A Schedule of Events
through superior conjunction – passing “behind” the Sun from Earth’s
point of view - on August 8th, and slowly begins to climb
into the evening sky. You’re unlikely to see it at all, however,
unless you have a clear view low to the western horizon shortly
after sunset. For Northern Hemisphere observers, this is the worst
evening appearance of Mercury of the year.
the month in Virgo but crosses the border into Libra on the 10th.
The planet starts out the month at magnitude +0.4, but dims to +0.6
by the 31st. Its view through a telescope is
disappointing, as it shrinks from 8 arc-seconds to 7” wide during
Not so its neighbor,
In fact, the two approach each other quite closely this month. Mars
and Saturn lie within 4° of each other from the 20th to
the 29th. Their closest approach occurs on the 27th,
when Mars lies just 3.6° from Saturn. By then both will be of
similar brightness – magnitude +0.6. Brightness difference aside,
can you tell them apart by their color? Mars, of course, is reddish;
Saturn should appear yellow-white. Certainly, though, as seen
through a telescope, they could not be more different. Saturn’s disk
is about 16” in diameter, with its magnificent ring system
stretching 36” across. And, in contrast to the two moons of Mars –
which are tiny and beyond the reach of most amateur telescopes –
Saturn boasts a full retinue of satellites, up to half a dozen of
which may be visible in larger scopes.
reaches opposition on August 29th, which means it’s at
its closest, brightest, and largest of this entire year. For this
remote planet, though, that is not saying much. The planet is almost
2.7 billion miles from us, shines at a feeble magnitude 7.8, and
displays a disk no more than 2.4” across in a telescope. In smaller
scopes, it may be difficult to distinguish from a star.
Neptune’s sister “ice giant”,
Uranus, does slightly better. It rises about an hour and a
half after Neptune, in the constellation Pisces. Even though it is
not yet at opposition and therefore nearest to Earth, it is “only”
1.8 billion miles away. It is therefore brighter; at magnitude 5.8,
it may even be within naked-eye range from dark sky sites. In a
telescope, it displays a clear greyish-green disk about 3.6” wide.
Perhaps the most remarkable of planetary
sights this month occurs in the morning sky, low in the east before
dawn: a conjunction between Venus and
During the first half of August, Venus rises first, about an hour
and a half before the Sun. Jupiter follows about a half hour later.
But day by day, they get closer. On the morning of the 18th,
only 15 arc-minutes – or about half the width of the Full Moon –
separate them. Venus, at magnitude -3.8 – will be the brighter of
the two; Jupiter will muster a magnitude – 1.8. Both should be
visible in the same field of view of the average telescope. Venus
will display an almost full disk about 10” across, while Jupiter
will be 32” across. However, don’t expect to see much detail in any
case; the two will be quite low in the predawn sky, and morning
twilight will be approaching. Following the conjunction, Venus and
Jupiter “pass” each other in the sky, and for the rest of the month,
it will be Jupiter that rises first.
At midmonth, the dwarf planet/asteroid
1 Ceres and the asteroid
4 Vesta are about
3° apart, in the eastern part of Virgo.
Pluto is just past opposition, so
this is a good time to try to search for it. You’ll need a large
telescope and detailed star charts. It shines no brighter than
magnitude 14.1, and is in rich star fields in Sagittarius.
A Super Moon !
The moon takes 29.5 days to return to
the same point on the celestial sphere every month – its
so-called syndonic period. That means there are about 12 or 13
Full Moons in a year. The Moon’s orbit around the Earth is an
ellipse, and the Full Moons don’t necessarily occur during
perigee (when the Moon is closest to Earth). Inevitably,
however, one of these Full Moons will occur when the Moon is
nearer to perigee than at other times.
One such case occurs this month; the
Full Moon of August 10 will be the closest of the year. How
Astronomers typically measure the
distance between bodies as the distance between their centers
(rather than their surfaces). At the Full Moon on August 10th,
the centers of the Earth and Moon will be 221,765 miles apart.
(The surfaces of the two bodies will be 216,068 miles apart.)
How does this compare to the furthest
Full Moon of 2014? The most distant Full Moon (when the Full
Moon was near apogee – the farthest distance from Earth)
occurred on January 15 of this year, when the centers of the
bodies were 257,607 miles apart.
So this month’s Full Moon will be
35,842 miles closer than that of January. The difference in
distance is 12.2%. If you saw both objects side by side, you
could tell the difference. Lacking that, the two Moons will
appear essentially the same in size. And, since the area of the
Moon is a function of its diameter, the August Moon will be 26%
brighter than that of January. Again, if you could see them side
by side, you’d notice the difference, but when humans go on
memory, the results are often unreliable.
So, why is this August Full Moon
called a “Super Moon”? The term seems to hark back to a
reference in an astrology (yes – astrology!) article back
in 1979. And given its pedigree, it has now become a loaded
term, often accompanied by predictions of monster tides and
assorted world disasters. The best thing we knowledgeable
professional and amateur astronomers can do is to use it as a
“teachable moment” to educate the public about what is really
The approximate size of
the Full Moon at apogee and at perigee (a “Super Moon”)
August 11, 2014 Star Chart
10:00 PM EST
Looking at Zenith, South at Bottom
From areas with dark skies, one can see the Milky Way
passing across the entire sky this month. Start by looking directly
overhead, toward Cygnus and Lyra. Then trace the line of the subtle
Milky Way all the way to Scorpius and Sagittarius. What we’re seeing
is the plane of the galaxy in which we are embedded. You don’t
need a telescope to explore this area; a good pair of binoculars
will do. You will basically be seeing what Galileo first saw when he
first turned a telescope at the Milky Way. The diffuse glow is in
fact composed of uncounted thousands of individual stars. The more
you look, the more you will see!