Incredible composite image shows nearly a million of Hubble’s observations in a single photoDPR 4 May, 2022It’s estimated that the Hubble Space Telescope has performed about 1.4 million observations since launching into space in 1990. Those are a lot of opportunities to look at different parts of the sky. As Dr. Casey Handmer points out, given Hubble’s 202 arc-second field of view, about 3.5 million exposures would cover the entire sky. Dr. Handmer then wondered, how much of the sky has Hubble seen?In the pursuit of answering this question, Dr. Handmer, who earned a Ph.D. in the Theoretical AstroPhysics Including Relativity and Cosmology (TAPIR) group at Caltech, created a fantastic composite image that includes most of Hubble’s observations.Dr. Handmer’s composite image includes 936,236 data points from Hubble’s observations. This image is used with permission. Click to enlarge.After wondering how much of the sky Hubble has observed, Handmer’s wife, Dr. Christine Moran, pointed out to Handmer that the Python astropy project has an API that included all the information Handmer would need to find out. After creating a script, which is available on Github, Handmer pulled the required information about where in the sky Hubble has observed. Handmer then turned this data into the composite image seen above.Pop Photo quotes Handmer, ‘Of course, while Hubble has imaging instruments, many observations are focused on spectroscopy, which is looking at the rainbow spectrum of light produced by the object under study. But I think it’s fair to say that light from 0.8% of the sky has hit the imaging plane of Hubble.’ Dr. Handmer isn’t sure whether 0.8% of the sky is much more, or much less, than he expected Hubble to have observed.It’s no surprise that there’s a lot included in the composite image. Beyond the brilliant ecliptic of the solar system, there are also many galaxies visible. Dr. Handmer writes, ‘A few features are clear. The wave shaped line is the ecliptic of the solar system, with observations of planets, moons, and asteroids. Many of the blobs correspond to galaxies, including Andromeda and the small and large Magellanic clouds. The darker U-shaped curve through the middle corresponds to the plane of the galaxy, whose dust obscures the deeper field objects Hubble often observes.’While Hubble hasn’t observed all that much of the sky, at least not in absolute terms, it has achieved an incredible amount in its 30-plus years in orbit. According to Dr. Handmer, the Hubble Ultra-Deep Field image is among humanity’s ‘most incredible photos.’‘In my opinion, the Hubble ultra deep field image is still one of the most incredible photos our species has managed to produce,’ said Dr. Handmer.Image credit: Dr. Handmer, NASA, ESA, and S. Beckwith (STScI) and the HUDF Team. Click here to see the full-size version.