The Significance of Dimorphos’ Tail

As of writing, Dimorphos has a 10,000 km long tail, some two weeks after NASA slammed a space probe into it.

The tail may simply be due to the solar wind dragging debris with it into space. If so, we should soon see the tail disconnect from the asteroid. Whereupon it drifts off as an elongated cloud, separate from the asteroid.

However, if this doesn’t happen, we must conclude that the asteroid has become a comet of sorts.

Comets

Comets have tails that persist over time. Not because they’re dirty snowballs. But because the environment comets travel through is constantly changing in charge density.

Going towards the Sun, comets adjust for higher charge density. Going away from the sun, they adjust to lower charge density. To achieve these adjustments comets shed material through electrochemical processes and possibly nuclear fission.

These processes produce oxygen, which combine with protons in the solar wind to make water. Hence, the water rich tail of comets.

Circular vs oblong orbits

Contrary to comets, planets don’t have tails. This is because planets have near circular orbits. So, there’s no need for readjustments when it comes to charge density.

The difference between a comet and a planet is therefore due entirely to the shape of their orbits. Only objects with oblong orbits have tails.

So, if Dimorphos’ tail proves persistent, we can explain this as follows.

• Before the impact, Dimorphos had no tail because it was orbiting in a circle around Didymos.
• After the impact, Dimorphos acquired a tail due to its new and oblong orbit.

Didymos is no sun. But it’s surrounded by a charge gradient, and Dimorphos is a heap of rubble from which dust can easily be dislodged. As such, the two asteroids represent a miniature system comparable to the solar system.

Stability of orbits

When it comes to orbits, I believe that they are more stable than generally thought. Because orbits are governed by both gravitational attraction and electrical repulsion.

Gravity acts from the center of bodies while electric repulsion acts from the surface of bodies. When combined, these forces act as a shock absorber. So, orbiting bodies hit by an external forces regain their circular orbits relatively quickly.

In the case of Dimorphos, we can add an extra source of stability. Namely the solar wind which acts like an external power supply.

This may influence where the ideal orbit of Dimorphos should be relative to Didymos. If so, we may see the disturbed orbit steady into a circle a lot quicker than expected. It may even restore itself completely.

The legend of Venus

If we’re lucky, we’re about to witness a miniature reenactment of what may have happened some 10,000 years ago. Back then, according to legend, Venus settled into its current orbit after a turbulent journey from Jupiter to where it’s currently located.

Historic records everywhere on Earth depict Venus as either a goddess with long flowing hair, or a god with a long beard. This indicates that Venus had a tail relatively recently. However, this tail disappeared once Venus settled into her current orbit.

So, it appears that Venus went from being a comet to a planet in less than 10,000 years.

Conclusion

If Dimorphos steadies into a circular orbit quicker than expected, we’ll have supporting evidence for the theory that Venus was once a comet. If Dimorphos retains its tail until its orbit is near circular, we have additional evidence for this theory, and if the orbit gets completely restored, the evidence becomes even stronger.

So, NASA’s experiment may turn out to be more revealing than anyone had thought.

By ESA/Hubble, CC BY 4.0, Link

Developments since original publication

It appears that Dimorphos’ tail became a (semi)persistent feature:

NASA’s description of the above image

This NASA/ESA Hubble Space Telescope image of the asteroid Dimorphos was taken on 19 December 2022, nearly four months after the asteroid was impacted by NASA’s DART (Double Asteroid Redirection Test) mission.

Hubble’s sensitivity reveals a few dozen boulders knocked off the asteroid by the force of the collision. These are among the faintest objects Hubble has ever photographed inside the Solar System.

The ejected boulders range in size from 1 metre to 6.7 metres across, based on Hubble photometry.

They are drifting away from the asteroid at around a kilometre per hour. The discovery yields invaluable insights into the behaviour of a small asteroid when it is hit by a projectile for the purpose of altering its trajectory.

Image Description:

The bright white object at lower left is the asteroid Dimorphos. It has a blue dust tail extending diagonally to the upper right. A cluster of blue dots surrounds the asteroid. These are boulders that were knocked off the asteroid when, on 26 September 2022, NASA deliberately slammed the half-tonne DART impactor spacecraft into the asteroid as a test of what it would take to deflect some future asteroid from hitting Earth. Hubble photographed the slow-moving boulders in December 2022.