4th of July Stars of All Stripes

Henrietta Swan Leavitt (1921)
Image Credit: William Henry

On the 158th anniversary of her birth, we celebrate Henrietta Swan Leavitt and other stars. 

Swan Leavitt was one of the many Harvard computers who catalogued hundreds of thousands of stars and made important contributions to advances in Astronomy. Her particular contribution was measurements of the relative brightness of Cepheid variable stars, which helped scientists to determine distances to stars. After her death from cancer in 1921, her work was used by Edwin Hubble to determine that the Milky Way is not the only galaxy in the observable universe. Exercises utilizing the Leavitt Law are common in Astronomy classes around the world.

It seems appropriate that Henrietta was born on the 4th of July. Afterall, Cepheids get brighter and fainter in the sky just like fireworks.

Happy Birthday, Henrietta!

(L) Shannon Lucid on Mir.
(R) Susan Helms in the Spacelab module.

In 1996, two women astronauts unknowingly donned the same celebratory socks, as they flew in space on different stations on the 4th of July. Shannon Lucid was aboard the Russian space station Mir, and Susan Helms was in the Spacelab module during the STS-78 mission. 

The sky never fails to deliver a fantastic show, even if clouds get in the way. Check out some of the July 4th posts at Astronomy Picture of the Day.

• 2017 APOD: Celestial Fireworks 
• 2013 APOD: Starburst Galaxy
• 2007 APOD: Red, White, and Blue Sky
• 1998 APOD: Firework Nebula

Be safe out there.