Kenneth L. Franklin, the
former Chairman and Chief Astronomer at New York's Hayden Planetarium, would
often make reference to our "dynamic and ever-changing sky." His description
certainly fits our current morning sky, as we now have a celestial summit meeting
in the eastern twilight.
For the past several months,
dazzling Venus has been prominent in the mornings. A few weeks ago, brilliant
Jupiter also began to emerge from out of the dawn twilight.
These two planets had a
spectacular rendezvous on Nov. 4. Now, as they begin to slowly separate, a rather
dim Mars, which from our point of view has been on sabbatical since the start
of the summer, hidden within the glare of the Sun, began to reappear during
this past week, very low near the east-southeast horizon. And not far from Mars,
glows the bluish-white, first-magnitude star, Spica.
Lastly, there's the Moon.
At last quarter (half) phase on Nov. 5, it stands alone, high toward the South
at sunrise.
But with each passing morning,
as it wanes to a slender crescent, the Moon shifts toward the East, ultimately
into the same region of the sky as our three planets. During this week, each
dawn will offer a different perspective of this unusual gathering of the Moon,
three planets and a bright star.
Early on Tuesday morning,
Nov. 9, the show will reach its peak, when about 45 minutes before sunrise,
Venus, Jupiter and the Moon - the three brightest objects of the night sky -
form a stretched-out triangle. The Moon will appear closely above Jupiter. Meanwhile,
Spica and Mars will lie well below the Moon, appearing just above the horizon.
Like a painting, this celestial
tableau might at first glance may appear rather flat and one-dimensional. But
by gazing at this scene long enough, our minds can perhaps picture these objects
strung out across the solar system, along our line of sight as they really are.
Beyond our Moon (figuratively
a stone's throw away at 236,000 miles away) we first reach Venus, about 500
times farther out, or 120 million miles from Earth. The lesser gem flanking
Venus - Jupiter, largest of all the planets - is nearly 5 times more distant
than Venus and 576 million miles from us.
Far below and much closer
to the east-southeast horizon is Mars, currently almost twice as distant from
the Earth as Venus at 235 million miles. Indescribably more remote is Spica
at 262 light-years way. Consider this: the light we see this month left the
star more than three decades before the United States was founded.
Venus is brilliant as always,
shines about eight times brighter than Jupiter.
Venus rises an hour or so
before dawn breaks, and about 50 minutes before sunrise during most of November,
it blazes at least 20 degrees up in the east-southeast. Your fist on an outstretched
arm covers roughly 10 degrees of sky.
Venus is now several months
past greatest elongation, the location farthest from the Sun as seen from Earth,
and is retreating around the far side of the Sun, so a telescope will show it
gibbous and small. Yes, Venus goes through phases, somewhat like our Moon.
Although by far the brightest
planet once it gets clear of the horizon hazes, Venus is not as showy as it
was late last summer when it appeared higher and brighter. Naked-eye observers
will enjoy watching Venus go by Spica during midmonth; passing 4º north of that
star on Nov. 16.
Mars moves from the constellation
Virgo into Libra by Nov. 22. It rises out of the east-southeast just after 5
a.m. local time on Nov. 1 and only about 15 minutes earlier by the end of the
month. At magnitude +1.7, Mars is still a relatively inconspicuous object. Larger
numbers on this scale denote dimmer objects, with the brightest
objects achieving negative magnitudes.
The delicately thin crescent
Moon will hover well above and to the right of Mars on the morning of Nov. 10.
Spica will lie below the Moon. On the following morning, the Moon will appear
as a razor-thin arc of light, just 3% illuminated, when it will be positioned
well below and slightly to the left of Mars.
Jupiter in Virgo, rises
in the east around 3:45 a.m. local time at the beginning of November; 2:20 a.m.
by month's end. At dawn Jupiter is well up in the southeast.
As noted above, Venus, Jupiter
and the Moon will make for a striking predawn sight on Nov. 9. Even more interesting:
After sunrise that day the Moon will actually occult (hide) Jupiter as seen
from much of central and eastern Canada, as well as parts of the Great Lakes
and the Northeast United States.
Next month, the Moon will
again pass in front of Jupiter, but before sunrise (in a dark sky) and visible
over much of eastern and central North America; a truly spectacular sight!
Basic Sky Guides
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Map
the Planets
from Home!
Starry
Night software brings the universe to your desktop. Map the sky from
your location, or just sit back and let the cosmos come to you.
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MORE!
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Joe Rao
serves as an instructor and guest lecturer at New York's Hayden Planetarium.
He writes about astronomy for The New York Times and other publications, and
he is also an on-camera meteorologist for News
12 Westchester, New York.
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DEFINITIONS
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Degrees
measure apparent sizes of objects or distances in the sky, as seen from
our vantage point. The Moon is one-half degree in width. The width of
your fist held at arm's length is about 10 degrees.
1 AU, or
astronomical unit, is the distance from the Sun to Earth, or about 93
million miles.
Magnitude
is the standard by which astronomers measure the apparent brightness
of objects that appear in the sky. The lower the number, the brighter
the object. The brightest stars in the sky are categorized as zero or
first magnitude. Negative magnitudes are reserved for the most brilliant
objects: the brightest star is Sirius (-1.4); the full Moon is -12.7;
the Sun is -26.7. The faintest stars visible under dark skies are around
+6.
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