Strawberry Minimoon: Friday, June 9 Jun 8, 2017 18:28:22 GMT -5
Post by Joanna on Jun 8, 2017 18:28:22 GMT -5
Strawberry Minimoon: Friday, June 9
Tomorrow night, observers will see a special type full moon that comes only once a year: the minimoon, or a full moon that appears slightly smaller than usual. On June 9, at 9:09 a.m. (EDT), the minimoon will reach its fullest phase. At this time, the natural satellite will be below the horizon for observers in the continental U.S., but early risers in Hawaii and parts of Alaska will have a chance to see the minimoon at its fullest, weather permitting.
What’s a minimoon? A minimoon refers to a full moon that is at, or near, apogee, the point in the satellite’s orbit where it is farthest from Earth. This is essentially the opposite of a supermoon, which refers to a full moon that occurs at perigee, or the point where the moon is closest to Earth. Minimoons appear up to 14 percent smaller than supermoons and are slightly less luminous than regular full moons. Minimoons and supermoons happen because the moon’s orbit isn’t perfectly circular; it’s a tiny bit elliptical, with the Earth at one focus of the ellipse and the moon at the other. A line drawn through both foci of this ellipse would be the ellipse’s major axis, called the line of apsides by astronomers. The moon’s line of apsides rotates relative to the stars once about every 8.85 years. This means the apogee and perigee won’t always line up perfectly with a full (or new) moon. Sometimes, the perigee of the moon coincides with the moon’s first quarter, for example, and this is the reason supermoons and minimoons do not occur every month.
While minimoons and supermoons have slightly different apparent sizes than normal moons, these differences are probably too small for amateur observers to notice, Ernie Wright, lead visualizer at NASA’s Scientific Visualization Studio, days. “Ancient peoples were acutely aware of many things about the sky, certainly more than the average person is now,” he adds. “But I don’t believe anyone took note of the changing apparent size of the moon. The difference between the largest and smallest full moon is only 4 arcminutes, near the limit of what the naked eye can detect.” This is less than a sixth of the average diameter of the moon in the sky and one would have to compare it side-by-side to a moon that appeared several months earlier to really notice the size difference.
For most of human history, the moon was largely a mystery. It spawned awe and fear and to this day is the source of myth and legend. But today we know a lot about our favorite natural satellite.
A minimoon by many names. Among European colonists of the Americas, the June full moon was known as the Rose Moon. Celtic-speaking peoples called it the Moon of Horses. Some American Indians in the northeastern U.S. called this moon the Strawberry Moon, as June is when wild strawberries ripen in the region. This name was hardly universal, though (and the strawberry-ripening connection would vary, because the plant ripens earlier or later depending on location). Names among American Indians differed according to the local culture and environment: the Cherokees called the full moon of June the Green Corn Moon, because this was the growing season; and the Navajo called it a Planting Moon. The Tlingit peoples of the Pacific Northwest called the June full moon the Birth Moon.
Moonrise tomorrow night will be as follows: Bar Harbor, Maine, 7:20 p.m.; Baton Rouge, Louisiana, 8:15 p.m.; Billings, Montana, 9:04 p.m.; and San Diego, California, 8:07 p.m.
Sources: Jesse Emspak, Space.com, June 8, 2017, and Old Farmer’s Almanac.