Elusive Mercury, usually too close to the sun to be seen, is at its most visible in the coming week. In contrast, one of the biggest, closest moons of the year will be … invisible.
Starting Saturday January 25, Mercury will no longer be cloaked in the glow of sunset or sunrise, Earthsky.org tells us.
“Mercury has come out of hiding to put on perhaps its clearest show of the year for mid-northern viewers,” Earthsky.org reports. “It will be at its best from about January 24th to February 4th.”
The fleet-footed, fast-moving planet, named after the Greek winged messenger, will be at its highest on January 31, viewable in mid-northern latitudes above the west-southwest horizon for half an hour after sunset, Earthsky.org said. It will set only as full darkness descends.
The best way to see Mercury is to head out just after sunset and aim your gaze at the west-southwest. The more unobstructed the horizon, the better. The planet will get brighter-looking as the sky gets darker.
The other phenomena taking place in the skies next week is a supermoon. But it won’t glow brightly as the ones we are used to hyping. This one is dubbed a Black Moon, because it is an invisible new moon.
It’s not the first invisible super moon of 2014, in fact. This is actually the second new moon within the month of January. What makes a moon super is not the fullness, but the proximity, astronomers say.
The term supermoon was actually coined by an astrologer by the name of Richard Nolle, who defined a supermoon as “a new or full moon which occurs with the moon at or near (within 90 percent of) its closest approach to Earth,” according to Earthsky.org. That means that it must come within 224,851 miles of Earth, since the moon’s distance ranges from 225,623 miles to 252,088 miles, as measured from the center of each body, according to Space.com. The average distance is 238,855. The change is because the moon’s orbit is elliptical.
The first supermoon of the year came on the first day of the year. On January 1 the moon was a mere 221,782 miles from Earth. But, with the sun on its far side, it was invisible to all but the tides. That was the first so-called Black Moon of 2014. The second comes next week, on January 30. There are five super moons this year, but the visible ones will be in July, August and September.
A supermoon heightens tides, so the tides next week will be more pronounced than usual, Earthsky.org says. They are known as spring tides, but it’s nothing to do with the time of year.
“Spring tides—so called because the water ‘springs up,’ not because of the season—occur when the moon, the sun and Earth are aligned, during a full moon or new moon,” Space.com explains. “The gravitational forces of the moon and the sun both contribute to these especially strong tides.”
Our satellite influences more than tides, though.
“The moon's gravitational pull stabilizes Earth's wobble on its axis, leading to a stable climate,” Space.com notes. In other words, the moon’s very presence makes life on Mother Earth possible.
Another fun, though slightly unnerving fact: The moon is literally inching away from us year by year, Space.com says. Each year it drifts 1.5 inches farther away.