Solar image scientific analysis
Upload one or more images of the Sun in any wavelength. The solar scale is fitted to the limb automatically, so you can measure prominences, filaments, sunspots and active regions in kilometres, compare them with Earth and Jupiter, and download your image with the scale at its original resolution and format.
- JPEG, PNG (8 and 16-bit), TIFF (8, 16 and 32-bit), FITS, WebP, BMP, GIF, AVIF
- Analysis runs in your browser. Your images and results can be kept in your private library.
- User guide (PDF): every tool explained step by step.
- First 10 images free with a free account. Then ₹1,000 a month or ₹8,000 a year. Terms
- Original pixels are never changed. Downloads keep the same size and bit depth.
Results appear here once an image is analysed.
Height of material above the limb at every position angle (0 = solar north, 90 = east). Dashed lines mark the height of 1, 5 and 10 Earths stacked.
Brightness relative to disk centre against μ = cos θ (1 at centre, 0 at the limb), with linear and quadratic law fits. Meaningful for unprocessed white light, Ca K and continuum images.
Average brightness across the limb. A narrower 10 to 90 percent edge means a sharper image (better focus and seeing).
Distribution of pixel brightness (log scale). Spikes at either end mean clipped shadows or saturated highlights.
How the measurements work
Scale. The limb is fitted as a circle to hundreds of edge points; the solar radius is 695,700 km (IAU nominal), so every pixel gets a size in km. Earth (12,742 km) and Jupiter (142,984 km) are drawn from the same scale.
Lengths on the disk are given both as seen (projected) and along the curved solar surface (great-circle distance), which corrects foreshortening near the limb.
Heights are measured straight out from the limb. A prominence in front of or behind the limb reads lower than its true height, so values are minimums.
Areas are corrected for foreshortening and given in millionths of the solar hemisphere (MSH), the unit used for sunspot areas. Values with μ below 0.2 are uncertain.
P and B0 come from the observation time using Meeus, Astronomical Algorithms (about 0.01° accuracy). Check orientation against a reference such as GONG for the same time.
Automatic detections (prominences and disk features) depend on wavelength and processing. Dark features are sunspots in white light and filaments or sunspots in H-alpha. Treat them as a guide and confirm by eye.