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Machine Learning · head to head

Ray vs Stellarium

Ray logo

Ray

Machine Learning

Scale AI and Python applications

From
Free
Rated
-
Full reviewWebsite
Stellarium logo

Stellarium

Education

Free open source desktop planetarium software, distinct from the paid Stellarium Mobile Plus app

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Ray windows support is beta and multi node Ray clusters are untested on Windows; Stellarium it is desktop-only software, so it has no native touch-optimised phone interface; the similarly named mobile app is a different paid product from a different company.
  • They diverge on capability: Ray covers Distributed computing, Stellarium covers Photorealistic sky rendering.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Ray and Stellarium actually diverge.

Attributes where Ray and Stellarium differ
AttributeRayStellarium
Pricing modelfreemiumOpen source, no licence fee
PlatformsLinux, Mac, WindowsWindows, macOS, Linux
CategoryMachine LearningEducation
Founded2019Unknown

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Ray

  • Distributed computing
  • Ray Train
  • Ray Tune
  • RLlib
  • Ray Serve
  • PyTorch
  • TensorFlow
  • Hugging Face

Only in Stellarium

  • Photorealistic sky rendering
  • Large object catalogue
  • Telescope control
  • Scripting engine
  • Free and open source
  • Plugin ecosystem

What people use each for

The jobs each tool is most often brought in to do.

Ray

  • Distributed AI model training and servingnot Stellarium
  • Large-scale data processingnot Stellarium
  • Reinforcement learning workloadsnot Stellarium
  • ML inference servingnot Stellarium

Stellarium

  • A student or educator wanting a serious, scriptable planetarium tool without a budget line itemnot Ray
  • An amateur astronomer wanting telescope control from desktop software they can inspect and modifynot Ray
  • Someone running a planetarium display or public astronomy event on a scripted shownot Ray
  • A hobbyist who wants a large object catalogue without paying a subscription, and does not need a phone appnot Ray

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Ray

  • Windows support is beta and multi node Ray clusters are untested on Windows
  • Windows lacks copy on write forking, which raises memory requirements, and Ray code assumes UNIX filenames
  • Multi node clusters are untested on Apple Silicon Macs
  • The Java API is experimental and community supported only, and requires matching Java and Python versions
  • Python 3.13 support is beta

Stellarium

  • It is desktop-only software, so it has no native touch-optimised phone interface; the similarly named mobile app is a different paid product from a different company.
  • As a volunteer-maintained open source project, support is community-based rather than a guaranteed commercial help desk.
  • The interface, while capable, is less immediately intuitive for a first-time user than a polished commercial phone app.
  • Telescope control and some advanced plugins require additional setup that a non-technical user may find fiddly.
  • Because it shares a name with the unrelated paid Stellarium Mobile Plus app, buyers researching pricing online can easily conflate the two products.

Pricing, plan by plan

Ray

Free
  • Open SourceFree
    • Full Ray framework
    • All libraries
    • Community support
  • Anyscale PlatformFree
    • Managed infrastructure
    • Enterprise support
    • SLAs

Stellarium

Free
  • Stellarium DesktopFree
    • Full software, GPL licensed
    • No account, ads or subscription
    • Community-developed plugins

Which should you pick?

Choose Ray if

  • You need distributed computing.
  • You want to start without paying.
  • You work on Linux, Mac, Windows.
  • You also want ray train.
Ray review

Choose Stellarium if

  • You need photorealistic sky rendering.
  • You want to start without paying.
  • You work on Windows, macOS, Linux.
  • You also want large object catalogue.
Stellarium review

Questions people ask

Is Ray or Stellarium better?
Neither clearly leads. Ray starts at Free and Stellarium at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Ray or Stellarium?
Ray starts at Free and Stellarium at Free.
Does Ray or Stellarium run on more platforms?
Ray runs on Linux, Mac, Windows. Stellarium runs on Windows, macOS, Linux.
Can I use Ray for free?
Both have a free tier, so you can try either at no cost before committing.
What is Ray best used for?
Ray is most often used for distributed ai model training and serving, large-scale data processing, reinforcement learning workloads, ml inference serving. Of those, distributed ai model training and serving and large-scale data processing are not what Stellarium is typically brought in for.
What can Ray do that Stellarium cannot?
Ray covers Distributed computing, Ray Train, Ray Tune, RLlib. Stellarium covers Photorealistic sky rendering, Large object catalogue, Telescope control, Scripting engine.

Answered from the vendors’ own pages

Ray: Is Ray free?

Yes. Ray is free and open source software with over 34,800 GitHub stars and 1,000+ contributors. Users can download and use the Ray framework at no cost.

Source
Stellarium: Is Stellarium really free?

The desktop software is free and open source under the GPL licence. The separate mobile app, Stellarium Mobile Plus, is a different paid product.

Ray: Is there a paid option for Ray?

Yes. Anyscale, the managed platform built by Ray's creators, offers paid tiers with enterprise features like governance and advanced tooling. Specific Anyscale pricing details are not listed on the Ray website.

Source
Stellarium: Is the mobile app made by the same team?

No. Stellarium Mobile Plus is built by Noctua Software, a different company, and is sold on subscription.

Ray: Can I try Ray with credits?

Yes. New users can try Ray with $100 credit on Anyscale's managed platform to explore the service.

Source
Stellarium: What platforms does the free version run on?

Windows, macOS and Linux desktop.

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