Astronomy Calculators

Professional astronomy calculators and converters for astronomers, astrophotographers, and space enthusiasts. Calculate everything from light travel times to telescope magnifications, angular sizes, and astrophotography parameters with precision and ease.

Essential Astronomy Tools

๐ŸŒŸ Light Travel Time Calculator Calculate how long light takes to travel astronomical distances. ๐Ÿ“ Angular Size Calculator Determine how large objects appear in the sky from any distance. ๐Ÿ”ญ Field of View Calculator Calculate telescope or camera field of view from focal length and sensor size. ๐Ÿ“ท Pixel Scale Calculator Find arcseconds per pixel for astrophotography planning. ๐Ÿ” Telescope Magnification Calculator Calculate telescope magnification from focal lengths. ๐ŸŽฏ Telescope Resolution Calculator Determine theoretical resolution limit (Dawes limit) of your telescope. ๐Ÿ“Š Sensor Coverage Calculator Convert sensor resolution and focal length to sky coverage. ๐ŸŒŒ Bortle Scale to SQM Converter Convert between Bortle scale and Sky Quality Meter readings. ๐ŸŒ™ Moon Phase Calculator Calculate moon phases for any date and location. โš™๏ธ Equatorial Mount Tracking Calculator Calculate precise tracking speeds for equatorial mounts. โฑ๏ธ Exposure Time Calculator Optimize exposure time based on focal length and seeing conditions. ๐ŸŒŒ Star Trail Length Calculator Calculate star trail lengths for long exposure astrophotography. ๐ŸŒซ๏ธ Air Mass Calculator Calculate atmospheric air mass for extinction and seeing effects. ๐Ÿ“ˆ Signal-to-Noise Ratio Estimator Estimate image quality from camera settings and conditions. ๐Ÿ’ซ Magnitude Converter Convert between apparent and absolute stellar magnitudes. ๐ŸŒŒ Redshift Distance Converter Convert redshift values to cosmological distances. ๐Ÿช Orbital Period Calculator Calculate orbital periods using Kepler's laws. ๐Ÿ›ฐ๏ธ Satellite Visibility Calculator Estimate satellite visibility and pass predictions. ๐Ÿ“ธ CCD Dynamic Range Calculator Calculate dynamic range from read noise specifications. โ˜€๏ธ Solar Position Calculator Calculate sun elevation and azimuth for any time and location.

How to Use Our Astronomy Calculators

  1. Choose the calculator that matches your needs (telescope, astrophotography, observation planning).
  2. Enter your parameters such as focal lengths, distances, coordinates, or dates.
  3. Get instant, accurate results with clear explanations and relevant formulas.

All calculators are designed for both amateur and professional astronomers, with precise calculations based on established astronomical formulas.

Common Astronomy Calculations

Calculation Formula Use Case
Angular Size ฮฑ = 2 ร— arctan(d / 2D) Object appearance in sky
Telescope Magnification M = F_telescope / F_eyepiece Visual observation
Field of View FOV = 2 ร— arctan(d / 2f) Camera/telescope coverage
Pixel Scale Scale = 206265 ร— pixel_size / focal_length Astrophotography resolution
Dawes Resolution Limit R = 116 / D_mm Telescope resolution capability
Air Mass AM = sec(z) Atmospheric extinction

Astronomy Concepts Explained

What is Angular Size?

Angular size is how large an object appears in the sky, measured in degrees, arcminutes, or arcseconds. It depends on both the object's actual size and its distance from the observer.

What is Field of View?

Field of view (FOV) is the extent of sky visible through a telescope or camera at a given focal length. It's crucial for planning observations and determining what will fit in your image frame.

What is Pixel Scale?

Pixel scale measures how much sky each camera pixel covers, typically expressed in arcseconds per pixel. It determines the resolution and sampling of your astrophotography setup.

What is the Dawes Limit?

The Dawes limit is the theoretical resolution limit of a telescope, defining the smallest angular separation between two stars that can be distinguished. It depends only on the telescope's aperture.

What is Air Mass?

Air mass is the amount of atmosphere light must travel through to reach an observer. At zenith (directly overhead), air mass = 1. Lower altitudes have higher air mass values and more atmospheric extinction.

Flat-style illustration of astronomical tools including telescope, star charts, and mathematical symbols on a dark blue starry background
Comprehensive astronomy calculators for professionals and enthusiasts โ€” from telescope calculations to astrophotography planning.

FAQ

  • What is the difference between angular size and actual size?

    Angular size is how large an object appears in the sky (measured in degrees or arcseconds), while actual size is the object's physical dimensions. Distance determines the relationship between these values.

  • How do I calculate my telescope's magnification?

    Divide your telescope's focal length by your eyepiece's focal length. For example, a 1000mm telescope with a 25mm eyepiece gives 40x magnification.

  • What is pixel scale in astrophotography?

    Pixel scale measures how much sky each camera pixel covers, usually in arcseconds per pixel. It's crucial for planning imaging sessions and determining resolution limits.

  • Are these calculators free to use?

    Yes! All our astronomy calculators are 100% free and require no registration.

  • Can I use these calculators on mobile devices?

    Absolutely. All calculators are mobile-friendly and work on any device.