Get ready for a close encounter of the celestial kind. On the afternoon of Jan. 26, the tiny asteroid 2023 BU will whiz only about 2,175 miles (3,500 km) from the Earth's surface. Before you bolt from your chair to get your affairs in order, know that the flyby will be perfectly safe. Even if by some chance the asteroid did strike the planet, it's so small — only about 16 feet across (3 meters) — it would shatter to bits in the atmosphere.
Small, automobile-size objects like 2023 BU are numerous and impact the planet about once a year . Crashing into the atmosphere at tens of thousands of miles an hour, they fragment and sometimes reach the ground as meteorites. These stones from space are eagerly sought by scientists and enthusiasts alike. In fact, on Jan. 21, hundreds of people across Kansas, Oklahoma and Texas reported a brilliant fireball that fortuitously dropped meteorites a few miles south of Muskogee. Coincidentally, that was the same date that amateur astronomer Gennadiy Borisov discovered 2023 BU.
When closest to Earth, the asteroid will fly over the ocean west of the southern tip of South America. Just prior to that it should be visible through a small telescope in dark skies over Namibia and South Africa, traveling at some 21,000 miles per hour (9.3 km/sec). Although Earth's gravity will change the object's orbit, it's moving much too quickly to get "sucked in" by the planet's gravity. After passing by safely, 2023 BU will obediently follow its orbit around the sun.
Still, it will be a close shave. Consider that the geosychronous satellites — the ones that relay communications and data around the globe — are located in a belt around the Earth some 22,200 miles (37,000 km) away. 2023 BU will briefly come 10 times closer. The audacity! Astronomer Gianluca Masi plans to live stream the the encounter on virtualtelescope.eu starting at 1:15 p.m. Central Time on Jan. 26. Stop by for a look if you can.
While few of us will directly see this car-sized rock, you can look at a different one with just a pair of binoculars. Pallas , the third largest asteroid known with a diameter of 318 miles (512 km), is sailing through the constellation of Canis Major the Big Dog this month. Sailing might be an exaggeration. More like creeping. Each night it moves about half-a-full-moon diameter to north-northwest, an amount easily noticeable in 8x or 10x binoculars or in any telescope.
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Pallas shines at magnitude 7.6 or about the same as the planet Neptune. While you can't see it with the naked eye, binoculars will show it as a faint star from outer suburban areas and the countryside. German astronomer Heinrich Olbers discovered the object in March 1802 and named it for Pallas, an alternate name for Athena, the Greek goddess of wisdom.
The asteroid spins on its axis once in 7.8 hours and circles the sun every 4.6 years. Its orbit is steeply inclined to the solar system plane, the reason Pallas lies so far from the ecliptic , the path the planets, sun and moon follow through the zodiac constellations.
While we're on the topic of the ecliptic, the waxing moon marches ever higher above the western horizon this week. As it does it will encounter each planet in turn. On Wednesday, Jan. 25 the banana crescent will be in conjunction with the planet Jupiter and make a beautiful sight at dusk. No telescope needed. Your eyes will do!
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