For generations there has been speculation that the Earth may have more than one moon orbiting it.
Many claims have been made that a second moon has been spotted, but all have proven false. Even large pieces of orbiting debris from Soviet rockets initially have been mistaken for miniature moons.
This past April an asteroid named 2016HO3, between 40 and 300 meters in length, has been found in an orbit about the Earth, which qualifies it as a quasi-moon, if not a true mini-moon. It probably has been in Earth’s orbit for one century and likely has several more centuries to go before it returns to its journey through space. Its orbit is too distant for Earth’s gravity to permanently capture it orbiting as it does between 38 and 100 times the Earth-Moon distance.
“The relatively permanent orbit of 2016HO3 about the Earth gives it the status of a quasi-moon,” Paul Chodas of NASA’s Jet Propulsion Laboratory said.
This discovery raises questions as to 2016HO3’s origin. Did it somehow spall or split off of the true moon, or was it merely a passer-by that ventured too close to Earth and has been temporarily trapped for a time by gravity?
Focus on the planets
Three evening planets are so intertwined this month that they can be discussed together. Venus, Mercury and Jupiter form, from lower right to upper left, a diagonal line on the western horizon a half-hour after sunset as August opens. The crescent moon passes by Mercury on Aug. 4 and by Jupiter the following night. On Aug. 23 Mercury occupies the left base point and Venus the right base point of a triangle with Jupiter making up the apex. The big night is Aug. 27, when Venus and Jupiter are less than 0.1 degree apart, the closest conjunction of major planets for the year. And if this were not enough, along with Mercury all three planets fit within the field of a single eyepiece.
Saturn and Mars put on a show of their own as they occupy the southwestern evening sky as evening falls. Mars can be distinguished by rusty color by binoculars while Saturn is still tilted at an optimum angle to display its ring system and moons. On Aug. 8, it should be possible to spot at least five of Saturn’s moons, including Titan. On Aug. 23, Antares, Mars and Saturn form an ascending line on the southwestern horizon a half-hour after sunset.
Neptune can be seen as a blue-gray disk in Aquarius and Uranus as a blue-green disk in Pisces shortly after midnight. Use the Sky and Telescope finder charts at skyandtelescope.com/urnep to find these two planets.
August events
1 Sunrise, 5:21 a.m.; sunset, 8:02 p.m. Today is Lammas, a cross-quarter day, marking the midpoint between the summer solstice and fall equinox.
2 New moon, 4:45 p.m.
4 A thin crescent moon nestles beside Mercury on the western horizon a half-hour after sunset. Jupiter is far to the duos upper left while Venus, accompanied by Regulus, is to the lower right.
6 The moon lies within 0.5 degree of Jupiter tonight.
10 Moon in first quarter, 2:21 p.m. The moon is at apogee, or farthest distance from the Earth today. The sun is entering the constellation of Leo.
11 The moon passes by a triangle, whose base comprises Antares and Mars with Saturn at its apex.
12 Peak night for the Perseid meteor shower. The moon will set after 1 a.m. and should prove to be no problem during the predawn hours. Predictions range from 50 to 150 per hour of swift bright meteors.
18 Full moon, 5:27 a.m. The full moon of August is known as the grain moon or green corn moon.
22 Moon at perigee or closest approach to Earth for the month.
23 Antares, Mars and Saturn form an ascending line on the southwestern horizon a half-hour after sunset.
25 Moon in last quarter, 11:41 p.m.
27 Venus and Jupiter are less than 0.5 degree apart low on the western horizon about 45 minutes after sunset. This is the closest approach of two major planets for the year.
31 Sunrise, 5:56 a.m.; sunset, 7:15 p.m.
Send astronomical queries to Clair Wood at cgmewood@aol.com or care of the Bangor Daily News, Features Desk, P.O. Box 1329, Bangor, Maine 04402.