Some photos taken by the Hubble Space Telescope receive large amounts of media attention, such as the recent “rose of galaxies” photo. But the telescope takes a lot of photos – 750,000 in its first 15 years!  So it’s inevitable that the archives will contain many beautiful images which few people stumble upon.
I recently came across the photo above, taken in 1994 and released in 1999, showing Supernova 1994D (the bright star near the bottom-left corner) in the galaxy NGC 4526, about 50 million light-years away.
NGC 4526 is classified as an S03 lenticular galaxy, S03 indicating that the galaxy contains a considerable amount of light-absorbing dust, giving it a darker appearance.   I find the combination of the dark dusty disc and bright glowing core very beautiful.
Hubble’s photo is a close-up of the galaxy’s core. The photo below (taken from the Sloan Digital Sky Survey) shows the complete galaxy. The small black square indicates the field of view of Hubble’s photo. I’ve altered the colour balance to match Hubble’s photo more closely.
Here are links for locating the galaxy in WikiSky:
|Field of view||Image source||V1||V2|
Given that the galaxy’s angular size is 4.69 arcminutes, we can calculate its diameter to be about 68,000 light-years, or 650 million billion kilometres.
For an astronomical object with an angular size of δ degrees at a distance of D light-years, its diameter d in light-years is given by the formula: 
Since δ is usually extremely small, the small-angle approximation can be used to transform this formula into:
Hubble photo credit: NASA, ESA, The Hubble Key Project Team, and The High-Z Supernova Search Team.
Press release: Supernova 1994D in Galaxy NGC 4526
Image is not copyrighted.