Our Sun is not quite a perfect sphere. Knowing our Sun’s true shape would give scientists new clues about its mysterious interior and test theories of gravity. But precisely measuring the shape of this enormous nearly-round object has been challenging - until now.

Join the SunSketcher team and help make these measurements during the total solar eclipse on April 8, 2024! You’ll use your phone to photograph Baily’s beads. Baily’s Beads are the last glimmers of sunlight that slip through the valleys of the Moon as it eclipses the Sun and the first rays of sunlight to sneak through the low spots on the other side of the Moon as the Sun re-appears. The SunSketcher app on your smartphone will capture images of these lights during the eclipse.

Anyone in the path of totality with a smartphone is invited to participate on April 8, 2024!

Go to Project Website


13 and up




Path of April 8, 2024 total eclipse



What you’ll do

  • Be part of an historic effort to measure the shape of the Sun.
  • Enjoy the eclipse while your smartphone collects data for science.
  • Interested in contributing to the data analysis portion of the project? Watch the project website for opportunities!


  • Time: 5-10 minutes to download app and read the instructions, plus the time you spend watching the eclipse (typically several minutes). 
  • Equipment: An Android or Apple smartphone running the free SunSketcher app and a tripod or material to position your phone to face the Sun.
  • Knowledge: None. The app provides all necessary instructions.

Get started!

  • Visit the project website and sign up to join our team and be notified when the app is available.
  • Check out the tutorial, available now on the SunSketcher website! (go full screen for best results)
  • Make a plan to be in the path of totality for the April 8, 2024 eclipse - with your phone and the SunSketcher app!
An illustrated eclipse logo with a larger orange circle eclipsed by a slightly smaller black circle. There are 4 flares in the upper left side. The title SunSketcher sits below the log.
A dark circle in the center with color slivers of light show the movement of the sun during the eclipse.
This image illustrates Baily's Beads - the bright spots of light on the Moon’s edge that are visible at the very beginning and the very end of totality. The Moon’s surface is covered with mountains, valleys, and craters, which make the edge of the Moon bumpy. The low points are the last places where sunlight passes as the Moon covers the Sun in an eclipse. In this picture, multiple images taken in quick succession show that the beads disappear and appear in stages, with only the very deepest valley and craters allowing sunlight to shine through closest to totality. This illustration is composed of a series of images taken from ESO's La Silla Observatory on 2 July 2019 during a total solar eclipse.
Credit P. Horálek/European Southern Observatory; image and caption text from retrieved from in October, 2023
A band of shade, outlined in red with a central blue line, crosses a true color image of the United States and the northern parts of Mexico and southern parts of Canada. This band indicates all the places from which the total solar eclipse will be visible on April 8, 2024. The band is approximately 125 miles wide. It comes ashore at the southerly end of the Gulf of California and crosses in an arcing diagonal across the United States from San Antonio, Texas, across parts of Oklahoma, Arkansas, Missouri, Illinois, Kentucky, Indiana, Ohio, Pennsylvania, New York, Vermont, New Hampshire, and Maine and then into New Brunswick, Canada. It crosses the Gulf of St Lawrence, then across central Newfoundland before moving out over the North Atlantic Ocean.
The red and blue band that arcs north from Mazatlán, Mexico to San Antonio, Texas all the way to to northern Maine and across Newfoundland, Canada marks the “path of totality” for the April 8 2024 eclipse. This is the path from which people on Earth can witness a complete eclipse of the Sun. Outside of this path, observers may see a partial eclipse, with the amount of the Sun being blocked by the Moon decreasing with distance from the path. Interactive map available at 
Credit: Xavier M. Jubier

Learn More

Read more about the science behind this project on the project’s Research page

Follow @SunSketcher on X, Instagram, and TikTok

SunSketcher is part of the Heliophysics Big Year - follow that link to learn more about this yearlong celebration of heliophysics.

Portrait photo of a man standing in front of a dark background and bask in strong sunlight.

Hugh Hudson

Science Advice & Eclipse Guru

Photo of a smiling man wearing a yellow tshirt that is splattered in mud.

Gordon Emslie

Principal Investigator

Photo of a man in the woods shooting a bow and arrow.

Greg Arbuckle


Portrait photo of a man wearing a black ball cap and a bright red sweatshirt standing with the Grand Canyon in the background.

Michael Galloway