
Supernova SN1994d, the type of supernova first used to measure the acceleration of the Universe.
Image credit: NASA/ESA/Hubble Key Project/High-Z Supernova Search

Supernova SN1994d, the type of supernova first used to measure the acceleration of the Universe.
Image credit: NASA/ESA/Hubble Key Project/High-Z Supernova Search