The world’s best-selling astronomy magazine

QG

QUANTUM

GRAVITY

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

WWW.ASTRONOMY.COM 7

SNAPSHOT

Don’t

let the

Horsehead

get ya

One of the sky‘s

most storied objects

is notoriously difficult

to observe.

In this day and age, when relative-

ly few people have truly dark skies

overhead, some celebrated sky

objects are quite hard to see. Such

is the case with one of the most

famous dark nebulae in the sky,

the Horsehead Nebula in Orion.

Cataloged as the 33rd object in

Edward E. Barnard’s list of dark

nebulae, the object has been cel-

ebrated for more than a century

for its shape. The cloud of tiny

particles, dust grains about the

size of those in cigarette smoke,

takes on the shape of a horse’s

head in profile, backlit by a thin

streamer of bright nebulosity

known as IC 433. This whole

scene is tucked just under the

easternmost star in Orion’s Belt.

It’s relatively easy to photo-

graph the Horsehead Nebula

under a dark sky, provided one

uses the right equipment. But

incredibly detailed images of the

area like the one presented here,

by noted astroimager Adam

Block, are not easy to create.

And seeing the Horsehead in

a telescopic eyepiece is another

thing altogether. This absolutely

requires a dark sky, with out-

standing transparency and seeing,

and a night with no Moon

hanging in the sky. Moreover,

most observers report needing a

telescope 12 inches or larger to

have an effective shot at the

Horsehead Nebula (although

credible reports from experienced

observers have been made with

5- or 6-inch refractors).

Using a good nebula filter will

also help to bring out IC 433 and

thereby backlight the dark

Horsehead. Persistence is critical:

Realize that the nebula is smaller

than most expect and requires

just the right night. Don’t give up

trying. Don’t let the Horsehead

get ya. — David J. Eicher

HOT BYTES >>

TRENDING

TO THE TOP

NEW DAWN

NASA’s Dawn mission

will stay at the

dwarf planet Ceres

permanently, in a

new orbit.

DIM LIGHT

Tycho’s famous

supernova progenitor

was a cool white

dwarf, not a huge,

hot, luminous star.

IN COLOR

Mars Odyssey measured

Phobos’ surface

temperature to map

its composition for

potential manned

missions.

The Horsehead

Nebula offers a

significant

challenge to

visual observers

of the deep sky.

ADAM BLOCK; TOP FROM LEFT: NASA/JPL-CALTECH/UCLA/MPS/DLR/IDA/JUSTIN COWART; NASA/CXC/RUTGERS/DSS/ K. ERIKSEN ET AL.; NASA/JPL-CALTECH/ASU/SSI