Sky & Telescope - July 2020 - 10

NEWS NOTES
GALAXIES

How Fast Does the Milky
Way's Warp Whirl?
ASTRONOMERS HAVE KNOWN for
decades that, while the inner part of the
Milky Way is ﬂat as a very thin pancake, gases in the outer edges warp out
of the galactic plane. The stars in the
outskirts follow suit, riding like boats
up and down the wave. Now, scientists
have measured those vertical motions,
using the European Space Agency's
Gaia satellite to gauge how quickly the
warp whirls around the Milky Way. The
results appeared online March 2nd in
Nature Astronomy.
Gaia is mapping the positions and
motions of more than a billion Milky
Way stars (S&T: Aug. 2018, p. 9), and
last year scientists used its data to precisely chart the warp's shape (S&T: Nov.
2019, p. 12). With the new study, Eloisa
Poggio (National Institute of Astrophysics, Italy) and colleagues again turned
to Gaia to see how that warp precesses,
or turns, around the center.
Poggio and colleagues measured the
vertical motions of more than 12.6 mil-

lion giant stars from the Gaia catalog,
which gave the researchers insight into
the motions of the warp itself. They
found that the warp is turning prograde,
in the direction of the galaxy's rotation,
at a speed of about 10 km/s per kiloparsec away from the galactic center.
Out at the Sun's location, the warp is
precessing at 80 km/s - so our Sun,
which goes around the galactic center
at some 230 km/s, is fast outpacing the
wave it rides. While the Sun takes some
220 million years to circle the galaxy,

IN BRIEF

2020 Star Party Status

Astronomer Margaret Burbidge, who
celebrated her 100th birthday last year,
has passed away. An early fascination
with the stars combined with a talent for
mathematics - as well as a stubbornness
that enabled her to overcome prejudice
- ultimately led to a fruitful career. Most
famously, together with her husband,
Geoffrey Burbidge, and collaborators
Fred Hoyle and William Fowler, Burbidge
published the seminal paper "Synthesis of
the Elements in Stars." The study outlines
how stars forge elements via fusion in
their cores, cementing the idea that most
of the elements around us originated in
the stars. Read the fascinating story of
her life and work in the July 2019 issue of
Sky & Telescope or online at https://is.gd/
MargaretBurbidge.
■ MONICA YOUNG

J U LY 2 0 2 0 * S K Y & T E L E S C O P E

Several clubs and organizations have cancelled or postponed star parties and other
events due to the COVID-19 pandemic. In
many cases, organizers are still in the process
of making a decision on how and when to
hold a given event. We are providing an updated calendar of upcoming North American
star parties and events: https://is.gd/starparties2020. We'll update the page weekly as
the pandemic continues.
■ SABRINA GARVIN

Starlink: An Update
On March 18th, aerospace company SpaceX
sent its sixth batch of 60 Starlink satellites
into the sky, bringing the total number of Starlinks in low-Earth orbit to 360. SpaceX is thus
well on its way to having a working network
of thousands of broadband internet-providing
satellites (S&T: Mar. 2020, p. 14). On January
6th, the company launched an experiment,
dubbed DarkSat, with a dark coating to dull
reflections. But studies show that the satellite

the warp takes about 600 or 700 million years.
Yet the warp is turning considerably
faster than some theories would have us
expect. Despite some uncertainty in the
measurements, the results are certain
enough to indicate that the warp hasn't
always been there. A recent interaction
with a dwarf galaxy - already suggested
by several other lines of evidence -
could have temporarily whacked our
galaxy out of a ﬂatter state of existence.
■ MONICA YOUNG

- while notably fainter - is not faint enough
to avoid causing problems for sensitive, widefield professional telescopes, such as the
upcoming Vera C. Rubin Observatory. But a
dark coating is not the only trick up the engineers' sleeve. "SpaceX has been aggressively
pursuing multiple solutions," says Kelsie
Krafton (American Astronomical Society), who
helps coordinate talks between SpaceX and
professional astronomers. SpaceX's incremental approach to manufacturing makes it
adaptable, she adds, so potential solutions
can be continually incorporated, tested, and
improved upon. Tony Tyson (University of
California, Davis), an astronomer with the
Rubin Observatory, agrees: "SpaceX is taking
this seriously and is committed to solving the
problem," he says. Separately, on March 30th
SpaceX's only major competitor, OneWeb,
filed for Chapter 11 bankruptcy protection.
OneWeb had already launched 74 of its satellites; they, and the radio spectrum they've
claimed, will likely be sold as part of the bankruptcy proceedings.
■ MONICA YOUNG

STEFA N PAY NE-WA RDEN A A R

Margaret Burbidge,
1919-2020

An artist's concept of the warped Milky Way

https://is.gd/starparties2020 https://is.gd/starparties2020 https://www.is.gd/MargaretBurbidge https://www.is.gd/MargaretBurbidge

Sky & Telescope - July 2020

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