Astro Bob: Asteroid 2023 BU buzzes Earth, Pallas pops and Jupiter meets moon

There's a lot happening with asteroids this week including an eye-catching Jupiter-moon conjunction.

2023 BU encounter
On Thursday, Jan. 26 at about 3:16 p.m. Central Time, the tiny asteroid 2023 BU will safely whiz some 2,175 miles (3,500 km) above Earth's surface. It's only about 16 feet (3 meters) across.
Contributed / Gary Meader illustration

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.

2023 BU orbit
Asteroid 2023 BU's orbit takes very close to the planet this week. This diagram shows a bird's-eye view looking back toward the Earth from above the plane of the solar system.
Contributed / NASA HORIZONS with additions by Bob King

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.

2023 BU photo
As you can see in this photo, taken on Tuesday, Jan. 24, BU is just a faint blip!
Contributed / Gianluca Masi

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 starting at 1:15 p.m. Central Time on Jan. 26. Stop by for a look if you can.

Asteroids Pallas
This is probably the best image taken to date of Pallas. It was made with the European Southern Observatory's Very Large Telescope and reveals the asteroid's crater-dimpled surface and a bright spot.
Contributed / ESO, P. Vernazza et. al.

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.


Pallas wide view
Pallas is moving northeast across Canis Major the Big Dog a little more than a fist below Sirius. You can find Sirius by shooting a line downward through Orion's Belt. Use the detailed map to pinpoint the asteroid's nightly location.
Contributed / Stellarium

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.

Pallas detail chart
In this zoomed-in map you can see how Pallas moves northward in the coming nights. The three bright stars in a triangle at the bottom of Canis Major will be your guide. Start there — at Adhara — and star-hop your way to the asteroid. Its position is shown nightly at 10:30 p.m. CST. You can also go out earlier or later than that time hunt it. On Jan. 25, Pallas passes extremely close to a star of similar brightness (HD 47186). They'll nearly touch around 9:30 p.m. CST.
Contributed / Stellarium with additions by Bob King

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.

Planets Jan 25
Jupiter and the crescent moon will be in conjunction on Jan. 25 with Venus and Saturn paired up closer to the horizon.
Contributed / Stellarium

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!

"Astro" Bob King is a freelance writer and retired photographer for the Duluth News Tribune. You can reach him at
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