Evening
skywatchers are still enjoying the sight of at least three of the five bright
naked-eye planets: Venus and Saturn in the western sky and Jupiter, low in the
southeast. And if you really stay up late say after 1:30 a.m. local daylight
time you can add a fourth planet, Mars, emerging from above the eastern
horizon and which will become increasingly prominent during the summer and fall
as it slowly approaches the Earth.
But this weekend really belongs to Venus and Saturn, both easily visible in the western sky just as darkness falls.
The two
planets will put on a show on both Saturday and Sunday evenings when they will
appear within 0.8-degrees of each other.
The actual
moment of closest approach will occur at 09:33 Universal Time on Sunday, when
they will appear to close to within 0.66-degrees of each other. How close is
that? The apparent width of the Moon is equal to one-half degree, and the width
of your fist held at arm's length is roughly equal to 10 degrees. Unfortunately,
the two planets will be below the horizon at that hour for North America, while
Europe will be in daylight. It will be around sundown for Japan and Australia, however, where a good view of the closest approach between the two planets can
be seen.
The two
planets will then slowly pull away from each other during the rest of July.
On Friday
evening, June 29, dazzling Venus will
be below and to Saturn's
right. Saturday evening, Venus will appear directly underneath Saturn. Come
Sunday evening (July 1), Venus will have shifted to the lower left of Saturn.
By
Tuesday, July 3rd, the gap between the two planets will have widened
noticeably, but now they'll be side-by-side, with Venus on the left, Saturn on
the right.
Specific
observing details for both planets for the coming weeks:
Venus
Venus has been a prominent evening object since January,
will finally relinquish the title of "Evening Star" by the start of
August, so July will be your last full month to enjoy it during convenient
evening hours before it makes the transition to the morning sky.
On the 8th, Venus attains its greatest brilliancy and blazes
at an eye-popping magnitude of -4.5. But compared to just a week earlier it
will be noticeably lower in the sky at sundown and setting just 2 hours later.
On the evening of the 12th, Venus will pass less than 2-degrees below Regulus,
the brightest star in the constellation Leo; you may, however, need binoculars
to see the star.
By the end of July, Venus will be setting only 45 minutes
after sunset; you'll need a clear and unobstructed horizon to spot it. A few
more days into August and it will finally be gone from our evening sky. It will
sweep between Earth and the Sun (inferior conjunction) on Aug. 18, then, just a
week later it will emerge into view as a morning object, rising in the east
about 45 minutes before sunrise.
By the end of August, Venus will be rising around 5 a.m.
local daylight time, ultimately becoming a brilliant predawn fixture in the
eastern sky for the balance of the year. If you have a telescope or even
7-power binoculars (held steadily or mounted on a tripod) you'll see Venus will
appear as a beautiful crescent phase all during July and again late in August.
Saturn
Saturn begins July hovering just above and to the right of
dazzling Venus, and in fact, follows Venus' plunge into the sunset fires as the
month progresses.
Saturn is shining at a very respectable magnitude of +0.6,
but unfortunately this pales to the brilliance of Venus. Indeed, Saturn only
appears one-hundredth as bright! Currently located in the constellation of Leo,
Saturn's famous ring system is now tipped about 14-degrees toward Earth and
still provides a spectacular view even in small telescopes.
Made up by billions of ice and rock particles of all sizes
from small debris to boulders as big as houses these rings orbit Saturn at
varying speeds. There are hundreds of these rings, believed to be pieces of
shattered comets, asteroids or moons that broke apart before they reached the
planet. The rings are so big that they would fill most of the distance between
Earth and the Moon.
Speaking of the Moon, a lovely crescent will appear to hover
just below and to the left of Saturn on July 16. On the next evening it will
have moved well off to the east, past Venus.
One final point: if you compare Venus and Saturn with a
telescope, you'll be struck by how much more dazzling Venus appears in luster
compared to the mellow yellow of Saturn.