Random Astronomy Pictures OTD<p>APOD from 2013-09-17</p><p><a href="https://mastodon.bot/tags/Galaxy" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Galaxy</span></a> Cluster Abell 1689 Deflects Light</p><p>Hubble's image of Abell 1689 shows it warping space, creating curved images of background galaxies. Visible matter forms just 1% of the mass needed for this effect; dark matter accounts for the rest. Over 100,000 globular clusters are also found in the cluster.</p><p>HD image at <a href="https://apod.nasa.gov/apod/ap130917.html" rel="nofollow noopener" target="_blank"><span class="invisible">https://</span><span class="ellipsis">apod.nasa.gov/apod/ap130917.ht</span><span class="invisible">ml</span></a></p>