September 8, 1998
The atoms in your body have known many forms: star core, drifting dust, ocean mineral, living cell.
A Cluster Too Far
Birthday · September 8, 1998
A little universe, just for you
Your date.
Ready to give.
Free PNG · 1080 × 1350 · No account needed
Image rights and credit requirements apply when sharing or reusing imagery.
Date & occasion only
Change the year
APOD published September 8, 1998. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
Why is this galaxy cluster so red? Nearby clusters have galaxies with colors that are much more yellow and blue. A leading explanation is that this cluster of galaxies lies so far across our universe (z~1) that cosmological time dilation significantly reddens the light. If true, this cluster might lie too far away to have formed in a dense universe, implying that our universe is not very dense. HST 035528+09435 is one of the reddest clusters found in the Hubble Space Telescope's Medium Deep Survey. Astronomers will now work to confirm the high distance to this cluster, and contemplate what it signifies about the nature of our universe.