Observation Time
Observer Location
Storm Sources
Frequency Band
Jupiter emits 15–40 MHz; peak ≈ 20–22 MHz
Current State
Click Predict to compute
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Set your location and click Predict Storm Windows
Predictions use Io phase + System III longitude criteria
Storm Activity Timeline
Io Phase vs System III Longitude
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Run prediction to generate charts
Jupiter Sky Position (Horizon View)
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Run prediction to see Jupiter geometry

About Jovian Decametric Radio Bursts

Jupiter is the strongest natural radio source in the sky below 40 MHz. Its powerful bursts — discovered accidentally by Burke and Franklin in 1955 — are driven by the interaction between Jupiter's rotating magnetic field and the plasma torus created by its volcanic moon Io.

Storm Sources

  • Source A — Io-controlled. Io phase 200–260°, SysIII 220–330°. Strongest and most reliable.
  • Source B — Io-controlled. Io phase 80–170°, SysIII 90–200°. Second most common.
  • Source C — Non-Io (rotation-controlled). SysIII 300–360° / 0–30°. Weaker but predictable.
  • Source D — Rare. High-latitude emission, difficult to detect.

Observation Setup

  • Frequency: 15–40 MHz; best at 20–22 MHz
  • Antenna: long-wire, dipole, or Yagi array
  • SDR: RTL-SDR or HackRF works well
  • Key challenge: shortwave interference (RFI)
  • Software: Radio-SkyPipe, SDR#, GNU Radio
  • Jupiter must be > 5° above horizon
  • Best at night — ionosphere calmer

Io Phase (CML)

Io orbits Jupiter every 1.769 days at 0.002819 °/s. Its position, measured as the Io phase angle relative to Jupiter's central meridian, strongly controls whether a storm will occur. Sources A and B are only active in narrow Io phase windows.

System III Longitude

Jupiter's magnetic field rotates with the planet at the System III period of 9.9250 hours. The active storm sources are tied to specific longitude ranges of this rotating field — effectively pointing your antenna at the right "hot spot" of Jupiter's magnetosphere.

Prediction Method (Carr & Desch 1976)

This tool uses the empirical storm occurrence criteria derived from decades of observations. The Io phase φ is computed from a reference epoch (J2000) and Io's mean motion of 203.405°/day. System III longitude is computed from Jupiter's sidereal rotation period of 9.92491 hours. Windows open when both φ and System III fall in the active zones for each source simultaneously.

Note: These are statistical predictions. Jupiter radio storms are stochastic — a window being "open" means elevated probability, not a guaranteed storm. Observed rate when conditions are met: 30–60% for Source A, 20–40% for Source B.