Sky & Telescope - November 2020 - 4

SPECTRUM

by Peter Tyson

Cozying Up to Our Star

The Essential Guide to Astronomy
Founded in 1941 by Charles A. Federer, Jr.
and Helen Spence Federer

WHEN IT COMES TO interactions with the Sun, survival depends

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NOVEMBER 2 02 0 * SK Y & TELESCOPE

EDITORIAL
Editor in Chief Peter Tyson
Senior Editors J. Kelly Beatty, Alan M. MacRobert
Science Editor Camille M. Carlisle
News Editor Monica Young
Associate Editor Sean Walker
Observing Editor Diana Hannikainen
Consulting Editor Gary Seronik
Editorial Assistant Sabrina Garvin
Senior Contributing Editors
Dennis di Cicco, Richard Tresch Fienberg,
Robert Naeye, Roger W. Sinnott
Contributing Editors
Howard Banich, Jim Bell, Trudy Bell, John E. Bortle,
Greg Bryant, Thomas A. Dobbins, Alan Dyer,
Tom Field, Tony Flanders, Ted Forte, Sue French,
Steve Gottlieb, David Grinspoon, Shannon Hall,
Ken Hewitt-White, Johnny Horne, Bob King,
Emily Lakdawalla, Rod Mollise, James Mullaney,
Donald W. Olson, Jerry Oltion, Joe Rao, Dean Regas,
Fred Schaaf, Govert Schilling, William Sheehan,
Mike Simmons, Mathew Wedel, Alan Whitman,
Charles A. Wood

N ASA / JOHNS HOPK INS A PL / N AVA L RESE A RCH L A B / PA RK ER SOL A R PROBE / BRENDA N G A LL AG HER

on getting close but not too close. We owe our very existence to
this sweet spot, with Earth basking in our solar system's Goldilocks
zone: neither too hot nor too cold but "just right" for life to thrive.
Comet NEOWISE, which we parade on our cover and in Associate Editor Sean Walker's photo essay on page 14, demonstrated this maxim to a
T. Comets that swing too near the Sun can split and ﬁ zzle, as Comet ATLAS did
earlier this year. Others that keep our star too much at arm's length can slip by
without becoming visually stunning. But Comet NEOWISE got it just right.
When it was discovered on March 27th, the comet was about magnitude 18.
By the time it emerged from its nearest brush with the Sun on July 3rd, it had
attained a mag of 0.5 to 1, easily visible to the naked eye. As our selection of
images reveals, thousands of observers across the world enjoyed this comet, the
brightest viewable from the Northern Hemisphere
since the mid-1990s' Comet Hale-Bopp.
Comet Biela, by contrast, might be one of those
icy visitors that, like Icarus, ﬂew too close to the
Sun. I say "might," because, as David Nakamoto
explains in his story on page 58, the fate of this
comet (ﬁrst identiﬁed in 1826) remains unclear.
Getting it just right: a Parker
Solar Probe image of Comet
Did it fragment into multiple pieces like Comet
NEOWISE, taken on July 5th,
Shoemaker-Levy 9 famously did in the 1990s? If so,
just after perihelion
does any large chunk of it survive to this day?
Even if the comet itself no longer exists, the meteor shower associated with
it might. In 1872, dust particles from Comet Biela put on one of history's best
meteor displays. In subsequent decades, this shower waned in intensity. But as
Joe Rao notes in his sidebar on page 63, astronomers recently detected a major
uptick in the comet's shower, with exciting possibilities for 2023 in particular.
Nothing takes the Goldilocks concept to such exacting extremes as the
Parker Solar Probe, however. As News Editor Monica Young describes starting
on page 20, this highly engineered spacecraft will journey right up to our star.
If the Earth-Sun distance were the 100 yards of an American football ﬁeld, the
probe's upcoming nearest approaches would have it straddling the 4-yard line.
Young will explain why we're sending this car-size spacecraft into the Sun's
very atmosphere, but consider for a moment one extraordinary fact about how:
The Sun-facing surface of the probe's heat shield will reach temperatures of
up to 1,370°C (2,500°F) on closest approach. Yet the instruments behind the
shield will remain at 29°C (85°F)! Human ingenuity, it
seems, knows no bounds, especially when it comes to getting things just right.

Contributing Photographers
P. K. Chen, Akira Fujii, Robert Gendler,
Babak Tafreshi

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Sky & Telescope - November 2020

Table of Contents for the Digital Edition of Sky & Telescope - November 2020