Astronomy - USA (2020-06)

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farther from the core you look,

the more individual stars you’ll

be able to see.

We end our springtime

hunt for globulars with the

brightest of the season — and,

indeed, the brightest in the

Northern Hemisphere sky: M5

in Serpens Caput. This great

object glows at magnitude 5.7

and measures 17.4' across.

To find it, look 12° north

of Zubeneschamali (Beta

Librae). Sharp-eyed observers

can spot M5 from a dark site

without optical aid. If your

eyes are up to the task, you’ll

first spot the 5th-magnitude

star, 5 Serpentis, 22' southeast

of M5. The star is twice as

bright as the cluster.

M5 explodes with detail

through any size telescope.

That said, a 4-inch scope will

reveal just a few dozen stars,

while an 11-inch will expose

more than 100. At a magnifica-

tion of 150x or more, you’ll see

that M5 has a grainy structure

and that its core is condensed,

making up about 25 percent of

the cluster’s diameter. Make

sure to also look for the many

streamers of stars emanating

from its core.

Summer

More globulars populate the

summer sky than during any

other season. Our starting

point will be M80 in Scorpius,

one of the easiest globs to

find. It lies midway between

Antares (Alpha Scorpii) and

Graffias (Beta Sco).

Although you’ll spot this

magnitude 7.3 object through

any scope, instruments with

apertures less than 8 inches

won’t reveal much. M80, which

spans 8.9', is quite condensed.

One particular star you’ll

surely spot is magnitude 8.5

SAO 184288, a foreground star

that lies at the northeastern

edge of the cluster.

Two more globs lie in the

northern part of Scorpius. The

first is M4. To find it, just cen-

ter Antares in your eyepiece

and M4 will be to its west. This

terrific object glows at magni-

tude 5.4 and, at 26.3' wide, has

a diameter 85 percent that of

the Full Moon.

A 6-inch telescope will let

you see 20 or so stars scattered

loosely across M4’s face. Notice

the chain of stars running

north to south through the

cluster’s center. Through a

12-inch or larger scope

cranked up to magnifications

of 200x or more, you’ll see

several hundred stars, which

More globulars

populate the

summer sky

than during

any other

season.

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