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Machine Learning · head to head

Milvus vs Stellarium

Milvus logo

Milvus

Machine Learning

Open-source vector database for scalable similarity search

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: Milvus vector dimensions are capped at 32,768; 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: Milvus covers Billion-scale vectors, Stellarium covers Photorealistic sky rendering.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Milvus and Stellarium actually diverge.

Attributes where Milvus and Stellarium differ
AttributeMilvusStellarium
Pricing modelfreemiumOpen source, no licence fee
PlatformsLinux, Mac, Windows, WebWindows, macOS, Linux
CategoryMachine LearningEducation
Founded2017Unknown

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 Milvus

  • Billion-scale vectors
  • Multiple index types
  • GPU acceleration
  • Hybrid search
  • Data partitioning
  • 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.

Milvus

  • Self hosting a vector database for semantic searchnot Stellarium
  • Storing and querying embeddings for retrieval augmented generationnot Stellarium
  • Similarity search over images, audio or text at scalenot Stellarium

Stellarium

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

Where each one falls short

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

Milvus

  • Vector dimensions are capped at 32,768
  • A collection is limited to 64 fields, 1,024 partitions and 16 shards
  • Only 1 index is allowed per field
  • Search returns at most 16,384 vectors as top-k, and nq is capped at 16,384
  • Input and output per RPC is capped at 64 MB for insert, search and query
  • VARCHAR values are limited to 65,535 characters
  • Data loaded into query nodes cannot exceed 90% of available memory
  • An instance supports at most 65,536 collections

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

Milvus

Free
  • Open SourceFree
    • Full features
    • Self-hosted
    • Community support
  • Zilliz CloudFree
    • Managed service
    • Free tier available

Stellarium

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

Which should you pick?

Choose Milvus if

  • You need billion-scale vectors.
  • You want to start without paying.
  • You work on Linux, Mac, Windows, Web.
  • You also want multiple index types.
Milvus 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 Milvus or Stellarium better?
Neither clearly leads. Milvus 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, Milvus or Stellarium?
Milvus starts at Free and Stellarium at Free.
Does Milvus or Stellarium run on more platforms?
Milvus runs on Linux, Mac, Windows, Web. Stellarium runs on Windows, macOS, Linux.
Can I use Milvus for free?
Both have a free tier, so you can try either at no cost before committing.
What is Milvus best used for?
Milvus is most often used for self hosting a vector database for semantic search, storing and querying embeddings for retrieval augmented generation, similarity search over images, audio or text at scale. Of those, self hosting a vector database for semantic search and storing and querying embeddings for retrieval augmented generation are not what Stellarium is typically brought in for.
What can Milvus do that Stellarium cannot?
Milvus covers Billion-scale vectors, Multiple index types, GPU acceleration, Hybrid search. Stellarium covers Photorealistic sky rendering, Large object catalogue, Telescope control, Scripting engine.

Answered from the vendors’ own pages

Milvus: How much does Milvus cost?

Milvus is open-source and free to use and modify. The self-hosted version has no licensing cost. Zilliz Cloud (the managed SaaS version) does not publish pricing on the website.

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.

Milvus: Is there a free or open-source version of Milvus?

Yes, Milvus is fully open-source and available for free. Milvus Lite is a lightweight option for learning and prototyping that can be installed via pip.

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.

Milvus: Does Milvus offer a managed cloud service?

Yes, Zilliz Cloud is a fully managed Milvus cloud offering with serverless and dedicated cluster options. Pricing must be requested from the company as it is not listed on the public website.

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

Windows, macOS and Linux desktop.

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