EARTH GOT A “NEW MOON” - What You should Know about This New Moon

Now, technically, the Earth has a new moon.

It was discovered US astronomers Theodore Pruyne and Kacper Wierzchos using a 1.52-meter (60 inches) telescope at Mount Lemmon Observatory near Tuscon, Arizona on February 15, then shown to be on a chaotic orbit around the Earth as the Earth orbits the sun. That makes it a moon, a natural satellite.

Earth got a New Moon - Artist illustration (Credit: technous.net)

“Orbit integrations indicate that this object is temporarily bound to the Earth,” reads a notice from the International Astronomical Union. “Further observations and dynamical studies are strongly encouraged.” But while excitement about the discovery is growing, it is important to keep in mind that this moon isn’t as impressive as our main satellite. It is extremely faint – it is estimated to be only between one and six meters across – and won’t be with us for much longer.

Perspective view of the orbit of 2020 CD3 about the Earth. The white band is the orbit of Earth’s main, Permanent, Moon. (Tony873004)

Dramatic as it sounds, this new moon will not change your life. It will not move the ocean tides, as the Moon does. It will not hit your eye like a big pizza pie, not unless you have access to some serious telescopes. No man’s face is in it, and no one will ever step on it. It neither waxes nor wanes, from crescent to full. It will not reliably measure time, as the Moon always has, which lingers linguistically in the derived word “month.” Following observations enabled its orbit to be calculated, and at 22:53 Universal Time (UT) on February 25, the Minor Planet Center announced the discovery, designating it as 2020 CD₃, as the new moon is officially known and confirming that it is temporarily bound to the Earth.

Earth with its new moon (Credit: MARMDEL)

The capital-M Moon is special, and it takes a challenger satellite, this grasping little lunar arriviste, to remind us just how special it is. The object 2020 CD₃ is essentially just a tiny member of a class of asteroids whose orbits cross the Earth’s orbit. Occasionally, they come near or collide with the Earth, but in this case, a collision would not have been a catastrophe for us because 2020 CD₃ is so small that it would have broken up in the atmosphere before reaching the ground. 2020 CD3 came from away, probably from the solar system’s main asteroid belt between Mars and Jupiter, where it had previously been orbiting only the sun at a similar pace to the Earth. That similarity meant it approached Earth slowly enough to be captured.

This 'New Moon' came from away, probably from the solar system’s main asteroid belt between Mars and Jupiter (Artist illustration)

But the Moon was not captured. It was born of the Earth itself, in a collision nearly 5 billion years ago, when a smaller planet called Theia collided with the proto-Earth at a few kilometers per second. They call this the Big Splash, and it knocked Earth’s orbital axis off-center by 23 degrees, which is why we have annual seasons and, for the moment, polar ice caps. The Moon is also comparatively huge, about a quarter the diameter of Earth. Most moons are many more times smaller than their planets. You could fit 2020 CD3 in a pickup truck.

Also, the Moon is very close, only about 30 Earth diameters away, one of the most intimate lunar orbits. 2020 CD3 has passed by Earth a lot closer than that but only irregularly. Most moons are at a distance from their planet because they are formed along with the planets, out of a collapsing accretion disk of matter. If they were closer, they would eventually collide. The big moons are round because their own gravity shapes them that way, but there are some smaller irregularly shaped ones. It is rare for a moon to be captured into a stable planetary orbit. The most recent moonlet captured even into temporary orbit by Earth’s gravity was 2006 RH120, a similar-sized asteroid that was in orbit for a few months ending in June 2007.

Reference original source: The Conversation and National Post

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