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EVERYTHING YOU NEED TO KNOW ABOUT THE UNIVERSE THIS MONTH...

8 ASTRONOMY • JANUARY 2018

SNAPSHOT

The beauty

of nebulous

space

The Orion Nebula and its

neighbors reveal much

about what we see — and

don’t see — in the cosmos.

Go under a really dark sky,

and you can see a vast array of

glowing clouds of gas littering

the Milky Way Galaxy. Some

are visible with the naked eye,

others in binoculars, and most

require a telescope and a moon-

less night for visibility. The most

famous nebula of all, the Orion

Nebula, stands as a case study in

what the cosmos shows us.

Nebulae can be nebulous to

understand. Glowing clouds of

gas that are collapsing into new-

born stars, the death shrouds of

aged suns, or simply the detritus

in the ongoing cosmic recycling

program, these clouds of gas play

a major role in how galaxies

work. They are difficult to gauge;

their distances are hard to deter-

mine, unless bright stars happen

to be lodged conveniently within

them. Astronomers know the

Orion Nebula is about 1,

light-years away, but that’s an

estimate. The whole region of the

constellation Orion is swamped

in what’s known as the Orion

Molecular Cloud, a vast bubble

stretching several hundred light-

years across.

We see the brightest parts of

this complex, including the Orion

Nebula and the nebulosity sur-

rounding and backlighting the

famous dark nebula called the

Horsehead, because bright stars

energize those parts of the cloud.

But large amounts of gas, as well

as the dust that makes up dark

nebulae, mostly go unnoticed.

This area serves to remind us

that what we see in the sky is but

the tip of an iceberg. So much

more lies in the quiet darkness

that we cannot yet tease out of

space. — David J. Eicher

HOT BYTES >>

TRENDING

TO THE TOP

LIKE CLOCKWORK

An all-mechanical Venus

rover could operate

without succumbing to

instrument degradation

as quickly as previous

landers.

RESTING PLACE

Lunar probe SMART-1’s

2006 crash site was

recently discovered in

data from the Lunar

Reconnaissance Orbiter.

NONE MORE

BLACK

The exoplanet WASP-

12b’s atmosphere traps

so much light that the

planet is blisteringly hot

and appears pitch black.

The immense sea of nebulosity surrounding the southern portion of Orion appears when the gas lies close to hot stars that excite it to glow. Some dark nebulae, dust grains that

block light from behind, are also visible.

TERRY HANCOCK; TOP FROM LEFT: NASA/JPL-CALTECH; P STOOKE/B FOING ET AL. 2017/NASA/GSFC/ARIZONA STATE UNIVERSIT Y; NASA, ESA, AND G. BACON (STScI)