I can’t believe we’re still performing this archaic ritual, but on Sunday, March 10, we’ll again set our clocks one hour ahead to daylight saving time and “spring forward.”
Well, most of us will.
Hawai‘i, Arizona (except the Navajo Nation), a few U.S. territories and some other countries are sensible enough not to participate in the madness.
When planning to observe future celestial events, knowing the correct time is essential. This depends not only on the time zone in which one lives but also, in many cases, whether the clock reads standard or daylight saving time. It can be quite confusing.
Thankfully, this week’s sky events depend not on the exact times, just on the dates, because the waxing crescent moon in its orbit around the Earth will pass by two of the most beautiful objects in the heavens.
You’ll most likely spot the delicate crescent moon low in the western sky at dusk early this week.
As darkness begins to fall, look carefully at the moon, and you’ll see not only its bright sunlit crescent, but also the ghostly image of its full disk.
This phenomenon was first explained by the 15th century Italian artist and inventor Leonardo da Vinci.
He recognized that whenever we see the moon as a crescent in our sky, a hypothetical sky watcher on the moon would see a nearly full Earth in the lunar sky.
And just as a bright moon illuminates the dark landscape on Earth, a brilliant Earth illuminates the dark surface of the moon even more brightly.
On Wednesday night, March 13, look for the moon to appear next to the planet Jupiter high in the western sky at dusk.
Even 491 million miles away, Jupiter appears dazzling because it’s so immense (11 times the diameter of the Earth) and reflective (more than half of all sunlight that falls on its cloud tops bounces back into space).
While you’re out enjoying the crescent moon and Jupiter, look above this pair for the tiny shimmering star cluster known as the Seven Sisters, or Pleiades.
This is where the moon will appear on the following night, Thursday, March 14, when it will offer us a great opportunity to break out the binoculars.
On that night, you’ll see both the moon and the Pleiades in the same binocular field of view.
If you’ve never viewed the Pleiades this way, however, it won’t be the same view as you’ll get on a moonless night. Even in its crescent phase, the moon can be quite the showoff and will wash out all but the brightest stars of this stunning cluster.
Just as the moon and Jupiter appeared only along the same line of sight on March 13, so, too, will the moon and the Pleiades. The stars in this cluster lie some 440 light-years away (nearly three thousand trillion miles), or 11.5 billion times farther than the moon.
I hope you’ll step out at dusk this week to watch the crescent moon visit Jupiter and the Pleiades.
And be sure to set your clocks to the correct time … whatever that is!