Space and Astronomy News for the 6th of September 2025

The Earth has another moon

Say G'day to the Earth newly discovered quasi moon, 2025 PN7!

Just in time for this weekend's total Lunar eclipse, astronomers have found another quasi moon, called 2025 PN7 for now. We have one permanent Moon which we all know about. The Earth also has a number of other, small rocky bodies that orbit the Sun long with our home planet. We've known about seven of these and this discovery this week of PN 2025 brings the number to eight. 

A diagram showing how another quasi moon discovered in 2026, Kamo'oalewa, orbits the Sun along with the Earth. Image via NASA JPL

These small bodies are not in stable orbits around the Earth and will eventually leave the vicinity in a few hundred or thousand years. Their orbits are complex and not stable. This new moon was discovered on August 29th 2025 by the Pan-STARRS observatory. A number of other observatories also confirmed the results. You can see the announcement here.

Going back through other images, it seems that 2025 PN7 was first spotted back in 2014. It seems to have been a quasi moon for about 60 years and likely to remain one for another 60 years or so. Astronomers have established that other quasi moons are the result of a meteorite hitting the Moon and throwing rocks into space. Such objects are called lunar ejecta.

In a post in the Minor Planets Mailing List (MPML), Alan Harris from the Space Science Institute, stated that 2025 PN is travelling too fast compared to Earth of 3.4 km/s or 12,240 km/h to be lunar ejecta. He adds that it's "most likely just an asteroid that has trickled into a near-Earth orbit from the inner main belt."

It's likely to be pushed away from Earth. "Some future close encounter with Earth could put it on an orbit that intersects either (or both) Mars or Venus," Harris continued.

There's no formal name for this new moon and sadly, you won't  be able spot this small body in your telescope either.

Astronomers are preparing to observe the interstellar comet 3I/ATLAS as it passes near Mars on October 3, 2025

It might be some the best observations of interstellar comet 3I/ATLAS will be from Mars, not Earth.

In about a month, the third visitor to the Solar System we've found so far, comet 3I/ATLAS, will be around 30 million kilometres from Mars, compared to its closest approach to Earth of about 168 million kilometres. While there's no telescopes on the red planet, there are a number of sophisticated spacecraft in orbit above it. 

A recent image of interstellar comet 3I/ATLAS captured by the Hubble Space Telescope. Image via: NASA/ESA/David Jewitt (UCLA)

The European Space Agency's Colin Frank Wilson, project scientist for their Mars orbiters, says their spacecraft will be used to observe 3I/ATLAS. Both the  Mars Express and the ExoMars Trace Gas Orbiter (TGO) will be used.  These orbiters were not designed to make such observations, but will possibly provide some good results.

"We will attempt to obtain images of the object using the High Resolution Stereo Camera (HRSC) onboard Mars Express, and also with the Colour and Stereo Surface Imaging System (CaSSIS) onboard TGO," Dr. Wilson said.

Astronomers are also planning to use ESA's Jupiter Icy Moons Explorer (JUICE) spacecraft for observations of 3I/ATLAS as well.

Next week, a Saturn is at opposition!

Cheers,

Earl White 

BINTEL

6th September 2025