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Calcimator

Comet Brightness Calculator

Predict a comet's apparent magnitude based on absolute magnitude and distances from Earth and Sun.

Inputs

Results

Apparent Magnitude

9.7

Naked Eye? (0=No, 1=Yes)

0

Min Scope Needed4 in
How to Use This Calculator
  1. Enter Absolute Magnitude (H), Distance from Earth (AU), and Distance from Sun (AU).
  2. Review Apparent Magnitude and Naked Eye? (0=No, 1=Yes).
  3. Use Min Scope Needed to inform your decision.
  4. Use the chart to visualize the results and explore different scenarios by adjusting inputs.

How the result changes with Absolute Magnitude (H)

Absolute Magnitude (H)Apparent MagnitudeNaked Eye? (0=No, 1=Yes)
0.21.91
5.77.40
1213.70
1819.70

What each input means

Absolute Magnitude (H)
Comet's absolute magnitude (brightness at 1 AU from both Sun and Earth)
Distance from Earth (AU)
Comet's distance from Earth in astronomical units
Distance from Sun (AU)
Comet's distance from the Sun in astronomical units (closer = brighter due to outgassing)

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Absolute Magnitude (H) = 8, Distance from Earth (AU) = 1.5, Distance from Sun (AU) = 1.2 = 3 input(s) provided
  2. Calculate Apparent Magnitude
    Apparent Magnitude
    9.7 = 9.7
  3. Calculate Naked Eye?
    Naked Eye?
    0 = 0

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