This month, Venus can guide you to a naked-eye planet that
ancient astronomers inexplicably failed to see.
Ancient people didn't have TV or electric lights. So, when the sun
went down every night, they got their entertainment by watching the
sky. And it was entertaining. Without city lights to interfere, the
Milky Way was spectacular. Meteors flitted across the sky. Zodiacal
lights chased the sunset.
Of special interest were the five naked-eye planets, the ones you
could see without a telescope. (The ancients didn't have
telescopes, either.) Countless hours were spent watching Mercury,
Venus, Mars, Jupiter and Saturn, whose movements were thought to
control the affairs of men.
Would you believe, in spite of all that watching, they missed one?
There is a sixth planet you can see without a telescope, a planet
named George.
"George" is not as bright as the others, but it is there, glowing
like an aqua-blue star of 6th magnitude. It measures four times
wider than Earth, has more than 30 moons and a dozen or so thin
rings. George goes around the sun every 84 years, always spinning
on its side as if something knocked it over.
George is better known as Uranus.
English astronomer William Herschel discovered the planet in 1781
during a telescopic survey of the zodiac. He promptly named it the
Georgium Sidus (the Georgian Planet) in honor of his patron, King
George III. Later, to the everlasting delight of schoolchildren,
George was re-named Uranus, the Greek god of the sky.
Uranus had been seen many times before but mistaken for a star. The
earliest recorded sighting was in 1690 when astronomer John
Flamsteed cataloged it as 34 Tauri, the 34th star of Taurus the
Bull. We can understand the error. Uranus is so far from the sun it
looks like a star to the unaided eye. And it moves so slowly; you
have to watch for decades to realize that it is a wandereror, in
ancient Greek, a planētēs.
In modern times, Uranus has become all but impossible to see. The
planet is naturally faint, and urban lights wipe it out completely.
No one notices when Uranus soars overhead.
Nevertheless, you can see Uranus this month. Another planet will
guide you to it.
On April 17th, 18th and 19th, Venus and Uranus are going to have a
close encounter in the dawn sky. Simply look east before sunrise.
As a guidepost, Venus can't be beat. It is so bright, people often
think it's a landing airplane. Simply scan Venus with a pair of
binoculars (or a small telescope) and you'll see Uranus right
beside it. If the sky is very dark, you may be able to lift your
eyes from the optics and see Uranus directly.
On April 17th the pair will be separated by about one degree, the
width of your pinky finger held at arm's length. On the 18th
they'll be even closer together, 0.3 degrees. On the 19th the
distance increases again to one degree.
The view through a backyard telescope should be splendid.
Diamond-bright Venus has phases, and at the moment it resembles a
tiny half-moon. Uranus, meanwhile, is a little blue-green disk,
clearly a planet.
Set your alarm and see what the ancients missed.
Sky Map:
Note: Singaporeans will have hard time viewing it, due to light
pollution. We have too many lightings.
