Have you heard the buzz about a big – very big – asteroid that’ll pass close in April? We have! No, it won’t hit our planet. In fact, it won’t have any effects on Earth. Still, excitement is building among both professional and amateur astronomers about the upcoming flyby of asteroid (52768) 1998 OR2 – the biggest asteroid due to fly by Earth this year – coming closest on April 29, 2020. This space rock is probably at least a mile wide (1.8 km) and maybe 2 1/2 times that big (4.1 km). Closest approach is April 29 around 5:56 a.m. Eastern Daylight Time (09:56 UTC; translate UTC to your time). Professional observatories are already pointing their telescopes at the huge space rock. Amateur astronomers with smaller telescopes will have an opportunity to see it as a slow-moving “star” very soon; if that’s you, we give charts and tips for observers at the bottom of this post that should help.
No access to a telescope? No problem. The Virtual Telescope Project in Rome will host a free, online public viewing of the asteroid on April 28, 2020.
Let’s make absolutely clear that there’s no chance of a collision between this asteroid and Earth. Asteroid (52768) 1998 OR2 will pass at some 4 million miles (6 million km), or about 16 times the Earth-moon distance. It’s true the object is classified as a Potentially Hazardous Asteroid. The Center for Near Earth Objects defines such an object as one that comes as close to Earth as:
In other words, such objects are reasonably close and reasonably big. And do we need to say there are a bunch of objects like this? Wikipedia lists 22 of the largest here. Recent decades have revealed more and more asteroids orbiting the sun, as the video below from NASA’s Jet Propulsion Laboratory shows:
None of the 22 Potentially Hazardous Asteroids listed by Wikipedia is known to be on a collision course with Earth in the foreseeble future. In fact, none of the asteroids in the video above is known to be on a collision course. Likewise, asteroid (52768) 1998 OR2 isn’t on a collision course with Earth, not anytime soon. The orbit of this asteroid is well known for at least the next 200 years. Its closest approach to Earth in this century and the next will happen in 2079, when it’ll swoop to within about a million miles of Earth (still about four times farther away than the moon). That 2079 sweep past Earth will still be a big deal. Asteroid (52768) 1998 OR2 is the largest known of all large Near-Earth Objects that’ll pass less than five times the Earth-moon distance over the next two centuries!
Astronomers at Arecibo Observatory in Puerto Rico will study asteroid (52768) 1998 OR2 from April 8 to 24, 2020, as the space rock travels through space at 19,461 miles per hour (31,320 km/h).
The high resolution radar images that will be obtained from Arecibo should provide scientists a better estimate of the space rock’s size and shape.
During its April 2020 pass, this asteroid will at no time be bright enough to view with the unaided eye. However, it’s estimated to reach a visual magnitude of around 10 to 11, which means observers with at least 6-inch or 8-inch telescopes (the number indicates the size of the primary mirror) will see the asteroid (very slowly) moving in front of the stars!
Sky enthusiasts can initially use a wide-angle (32mm or 35mm) eyepiece to point the telescope to a reference star in the asteroid’s path (charts below). After being assured that the instrument is pointing at the correct patch of the sky, a 26mm or 27mm eyepiece is recommended to detect the asteroid’s slow motion. You will want to note the star field, and watch for the object that moves over a period of about 10 to 15 minutes. Yes, that’ll be the space rock.
There will be closer approaches of asteroids in the future, including Apophis, which – although smaller – will pass very close to Earth in 2029. Another, larger space rock – 2 miles (3 km) wide – designated as asteroid (415029) 2011 UL21 will pass slightly farther than (52768) 1998 OR2 in June 2024.
But the upcoming flyby in April 2020 of asteroid (52768) 1998 OR2 is the most significant close approach of an asteroid until 2027, as another huge asteroid known as (4953) 1990 MU will safely pass by Earth at 12 lunar distances.
Astronomers first discovered asteroid (52768) 1998 OR2 on July 24, 1998, from Haleakala Observatory, Hawaii.
Bottom line: The huge asteroid known as (52768) 1998 OR2 will pass closest to Earth on April 29, 2020. Observers peering through telescopes will see it as a slow-moving “star.” Charts, tips – plus how to watch online – here.
Eddie Irizarry of the Sociedad de Astronomía del Caribe (Astronomical Society of the Caribbean) has been a NASA Solar System Ambassador since 2004. He loves public outreach and has published multiple astronomy articles for EarthSky, as well as for newspapers in Puerto Rico. He has also offered dozens of conferences related to asteroids and comets at the Arecibo Observatory.
Asteroid 33012EddieIrizarry, a 7.8 km space rock, has been named in his honor.