TNB Night Owl – 3200 Phaethon

Orbit illustration of 3200 Phaethon by Tomruen

Every December, the Earth passes through a trail of rocky dust that orbits our Sun. We earthbound mortals experience that dust as the Geminids meteor shower, one of the most prolific and grand light shows in the night sky which can be enjoyed without a telescope or binoculars.

Astronomers estimate the Geminids dust cloud began to form about a thousand years ago, but until the nineteen-eighties the source was unknown. Other meteor showers were known to be associated with comets. It’s now thought that the Geminids is the only meteor shower not caused by debris from a comet.

In 1983 the Infrared Astronomical Satellite (IRAS) team discovered a near-Earth object orbiting the Sun in such a tight elliptical orbit that it brushes by our star within 21 million km (13 million miles) at perihelion (meaning the closest approach to helios, the Sun). It takes 523 days to complete one orbit, and occupies the identical orbit of the Geminids.

Without a doubt, this near-Earth object is the source of the Geminids meteor shower. Named after the son of the Greek sun god Helios, the object was designated 3200 Phaethon by the Minor Planet Center, which is part of the International Astronomical Union (IAU).

Phaethon (FAY-uh-thon) is officially classified as an asteroid, although one theory holds that it may be the dead, rocky core of an extinct comet. However, if only comets shed dust, and if Phaethon is not a comet, where is the dust coming from? Another theory suggests that as the asteroid passes the Sun, it heats up which causes dust and debris to flake-off or break-off the mountain-size rock.

With a diameter of 5.10 km (3.2 miles) according to NASA, Phaethon is rightly designated as a Potentially Hazardous Asteroid (PHA). It’s not just the size that makes it dangerous: it’s path crosses the orbits of Mercury, Venus, Earth, and Mars. In Greek mythology, Phaethon loses control of his father’s chariot and almost destroys the Earth. Well, that’s a bit foreboding, isn’t it?

On December 16, 2017, Phaethon came within approximately 10.3 million km (6.4 million miles) of Earth, which is around 27 times the distance between the Earth and moon. On December 17, 2017, it was radar-imaged by the radio telescope at the Arecibo Observatory, Puerto Rico. It will not come as close to Earth again until December, 2093.

Although Phaethon would cause unimaginable destruction if it ever collided with Earth, astronomers are absolutely certain that there is no danger of a collision for at least the next 400 years.

(In an Obi-Wan Kenobi-like voice)…
This isn’t the SMOD you’re looking for.



Question of the night: Have you made any New Year’s resolutions for 2020?

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About Richard Doud 89 Articles
No one is right all the time. No one is wrong all the time. No exceptions to these rules.