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Nov.
24, 2008: This story ends with the best sky show
of the year--a spectacular three-way conjunction of Venus,
Jupiter and the crescent Moon.
It
begins tonight with a sunset stroll.
At
the end of the day, when the horizon is turning red and the
zenith is cobalt-blue, step outside and look southwest. You'll
see Venus and Jupiter beaming side-by-side through the twilight.
Glittering Venus is absolutely brilliant and Jupiter is nearly
as bright as Venus. Together, they're dynamite:
Above:
Venus and Jupiter converging over Hawaii on Nov. 19, 2008.
Photo credit and copyright: Stephen O'Meara. [Larger
image]
Add
another stick of TNT and voila!—it's tomorrow. Go outside
at the same time and look again. You’ll be amazed at how much
the Venus-Jupiter gap has closed. The two planets are converging,
not in the slow motion typical of heavenly phenomena, but
in a headlong rush—almost a full degree (two full Moon widths)
per night. As the gap shrinks, the beauty increases.
On
Nov. 29th (sky map)
the two planets will be less than 3 degrees apart and you'll
think to yourself "surely it can't get any better than
this."
And
then it will. On Nov. 30th (sky
map) a slender 10% crescent Moon leaps up from the horizon
to join the show. The delicate crescent hovering just below
Venus-Jupiter will have cameras clicking around the world.
Dec.
1st (sky map)
is the best night of all. The now-15% crescent Moon moves
in closer to form an isosceles triangle with Venus and Jupiter
as opposing vertices. The three brightest objects in the night
sky will be gathered so tightly together, you can hide them
all behind your thumb held at arm's length.
The
celestial triangle will be visible from all parts of the world,
even from light-polluted cities. People in New York and Hong
Kong will see it just as clearly as astronomers watching from
remote mountaintops. Only cloudy weather or a midnight sun
(sorry Antarctica!) can spoil the show.
 Although
you can see the triangle with naked eyes--indeed, you can't
miss it—a small telescope will make the evening even more
enjoyable. In one quick triangular sweep, you can see the
moons and cloud-belts of Jupiter, the gibbous phase of Venus
(69% full), and craters and mountains on the Moon. It's a
Grand Tour you won't soon forget.
Right:
A sky map of the triple conjunction on Dec. 1, 2008. More
maps: Nov. 24,
25, 26,
27, 28,
29, 30,
Dec. 1 2008.
Finally,
look up from the eyepiece and run your eyes across the Moon.
Do you see a ghostly image of the full Moon inside the bright
horns of the crescent? That's called "Earthshine"
or sometimes "the da Vinci glow" because Leonardo
da Vinci was the first person to explain it: Sunlight hits
Earth and ricochets to the Moon, casting a sheen of light
across the dark lunar terrain.
By
itself, a crescent Moon with Earthshine is one of the loveliest
sights in the heavens. Add Venus and Jupiter and … well ...
it's time to stop reading and go mark your calendar:
Dec.
1st @ sunset: Sky show of the year!
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Author: Dr.
Tony Phillips | Credit: Science@NASA
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