Is it found in either the Sol or Alpha Centauri solar systems?
Yes.
Is it another, or on another, real life planet?
Yes.
Is it found on this planet?
Assuming you're currently on Earth, no.
Is it larger than Earth?
No.
Is it mostly fluid?
No.
Is it Pluto?
No.
Y'all gotta toss out a few traditional questions too!
Is it alive?
No.
Is it cold by Earth standard?
Yes.
Is it a gas giant?
No.
Is it larger than Australia?
Yes.
Is it a famous feature on a planet?
No.
What happened to our larger than Australia space mystery?
I forgot about it and then felt awkward answering after two weeks. Like most forms of procrastination, this just made it three weeks instead.
Is it an asteroid?
No.
Is it red?
Yes.
Is it larger than Mars?
No.
Is it smaller than our moon?
No.
Does it have liquid of any type on it?
This is controversial!
Not Earth. Not Pluto. It exists in reality. It is a red object found in either the Sol or Alpha Centauri solar systems. It is not found on Earth. It is no smaller than Earth’s moon and no larger than Mars. It is cold by Earth standards, well the standards of the local Earthlings. It is not a gas giant, not made mostly of fluid, and whether it contains liquid is controversial. It is not an asteroid, and is not a famous feature on any planets.
((What do you think of my description of the culmination of the answers?))