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See Moon, Jupiter and Mars before sunup |
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February 6, 2018 |
By Bruce McClure
EarthSky.org
On the mornings of February 7 to 9, early risers
can watch the moon as it moves in its orbit past
the planets Jupiter and Mars in Earth’s predawn
sky.
Look generally southward before sunup from the
Northern Hemisphere and northward, or high
overhead, from the Southern Hemisphere.
Mars rises later at night, closer to the time of
sunup, but night owls will find Jupiter climbing
above the eastern horizon in the wee hours after
midnight around now.
If you’re out very late with someone special,
you’ll enjoy pointing out Jupiter, which – since
Venus is in the sun’s glare – is the brightest
starlike object in the night sky this month.
After rising in the east, Jupiter climbs upward
until soaring highest up for the night at
roughly 6 a.m. local time. That’s the time on
your clock as seen from around the world.
Around now, both Jupiter and Mars are well
placed for viewing before dawn’s light washes
the sky.
Click here for recommended almanacs; they
can help you find the exact rising times for the
moon and planets into your sky.
The moon is at or near its last quarter phase
around February 7.
This month, Jupiter is shining in front of the
constellation Libra the Scales. You might – or
might not – see Libra’s two brightest stars,
Zubenelgenubi and Zubeneschamali, in the glare
of the moon. But once the moon moves by Jupiter
after a few more days, you can use Jupiter to
find Libra’s two modestly-bright third-magnitude
stars for months to come.
Jupiter and the constellation Libra’s stars rise
about four minutes earlier daily and one-half
hour earlier weekly.
So in another few months, you can look forward
to seeing Jupiter and the constellation Libra in
the evening sky well before your bedtime.
Jupiter’s opposition – when Earth will pass
between this outer planet and the sun, marking
the middle of the best time of year to see it –
will come on May 9.
And Mars? It’s the planet to watch in 2018, and
it’s shining at the border of the constellations
Scorpius and Ophiuchus in early February.
Contrast its brightness with the red star
Antares – brightest star in the constellation
Scorpius the Scorpion – in early February. Then
look again in late February. Mars is brightening
fast now and might outshine Antares, by a hair,
by late February.
In 2003, Mars was closer and brighter in our sky
than in nearly 60,000 years. Around its late
July 2018 opposition, Mars will be at its
brightest since then!
Let the moon guide you to Mars on these February
mornings so that you can start watching Mars
now.
Night by night, as we stand on Earth’s surface
watching the moon, we can see it shift its
position in front of the fixed stars and
wandering planets. This motion is due to the
moon’s actual motion in orbit around Earth.
The moon takes about a month (one moonth) to
orbit the Earth. Although the moon rises in the
east and sets in the west each day (due to
Earth’s spin), it’s also moving eastward through
the constellations of the zodiac due to its
orbital motion.
The moon’s orbital motion can be detected in the
course of a single night, but you have to watch
the moon closely, with respect to stars in its
vicinity, over several hours.
The moon’s eastward, orbital motion is easiest
to notice from one day (or night) to the next.
The moon moves – with respect to the fixed stars
– by about 12 to 13 degrees each day.
The planet Saturn is also up before dawn. You’ll
see the moon closing in on Saturn beginning
around February 9 or 10, and closest to Saturn
on February 11. |
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