CAMBRIDGE, Mass. – Comet Hale-Bopp dazzled us for weeks. The Perseid meteor shower thrilled us for one night. But the world hasn’t seen anything like the planetary traffic jam that’s going to occur the last week of April and the first two weeks in May.
Inching across the sky like bumper-to-bumper commuters on their way to work, a rare planetary alignment will allow sky observers to see every planet in our solar system in a single evening.
“There will be other opportunities in the future to see the planets in different configurations,” said Philip Sadler, of the Harvard-Smithsonian Center for Astrophysics, “but it won’t be anything like this for at least another 70 years. This is truly a once-in-a-lifetime experience.”
Look up! Even more amazing, two special events will occur during this planetary lineup. On May 10, the planets Mars and Venus will appear to pass so close to one another that, to the naked eye, they will seem to become one bright heavenly object.
Something even more spectacular will happen May 5. The bright planets Mars, Saturn and Venus will group together to form a perfect equilateral triangle in the western sky. This configuration will be visible almost everywhere on Earth.
Points to Bethlehem. In the Middle East, this pyramid-shaped specter will hang directly above Bethlehem.
Oddly enough, more than 2,000 years ago, this same grouping of planets may have caught the attention of the Biblical Magi.
On April 1, 2 B.C., the planets Mars, Saturn and Venus came together to form a perfect equilateral triangle over the city of Bethlehem. Now, in the 21st century, amid the turmoil taking place in the Middle East, the ancient Roman gods of love, war and agriculture/wisdom, are coming together to look down upon this war-ravaged landscape once again.
Nine worlds in one night. In late April and early May, when the planets line up, they will not be arranged behind one another or the Sun. Instead, they will present a line across the sky from horizon to near zenith.
For a period of a little more than three weeks, anyone looking west at sunset will be able to see the planets Mercury, Venus, Mars, Saturn and Jupiter. A few hours later at 4 a.m., armed with a large-size amateur telescope, they can continue their grand tour by observing Uranus, Neptune, Pluto, a few wandering asteroids and maybe even Comet Ikeya-Zhang in the east.
Finally, by quickly glancing down at the ground, they will have completed their grand tour of the solar system.
“Seeing nine worlds in just one night is something few astronomers can say they’ve accomplished,” said Sadler. ” I can’t wait to do it myself!”
Insight into past. Looking at the planets spread out across the sky during this alignment also demonstrates how the solar system formed 4 billion years ago.
“Our solar system condensed out of a nebular dust cloud that flattened down into a giant disk that resembled a big pizza pan,” said astrophysicist David Wilner. “Utilizing instruments like the Hubble Space Telescope and data from the Infrared Astronomical Satellite, we are now witnessing the formation of new solar systems spread out into flattened discs of gas and dust. We are even detecting large lumps of material in the dust disks that may be the signatures of planets in formation.
“Astronomers are now assembling snapshots of our own past frozen in time billions of years ago.”
Ancient dust ring. This pathway of planets, or the ecliptic as astronomers call it, is what remains after our dust cloud coalesced into planets.
Tracing the path of this ancient dust ring across the sky is easy.
Stand sideways facing south with your right hand extended and pointing to where the Sun recently set along the western horizon.
Now, extend your arm up to point at the Moon or a bright planet overhead. Connecting these two points together, continue to sweep your arm in an arc until it reaches the opposite horizon. Bingo! You have just traced out the ecliptic.
All the planets will be found along this line and nowhere else. And this is where the traffic jam will occur.
Highway of the gods. “Coincidentally,” said Sadler,” have you ever wondered why the 12 signs of the zodiac were chosen? Why someone you know wasn’t born under the sign of Hercules or Orion?”
To the Greeks and Romans, the ecliptic was the Highway of the Gods or the path the planets and Moon moved across at night and the Sun traveled during the daytime. Located directly behind this highway were the 12 special constellations the gods passed by as they moved across the sky. They constituted the signs of the zodiac.
This was the basis for astrology – religious beliefs and basic sky observations mixed together.
Star of Bethlehem. Today, it is widely held by many historians and planetarium directors that a conjunction of the planets, similar to the one on May 5, accounts for the Star of Bethlehem that sent the Magi on their way to seek the Christ child. Certainly the timing was right. An almost identical triangular alignment of Saturn, Mars and Venus did take place on April 1, 2 B.C. And the planets Jupiter, Saturn and Mars also formed a triangular conjunction in 6 B.C., in the constellation Pisces, the sign of the Christians.
However, renowned astronomical historian Owen Gingerich of the Harvard-Smithsonian Center disagrees.
“The very, very short duration of a grouping of planets was not the Star of Bethlehem,” he said. “A conjugation like this would have meant nothing to the Magi. It was not part of their astrological tradition.
“It really wasn’t until Kepler became fascinated with the harmony of the planets in the 16th century that the idea of a planetary conjunction came about to try to attach a scientific explanation to this event. In fact, Kepler even went so far as to add an imaginary supernova to the conjunction of planets in 6 B.C. to try to make it even more spectacular to catch the Magi’s attention.”
