Planets to form ‘Christmas Star’
Look to the sky tonight
lOWOll » UMass Lowell astronomer Silas Laycock says anyone planning to give a telescope as a gift this holiday season might want to surprise the recipient with the present a bit early.
Tonight, stargazers will have the opportunity to see a celestial event grace the night sky that has not been visible to the naked eye for nearly 800 years.
Laycock has been tracking Jupiter and Saturn over the past few weeks as the solar system’s largest planets draw closer together in the western sky.
He points out todayis the date when the two planets will align in a position scientists call the “Great Conjunction” — the point at which the two planets are closest together in the night sky as seen from Earth.
“The planets will be separated by such a small amount of sky, that you will only be able to see one point of light,” Laycock said.
The alignment will create what will appear as one bright spot, low in the night sky. The phenomenon has earned the nickname the “Christmas Star,” used by many amateur astronomers, according to Laycock.
For Laycock — who, according to his UMass Lowell biography, has an expertise in pulsars, black holes and binary stars — this is an out-of-this-world event.
“It’s a great way to see the workings of the solar system,” he said.
The distances are astronomical, with Jupiter roughly 539 million miles from Earth on Dec. 21, and Saturn 995 million miles away. Though the two planets will be the closest together on this date, they will still be extremely far apart. According to Laycock’s calculations, the planets will be roughly 450 million miles from each other on Dec. 21.
The last time Jupiter and Saturn were this close together was in 1623, according to Laycock. However, due to the conjunction’s proximity to the Sun, it would not have been visible from Earth. You would
have to go back to 1226 when this celestial event was last visible to the eyes of humankind.
To put it in perspective, at that time, conqueror Genghis Khan still ruled the Mongol Empire and there were still five and a half centuries to go until the Declaration of Independence.
Those who want to view the once-in-a-lifetime event should head outside right after sunset, with sunset on Dec. 21 at around 4:15 p.m. As it gets dark, the two planets will become visible just above the western horizon.
Jupiter and Saturn are just 20 degrees above the horizon, or about the width of your hand at arm’s length, Laycock said. They will dip below sight by 7 p.m.
Laycock encouraged those interested to scout out a viewing spot in advance.
“Don’t wait until the 21st,” he added. “They’re getting closer and closer each day.”
For more tips on viewing the Christmas Star, visit the UMass Lowell Observatory Facebook page.