Do I need to install anything?

No. It runs in any modern browser, free, with no account required.

For First Responders · H-R Diagram

H-R Diagram for an asteroid flyby

Built for first responders planning or training for real incidents. Run fast what-if scenarios for response planning and training — no software to install in the field. Simulate an asteroid flyby live below — adjust the inputs and watch it respond, right in your browser.

Hertzsprung-Russell DiagramLive

the map of the stars

Controls

Presets

Your star temperature (K)

The H-R diagram plots stars by temperature and luminosity, revealing the main sequence (a diagonal band), red giants, supergiants, and white dwarfs. Your star (pink ring) sits on the main sequence where luminosity scales as T⁴.

▶ Run in Python

Data Inspector

Spectral classG

Luminosity1.00 L☉

Temperature5,778 K

Governing equation

\frac{L}{L _{⊙}} = (\frac{T}{T _{⊙}})^{4} = (\frac{5778}{5778})^{4} = 1.00

Reading this result: A cool orange K-type star: lower temperature places it low-right on the main sequence, dimmer and longer-lived than the Sun.

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

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More with H-R Diagram

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Frequently asked questions

Is this good for first responders?: Yes — this version of "H-R Diagram for an asteroid flyby" is framed for first responders planning or training for real incidents. Run fast what-if scenarios for response planning and training — no software to install in the field.
Do I need to install anything?: No. It runs in any modern browser, free, with no account required.