A new dwarf planet might have been found by the Rubin Observatory

A possible new world in the icy outskirts of the Solar System 

An illustration showing the predicted orbital path of 2026 ED138. The Earth and other rocky planets are in the small loops around the Sun in the middle of the diagram.

No doubt the astro big news this week is the announcement of the discovery of a candidate for the Solar System's 6th dwarf planet by the Vera C. Rubin Observatory. 

The object was found in images taken on 20 nights between 4 March and 11 July and uncovered by Rubin Operations team member and in-kind contributor Matthew Holman. Matthew works on algorithms to improve Rubin's Solar System imaging capabilities. 

2026 ED138's orbit is tilted almost 25 degrees off of the plane of the Solar System. This points towards it being disturbed from its original orbit through gravitational interactions with Neptune. It's currently located some 46 astronomical units (AU) or about 6.9 billion kilometres from the Sun. By comparison, Pluto averages about 40 AU from the Sun.

It was also found close to the plane of the Milky Way where it was hidden away from other observations in the crowded fields containing millions of background stars.

Now it's been revealed and its location and orbit established, other observatories will join in to collect more data on 2026 ED138. 

What is a dwarf planet?

Pluto was originally the 9th planet in the Solar System following its discovery in 1930. The problem was that astronomers kept discovering other Pluto-like bodies and the question boiled down to this: if Pluto is a planet, why shouldn't the others be as well? How many of these smaller planets might we end up discovering in the Solar System?

The term dwarf planet was coined to describe these bodies that are similar to Pluto. There's still a lot of debate around what is a dwarf planet. Should dwarf planet sized moons around larger planets be included? For example, Jupiter's moon Ganymede is even larger than Mercury so why shouldn't it get a gong? Our Moon is much larger than Pluto as well.

What are the other dwarf planets?

The IAU recognises five dwar planets. They are:

• Pluto
• Ceres
• Haumea
• Makemake
• Eris

Some disagree with this number. Wikipedia, for example, states there at least nine dwarf planets.

Read some more background info at the NASA Science site. 

Can I see this new dwarf planet with my telescope?

No. 

Even though it's quite large, the distance and difficulty of tracking it against the background of stars would make it next to impossible to spot. Even with all the major observatories around the world and multiple telescopes in space, it was only confirmed to be a dwarf planet from Rubin observations this year. Professional telescopes can detect 2026 ED138, and it has been identified in archival images dating back to 2016. Rubin revealed what it was and how it was moving,

We only have it basically as a spot of light and would likely require a visit from a spacecraft many years into the future to obtain any surface details. 

It's possible to spot Pluto with a large amateur telescope if you know exactly where it's located in the night sky. It will appear to your eyes as an extremely faint "star". The main excitement is knowing that you're actually looking at Pluto. No other dwarf planet apart from Ceres,  which is much closer to us, can be seen this way.

How big is 2026 ED138?

It's estimated to be somewhere between 600 and 1,500 km in diameter.  More observations will be needed to refine this figure further. This would make it one of the larger dwarf planet candidates found beyond Neptune

Are there other large objects in the Solar System we haven't found yet?

While we can't say for sure as we haven't found them yet, the chances of other bodies the size of 2026 ED138 or even larger are pretty high. One of the advantages of a large telescope such as Rubin that can scan the entire sky visible from its location every few nights is that it can spot anything that appears to move from night to night. Stars will appear static* but even a distant dwarf planet in the Solar System might give itself away by its movements. 

Some astronomers have suggested Rubin could find hundreds or even thousands of dwarf planets in the extreme regions of the Solar System. 

What about "Planet IX/Planet 9?" 

Planet IX refers to a long-theorised ninth major planet in the Solar System which has not been found yet despite some tantalising clues, including disturbances to known outer Solar System bodies. (We chatted about this in older blog articles like this one.) 

If it's there, having Rubin produce these types of observations does increase the chances of us finding it. It will still take a remarkable effort to sift through and analyse the vast amounts of data that Rubin produces every night. Even with latest data-analysis and AI tools this will be a momentous task!

That 2026 ED138 name is a bit dodgy. Is it likely to change?

Yes, a permanent name could eventually be assigned by the IAU (International Astronomical Union) once the discovery is confirmed. 

There's a lot more information about 2026 ED138 at the Rubin Observatory site which can be found here.

NASA speeds up its plans to return humans to the Moon

2028: Put that in your calendars for NASA to return humans to the surface of the Moon

Last weekend our time senior NASA leaders outlined the timeline for putting humans back on the surface of the Moon for the first time since 1972. 2028 is still the target for a crewed landing, but details of the sprint to reach this deadline have emerged. 

NASA Administrator Jared Isaacman has evoked the spirit of the Apollo program. 

"It's about our own history. It's a playbook this agency knows really well, the same playbook that went from Apollo 7 splashdown to Apollo 11 in just nine months," he said during a news conference at Kennedy Space Center.

Next year in 2027 Artemis III will test a range of hardware in low Earth orbit. Unlike the Artemis II mission earlier this year, this crew will not leave Earth orbit and travel to the Moon aboard NASA's Orion spacecraft.

A few people have commented that it's like the Apollo 9 mission which carried out similar tasks in Earth orbit. 

Two companies racing to deliver NASA’s lunar landers

SpaceX and Blue Origin are both developing Moon crew and cargo landers. One of the prime mission objectives of Artemis III will be to demonstrate rendezvous and docking capabilities between test versions of landers in space. At this stage, astronauts will enter Blue Origin’s test vehicle to evaluate its cabin and life-support systems, although the SpaceX Starship demonstration will involve docking without anyone climbing aboard.

Artemis III will need three launches over a short period. Blue Origin test lander, Orion with the crew itself, with the SpaceX following quickly.

"As a rocket nerd, it's going to be pretty awesome," said Amit Kshatriya, NASA's associate administrator.

The Artemis III rocket is now stacked. Image via: NASA

What's "in-space propellant aggregation approach"?

NASA's way of saying refuelling in orbit

A key part of the Artemis IV mission if SpaceX is chosen will be transfer of fuel from several "tanker" spacecraft launched from Earth where it will be loaded onboard the Moon bound lander.  Artemis V and subsequent Moon landing missions will require multiple rocket launches. 

This is in contrast to the Apollo program where everything that was needed for the Moon landing and return was launched aboard a single Saturn V rocket. 

While technology is advancing quickly, large-scale orbital refuelling with cryogenic propellants remains a major technical challenge.

Both companies have also revised their landing plans. SpaceX now proposes docking its Starship lander with Orion in Earth orbit, then using Starship to propel the joined spacecraft towards the Moon. Blue Origin will initially use expendable transfer stages, postponing the need for its own in-space refuelling system. SpaceX’s approach still requires orbital refuelling. Both providers must demonstrate their landers without astronauts before a crewed landing.

Artemis IV is targeting the first landing in 2028, with Artemis V intended to follow later that year. NASA’s broader plan calls for more frequent missions, helping teams retain experience between launches rather than effectively starting again after lengthy gaps. 

NASA has also stated that the return to the Moon will be an ongoing program and not a set series of missions that will finish once a cert number is completed. 

The Artemis IV mission profile if the SpaceX Starship lander is selected by NASA

They are also aiming for roughly 10 robotic lunar deliveries a year starting in 2027, or close to one a month. Its announced goal is 30 robotic landings over three years, beginning in 2027, through the Commercial Lunar Payload Services (CLPS) programme.

All this activity is aside from other national space exploration programmes, especially from China. 

You can check out more at the NASA pages here and here.

The next couple of years are going to be an exciting time for space enthusiasts!

ZWO adds photometry features to the S30 Pro and S50 Pro Smart Telescopes

What is photometry?

You probably know that many stars change their brightness over time. Luckily for us, our Sun varies only by quite tiny amounts and produces light and energy at an almost constant, reliable level.

Variable stars do change their brightness as seen from Earth and often by a considerable amount. There are few different reasons for this. Intrinsic variable stars change their brightness or luminosity due to internal processes. Stars that do this on a very regular basis have been very useful yardsticks to help astronomers establish the scale of the Universe. Others such as Cataclysmic or Eruptive Variable stars undergo sudden and unexpected changes. Some stars of this type are known to have such events on an irregular schedule and observers keep an eye on them.

Extrinsic variable stars change in brightness because of other stars they orbit passing in front of them.  They might even have patches uneven brightness that changes as the star rotates.**

Photometry is a different activity from simply taking images of stars. It measures a star's varying brightness and records it.

Keeping track of variable stars and their changes is something astronomers of all levels carry out. It helps us learn more about stars, their structure and their evolution. This new ZWO update that includes photometry will allow you to do exactly that. This is a great feature for serious observers, students and anyone interested in citizen science projects to help track variable stars.

Like all other updates from ZWO, this current batch of new features is free and as simple to install as updating an app on your phone or iPad/tablet. 

If I find an exoplanet with my ZWO Seestar with this new feature, can I name it after myself (or my dog, cat, favourite footy team etc)?

We've actually had a couple of people asking us if this could be used to find exoplanets. You might be getting a little ahead of yourself!

Some exoplanets orbiting around other stars have been discovered by what's called the Transit Method. This is where a planet crosses in front of its host star. As it does, the light from the star will dip in brightness a little bit. And by a little bit, I mean an extremely small amount. 

The change is going to likely beyond that a ZWO Seestar can detect, but there will be folks taking a crack at it and best of luck. 

While the above-mentioned IAU will make a final decision, they're likely to listen to suggestions. And no, I don't have a contact there...

Cheers,

Earl White

BINTEL

31st Oct 2026

*Yes, stars, especially those close to us in the Milky Way "move" as part of their own orbits around our home galaxy. These movements called "proper motion" are exceedingly small and best observed over a period of years, not days. They're visible as movements of stars against a background of much further away members of the Milky Way.

**Again, a very brief introduction to a complex and fascinating topic. Let me know if you'd like more details!