Skip to Main Content

Christmas Sunset

Pin it

Go to Science@NASA home page

Christmas Sunset

Look west as night falls on Dec. 25th for a lovely pairing of brilliant Venus and the crescent moon.

NASA

The presents are opened, the stockings askew.
Two pounds of turkey are inside of you.

Your eyelids are drooping. The sun's going down.
Christmas is over. But wait... what's that sound?

The neighbors. They're shouting, "Look to the west!"
Outside you dash, along with the rest.

The sky is as pink as Santa Claus' nose.
And right in the middle--two UFOs!

Could it be an invasion? Some creatures from space?
Now you're awake. Your heart starts to race.

Run back to the house. Pick up the phone.
9-1-1, 9-1-1! "They're coming," you moan.

The voice on the line says, "Sir, just relax."
"There's nothing to fear. Let me give you the facts."

"Those spaceships you see aren't spaceships, no, no."
"Astronomers say it's a harmless light show."

"One's a planet called Venus, as bright as can be."
"The other's the moon. Now do you see?"

So go tell your neighbors: everything is alright."
"Merry Christmas to all. And to all a good night."

Link to story audioListen to this story via streaming audio, a downloadable file, or get help.

see captionDec. 9, 2003: It's a wonderful way to end a wonderful day.

As evening approaches on Christmas, Dec. 25th, step outside and look west toward the setting sun. Even before the sky turns completely dark you can see them: brilliant Venus and the crescent moon hanging together not far above the horizon--a beautiful sight.

Right: The Venus-moon conjunction of Dec. 25th will look much like this one, photographed by NASA scientist Vince Huegele from the banks of the Tennessee river in Alabama on Nov. 25, 2003.

Venus is so bright it's often mistaken for an airplane or a UFO. Onlookers have been known to call 911 when they see it. And when lots of people notice Venus, police phones can ring off the hook. Dec. 25th could be such a night because together the moon and Venus are unusually eye-catching.

Here's something to think about while you're gazing at Venus: Its pearly-white light looks icy and cold, but with a surface temperature of 860 F (460 C) Venus is the hottest world in the solar system. A block of lead placed on the ground there would quickly melt. Venus is so hot because it has a dense atmosphere (90 times more so than Earth's) made of 96% carbon dioxide--a planet-warming greenhouse gas. Also, Venus is thoroughly blanketed by clouds, leaden-grey and laced with sulfuric acid. These oppressive clouds, ironically, are what make the planet seem from a distance so bright and lovely. They're excellent reflectors of sunlight.

see caption

Above: Stars and planets in the western sunset sky on Dec. 25, 2003.

The crescent moon beside Venus on Dec. 25th will be equally lovely--a slender arc of bright light cradling the dark lunar disk. Look closely. Can you see a ghostly glow across the whole moon? Leonardo DaVinci first understood this phenomenon some 500 years ago. It is sunlight reflected from Earth onto the moon. Astronomers call it "Earthshine."

Side-by-side with Venus, a crescent moon with Earthshine is regarded as one of the prettiest sights in the heavens. And the ensemble is bright enough to see even from light-polluted cities.

Merry Christmas!