Sky & Telescope - USA (2019-09)

SEPTEMBER 2019 OBSERVING
Celestial Calendar by S. N. Johnson-Roehr

Cool Hunting

You’ve seen Uranus and Neptune — but have you found their moons?

The chart above spans almost

60º, or 4 hours of right ascension,

from Aquarius to Aries. On the

smaller, deeper charts on the fac-

ing page, use the ticks marking

the start of each month to deter-

mine the positions of the planets

for your observing date.

U

ranus, the faintest planet visible to the naked eye, is curling

westward through Aries this month, on its way to a late October

opposition. The icy, stinky planet (its cloud deck contains hydrogen

sulfi de) rises in mid-evening as September opens and stands well up in

the southeast near midnight at the end of the month. Glowing at mag-

nitude 5.7, Uranus is just bright enough to be viewed without optical aid

under dark skies. Binoculars easily show the planet, and a small tele-

scope at moderate magnifi cation will expose its 3.7′′ (arcseconds) disk.

In the right conditions and at higher magnifi cations, your telescope will

also reveal a hint of cyan to the orb.

If you’re not using a Go To mount, fi nding Uranus this fall will

require a bit of star-hopping — there’s no particularly bright star in

the immediate vicinity of its orbital path. Your best starting points are

Omicron (ο) Piscium, Xi (ξ) Arietis, or Xi^1 Ceti.

If you’re up for a challenge, take a run at four of Uranus’s major

moons. They’re faint, ranging from magnitude 15.0 to 13.9 from Sep-

tember 1st through opposition, so start with a 12-inch scope. Scattered

48 SEPTEMBER 2019 • SKY & TELESCOPE

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ARIES

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Path of

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Path of

Uranus

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+10°

2 h 00 m 1 h 30 m 0 h 30 m 0 h 00 m 23 h 30 m 23 h 00 m

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