Two Asteroids Will Cruise By Earth Today, Nearly Two Weeks After They Were Discovered

Two near-Earth asteroids approaching our planet.
NASA

Two recently discovered asteroids will be making a close approach to Earth later today, NASA’s Center for Near-Earth Object Studies (CNEOS) has announced. First spotted less than two weeks ago, the asteroids will buzz Earth in the afternoon, safely passing by our planet about one hour apart.

The double asteroid flyby comes just one day after a relatively tiny, 49-foot space rock darted past Earth in the pre-dawn hours of Saturday morning, coming in at under 1 million miles from the planet’s surface.

While not particularly hefty, today’s celestial visitors fare a lot better size-wise. According to NASA’s Jet Propulsion Laboratory (JPL), the space rocks are known as asteroids 2019 SZ4 and 2019 TH, and are estimated to measure as much as 137 feet and 144 feet in diameter, respectively. Both objects were picked up by NASA asteroid trackers on September 24. After a thorough study of their orbital path, the space agency classified the two rocks as Apollo-type asteroids.

As NASA explains, this designation is closely linked to the rocks’ orbits around the sun and indicates that the asteroids have the potential of being “Earth-crossing.” Apollo asteroids get their name from the famous asteroid 1862 Apollo, and all share a common trait — they zip through the solar system on an orbit that occasionally allows them to intersect that of Earth’s.

Screen capture showing the orbit of asteroid 1862 Apollo, a nearly mile-wide space rock that orbits the sun once every 651 days.
Screen capture showing the orbit of asteroid 1862 Apollo, a nearly mile-wide space rock that orbits the sun once every 651 days. NASA / Wikimedia Commons

The first one to dart past Earth later today will be asteroid 2019 SZ4. The 137-foot space rock is expected to approach Earth at 6:52 p.m. ET. Traveling through space at a cruising speed of a little over 14,500 mph, or nearly 19 times the speed of sound, the rock will harmlessly fly past our planet at a distance of 4.45 million miles. To put that into perspective, that’s 18.64 times the distance between Earth and the moon.

According to a report released last week by the JPL, the upcoming flyby will be the rock’s closest approach to Earth in 36 years. Although only recently discovered, the asteroid is not new to our corner of the solar system and occasionally swings by Earth as it orbits the sun once every 424 days. The last time asteroid 2019 SZ4 paid Earth a visit was in 1990, when it flew at a staggering distance of 18 million miles. Before that, the rock shot past Earth in 1983, coming within 5.1 million miles of the planet’s surface.

The asteroid will return next year and then again in 2048 and 2049. However, it will never come as close to Earth as it will today, drifting increasingly farther away from the planet’s orbit.

A near-Earth asteroid approaching our planet.
  urikyo33 / Pixabay
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The second space rock to visit Earth today will swing by a little under an hour after its predecessor. Asteroid 2019 TH will swoop in for its close encounter with Earth at 7:47 p.m. ET, the JPL announced earlier this week.

At 144 feet wide, this second celestial visitor is slightly larger than its predecessor. At the same time, the rock is faster and will creep in a little closer to Earth, as well. Hurtling through the void of space at over 25,600 mph, the asteroid will shoot past Earth at a distance of 3.48 million miles, or 14.62 times the distance to the moon.

Today’s close flyby will mark the first trip through the inner solar system for the speedy asteroid, which orbits the sun once every 337 days. The rock won’t return to our corner of space for a very long time. Its next visit is estimated to occur 173 years from now, in early 2192, and will only bring the asteroid some 46.5 million miles from Earth.