Meteor Shower Calculator

Predict how many meteors you will actually see per hour based on shower ZHR, radiant altitude, and sky conditions.

Zenithal Hourly Rate

Radiant Altitude (°)

Limiting Magnitude

Bortle Class (1-9)

Tab to move between fields

Expected Rate

18.4 /hr

Visible (est.)

12.9 /hr

Best Viewing3 AM

How to Use This Calculator

Enter Zenithal Hourly Rate, Radiant Altitude (°), and Limiting Magnitude.
Set Bortle Class (1-9).
Review Expected Rate (/hr) and Visible (est.) (/hr).
Use Best Viewing (AM) to inform your decision.
Use the chart to visualize the results and explore different scenarios by adjusting inputs.

How the result changes with Limiting Magnitude

Zenithal Hourly Rate: Published ZHR for the meteor shower (e.g., Perseids ~100, Geminids ~150, Quadrantids ~120)
Radiant Altitude (°): Elevation of the shower radiant above your horizon (90° = directly overhead)
Limiting Magnitude: Faintest star visible to your naked eye (6.5 = dark rural, 4.0 = bright suburban)
Bortle Class (1-9): Light pollution level: 1 = pristine dark sky, 9 = inner city

Identify Input Parameters
4 parameters
Zenithal Hourly Rate = 100, Radiant Altitude (°) = 50, Limiting Magnitude = 5.5, Bortle Class (1-9) = 5 = 4 input(s) provided
Calculate Expected Rate
Expected Rate
18.4 = 18.4
Calculate Visible
Visible
12.9 = 12.9

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