WWW.ASTRONOMY.COM 43LOCATING ASTEROIDS I
Vesta puts on a whale of a showALTHOUGH ASTRONOMERS DISCOVERED THREE other
asteroids before 4 Vesta, this denizen of the main belt typically
shines brighter than any other. Vesta glows with the light of a
magnitude 7.5 star this month, and you should have little trouble
finding it through a small telescope from the suburbs or with
binoculars from the country.
The asteroid rides high in January’s early evening sky, posi-
tioned against the backdrop of Cetus the Whale’s tail. This region
lies far enough from the Milky Way that you should have little
trouble picking it out of the background sky. In fact, with the
exception of four or five stars, it will be the brightest object in
your scope’s field of view. To find it, start at the 1st-magnitude
orange giant Aldebaran in Taurus, then follow the point of the
V-shaped Hyades star cluster westward (to the right) about
three binocular fields. This will get you to the magnitude 2.5 star
Alpha (α) Ceti. Shift north 5° or so from there to reach your anchor
stars, Lambda (λ) and Mu (μ) Cet. The finder chart below then lets
you zero in on Vesta’s position.
To see the asteroid change position in the course of a single
observing session, look for it on the nights of January 13, 23, or 27.
First note how it makes a crooked line or distinct triangle with a
couple of background stars, then return in a couple of hours to
find an altered pattern. On any other evening, sketch the four or
five brightest objects in your scope’s field. When you return the
next night, Vesta will be the “star” that moved.Vesta glows around magnitude 7.5 as it heads northeastward from the
watery realm of Cetus the Whale to the drier terrain of Aries the Ram.CETUSARIES
Path of VestaJan 1631
26
21161138h+NE0.5°A standout performance from the brightest asteroid (^)
January and midnight late in
the month — the sky remains
empty of planets until Mars
shows its ruddy face around
4 a.m. Within an hour or so,
you can find it low in the
southeast along with its ancient
rival, Antares. The Red Planet
brightens from magnitude 1.6
to 1.4 during January and
appears slightly fainter than
the magnitude 1.1 red super-
giant star. Mars passes 5° north
of Antares in mid-January.
As dawn starts to break
about 90 minutes before sun-
rise, the Red Planet stands 15°
above the horizon. Embedded
among the background stars
near the Scorpius-Ophiuchus
border, Mars is a sight to behold
in the predawn darkness, par-
ticularly January 20, when a
waning crescent Moon appears
above the planet and Antares.
Unfortunately, a telescope
reveals a featureless Mars with
a disk less than 5" in diameter.
Jupiter reappears in the
morning sky during January’s
second half. An hour before
sunrise on the 22nd, a slim
crescent Moon appears 7° to
Jupiter’s upper right. The pair
looks gorgeous against the twi-
light glow. The planet shines at
magnitude –1.9 and shows up
easily in the brightening sky.
Jupiter’s visibility improves
through the end of the month,
when it climbs 7° high in the
southeast 45 minutes before
the Sun rises.
Saturn is in conjunction
with the Sun on January 13,
coincidentally the same day that
the two brightest dwarf planets,
Pluto and Ceres, reach the same
milestone. The ringed planet
reemerges before dawn by the
31st, but just barely. You might
be able to catch its magnitude
0.6 glow through binoculars
just 3° high in the southeast
30 minutes before sunup. Much
better views await observers this
spring and summer.
The Moon dips into Earth’s
shadow January 10, bringing a
penumbral lunar eclipse to resi-
dents across Europe, Africa,
Asia, and Australia. During a
penumbral eclipse, the Moon
passes through our planet’s
lighter outer shadow but does
not enter the darker umbral
shadow. (If you were an astro-
naut visiting the Moon, you
would see Earth partially eclips-
ing the Sun.) The event lasts
from 17h06m to 21h14m UT
and peaks at 19h10m UT. At
maximum, 92 percent of Luna
SAGITTARIUS
OPHIUCHUS
SCORPIUS
10°
Mars Antares
Jupiter
January 31, 45 minutes before sunrise
Looking southeast
And then there were two (^)
Mars returned to view in the southeastern sky before dawn in late 2019.
Jupiter joins it in the twilight glow during the second half of January.
lies in Earth’s penumbra, and
the Moon’s southern half will
darken noticeably.
GET DAILY UPDATES ON YOUR NIGHT SKY AT
http://www.Astronomy.com/skythisweek.
Martin Ratcliffe provides
planetarium development for
Sky-Skan, Inc., from his home
in Wichita, Kansas. Alister
Ling, who lives in Edmonton,
Alberta, has watched the skies
since 1975.