cosmifeed.

Mission

The hunt for Planet X

Could a hidden ninth planet be out there, past Neptune? SPHEREx's infrared maps give everyone a way to look.

SI-generated

SI-generated video of a generic telescope. Not a real spacecraft and not SPHEREx data.

Why some scientists think it might exist

Far past Neptune, a handful of small icy worlds travel on long, stretched orbits that seem to point the same way.

One idea is that the pull of an unseen planet, several times Earth's mass, keeps them lined up. Other scientists think it's chance, or how we happened to look.

It has not been found. It is an idea, not a discovery.

Why infrared helps

A planet that far away gets almost no sunlight, so it would look very dark to ordinary cameras.

It would still give off a little heat. Infrared light is how we see heat.

SPHEREx maps the whole sky in 102 infrared colours, again and again, so the same patch can be compared on different dates.

How you can help

  1. 01

    Compare dates

    Flip between two dates of the same patch of sky.

  2. 02

    Look for movement

    A far planet moves a tiny bit between dates; stars stay put.

  3. 03

    Check the Sky Map

    See where each picture sits on the sky.

  4. 04

    Flag it

    Press and hold in the Discovery Lab. Reviewers check flags against known asteroids.

Being honest

  • Nothing on CosmicFeed is a confirmed discovery. Flags are leads for people to check.
  • Independent project, not operated or endorsed by NASA.
  • SPHEREx pictures are real data. SI never makes or edits them.
Read the full SI disclosure →
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