

was an artifact of the live transmission, but Zev Hoover

of the Pasachoff Expedition assured me it was not.

A couple of days later, Deborah received a series of

images from eclipse enthusiast Larry Shore of Mesa,

Arizona, who experienced totality at the Antarctic

Logistics and Expeditions camp on Union Glacier with

the TravelQuest tour. The white feature was in his

images as well, confirming the reality of this fiery ghost.

White hot plasma

Petr Horálek, a Czech astrophotographer who observed

the eclipse from an altitude of 41,000 feet (12,500

meters) aboard a Boeing 787-8 Dreamliner, wrote on

his website that the solar corona was “truly ‘wild,’ espe-

cially on its left part,” where “hot plasma was visible to

the unaided eyes.” The plasma came from an active

region on the solar limb, “which itself was enough to be

visible as a very bright ‘pearl’ above the eclipsed Sun.”

Horálek directed me to images from the NASA Solar

Dynamics Orbiter and the ESA Solar and Heliospheric

Observatory. They show the active region at the white

feature’s position and, above it, what appear to be loops

illuminated by hot plasma f lowing along magnetic field

lines.

The Sun’s active regions mainly consist of closed

ma g net ic loops , i n wh ich pla sma i s con f i ned a nd g lows

brightly. Horálek notes, however, that the Sun experi-

enced small f lares in the hours before the eclipse that

lasted throughout the event. While the gas in

the Sun’s corona normally has a temperature

of a few million degrees, solar f lare tempera-

tures can range between 18 million and

36 million degrees Fahrenheit (10 million

and 20 million degrees Celsius). This may be

why, during the eclipse, the hot plasma in the

magnetic loops appeared so much more

intense than the surrounding corona.

What ’s a stou nd i ng is t he r a r it y of c atch i ng

such an event on the Sun’s limb during the

brief moments of totality — especially given

that the Sun is just emerging from its latest

minimum and active regions still remain

relatively sparse. Horálek says that there may

be a higher chance of catching a similar event

during the 2023, 2024, 2026 (and maybe

2027) total solar eclipses, when solar activity

will be closer to its peak.

Thanks to the JM Pasachoff Antarctic

Expedition livestream, eclipse lovers the

world over got to witness a rare total solar

eclipse event from the comfort of home. But

if you were one of the lucky few who viewed the eclipse

from Antarctica and got to view the feature through

binoculars or a telescope, I’d love to hear your visual

impressions at [email protected].

A total eclipse

rarity

This ghostly white prominence dazzled

viewers in Antarctica and online.

ABOVE LEFT: A white

solar phenomenon

appeared on the left

limb of the Sun, seen

here moments into

totality, with rich pink

prominences visible

at upper right.

SCREENSHOTS FROM VIDEO BY

THEO BORIS AND CHRISTIAN

LOCKWOOD OF THE JM PASACHOFF

ANTARCTIC EXPEDITION/NASA

ABOVE RIGHT: The

hot plasma feature is

visible in this extreme

ultraviolet image

taken by NASA’s Solar

Dynamics Observatory.

NASA

CENTER: Faint

chromospheric

activity is visible at

the base of the white

feature in this image

taken from Antarctica.

LARRY SHORE

What’s

astounding

is the rarity

of catching

such an

event during

the brief

moments of

totality.

BY STEPHEN

JAMES O’MEARA

Stephen is a globe-

trotting observer who

is always looking

for the next great

celestial event.

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