Science News - USA (2021-03-13)

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JANUARY 30, 2021

A smash hit

In “A complete collection of cosmic smash-

ups” (SN: 1/30/21, p. 30), Emily Conover

and Nadieh Bremer visualized every gravi-

tational wave event spotted so far.

Freelance data visualization designer

Nadieh Bremer “reduced an excruciat-

ingly complex subject, gravitational

waves produced by cosmic collisions,

into a very interesting graphic. Emily

Conover made it understandable,”

reader Richard Polangin wrote.

“Bravo to your very gifted staff!”

Reader DaveProffitt noticed the

colliding black holes were quite massive.

“Why no detections in the [mass] range

of commonly known black holes?”

It’s easier for the LIGO and Virgo

observatories to spot more massive

mergers because the gravitational waves

are larger. “So, it’s true that there are a

lot of detected events that were quite

massive. However, there are a handful of

detected events that involve quite small

black holes ,” Conover says. One detec-

tion, represented in the illustration

by the small circle at about 1.6 b illion

years, resulted from the merger of a

black hole with about 8.8 solar masses

and a black hole with about five solar

masses. “Three solar masses is the lower

limit for what can be confidently called

a black hole,” she says. “You can’t get

smaller than that without it being dif-

ficult to d etermine whether it’s a black

hole or a neutron star.”

Left out

Scientists are getting inventive with ways

to touch down on Earth’s neighbors, Lisa

Grossman reported in “How to safely land

on Venus or Europa” (SN: 1/30/21, p. 12).

Reader Michael Stebel was disap-

pointed that the story did not mention

the Huygens probe, which landed on

Saturn’s moon Titan in 2005. “Although

[the probe] sent back data and images

for less than six hours , it was an incred-

ible achievement ... especially notable

when one considers the distance

involved, the extreme cold and the thick

hazy atmosphere of Titan,” he wrote.

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