The Economist - USA (2021-02-13)

The Economist February 13th 2021 79

Books & arts

Scientists and aliens

Black-sky thinking

T

he objectcame hurtling in from deep
space, from the direction of Vega, a star
25 light-years away. It crossed the orbital
plane of the solar system, within which the
Earth and the other planets revolve around
the sun, on September 6th 2017. Now under
the influence of the sun’s gravitation, the
object accelerated to around 200,000mph
as it made its closest approach to the star
on September 9th. Its trajectory then took
it out of the solar system. A month after the
object had arrived, it was well on its way
back to interstellar space, moving towards
the constellation of Pegasus. 
As it catapulted past the sun and began
to head off, no one on Earth had any idea of
the object’s existence. Astronomers at the
Haleakala Observatory in Maui only dis-
covered it on October 19th; it was hidden in
the data collected by their network of tele-
scopes, as a point of light that travelled too
fast to be trapped by the sun’s gravity. They
gave it a name: ‘Oumuamua.
In the weeks after this discovery,
astronomers quickly confirmed that
‘Oumuamua (which loosely means “scout”

inHawaiian)wasthefirstinterstellarob-

ject recorded as having passed through the

solar system. Initially it was thought most

likely to have been an asteroid or a comet;

but as 2017 drew to a close, the available da-

ta continued to puzzle scientists. Their

analyses indicated that ‘Oumuamua was

small (around 400 metres long) and shiny

(perhaps ten times shinier than any aste-

roid or comet seen before). It seemed to

have an elongated, cigar-like shape, at least

five to ten times longer than it was wide.

(Later it was generally deemed to have been

flatter, like a pancake, as in the impression

in the picture.) Astronomers had never

seen anything like it. 

In addition to these physical peculiari-

ties, ‘Oumuamua  had travelled along a

path through the solar system that could

not be explained by the gravity of the sun

alone. “This, for me, was the most eye-

brow-raising bit of data we accumulated

over the roughly two weeks we were able to

observe ‘Oumuamua,” writes Avi Loeb, an

astronomer, in “Extraterrestrial”, his ac-

count of the interstellar visitation. “This

anomaly about ‘Oumuamua...would soon

lead me to form a hypothesis about the ob-

ject that put me at odds with most of the

scientific establishment.”

For, after studying the available evi-

dence, Mr Loeb concluded that the sim-

plest explanation for the exotic strange-

ness of ‘Oumuamua was that it had been

created by an intelligent civilisation be-

yond Earth. 

More things in heaven and Earth

By definition, scientists are meant to fol-

low wherever the evidence leads them. Per-

sonal biases and prejudices can cloud the

judgments of those seeking to understand

the rules of nature—but the methods of

modern scientific research, developed

over hundreds of years and keenly honed

in the past century, seek to reduce the im-

pact of subjective human factors that could

otherwise impede progress. 

Observations and data are the material

An astronomer sees evidence of life elsewhere—and takes on his fellow scientists

→Alsointhissection

81 RobertMaxwell

81 LifeanddeathinIndia

82 Johnson: Language and culture

Extraterrestrial. By Avi Loeb. Houghton

Mifflin Harcourt; 240 pages; $27. John

Murray; £20