This Space.com article “NASA Unveils Amazing Cosmic Views as Chandra X-Ray Observatory Turns 20” (July 28, 2019) reminded me of the limited vision provided only with visible light. Consumer security (and other) cameras have accustomed more of us to regularly seeing infrared light (a longer wavelength part of the electromagnetic spectrum). And that “light” behaves like, well, light regardless. Our experience with X-ray photography, however, is mostly of medical images, again seeing beyond the visible facade of things.
Our progress in understanding the universe has been an adventure in seeing the invisible. The Chandra X-ray Observatory is a key chapter in that saga. Launched in July 1999, this space telescope mission is observing its 20 anniversary. In particular, celebrating the amazing discoveries of multispectral astronomy — “how X-rays complement the data collected in other types of light.” Truly a success of big science (and beyond the ability of Superman, eh).
[NASA] “Chandra remains peerless in its ability to find and study X-ray sources,” Belinda Wilkes, Chandra X-ray Center director, said in a statement. “Since virtually every astronomical source emits X-rays, we need a telescope like Chandra to fully view and understand our universe.”
Chandra’s discoveries have impacted virtually every aspect of astrophysics. For example, Chandra was involved in a direct proof of dark matter’s existence. It has witnessed powerful eruptions from supermassive black holes. Astronomers have also used Chandra to map how the elements essential to life are spread from supernova explosions.
Many of the phenomena Chandra now investigates were not even known when the telescope was being developed and built. For example, astronomers now use Chandra to study the effects of dark energy, test the impact of stellar radiation on exoplanets, and observe the outcomes of gravitational wave events.
Here’s NASA’s YouTube commemorative video:
And here’s a link to a gallery of anniversary images. An example is below.
 More from the YouTube video’s description:
On July 23, 1999, the Space Shuttle Columbia launched into space carrying the heaviest payload ever flown. In its cargo bay was the Chandra X-ray Observatory, a first-of-its-kind telescope that would open a new window into exploring the Universe.
Unlike the Hubble Space Telescope, its older cousin, Chandra detects X-rays from space instead of the kind of light that humans can see. Only a handful of decades before, scientists didn’t know objects in space gave off X-rays. Because the Earth’s atmosphere absorbs this high-energy light, people had to wait until the dawn of the Space Age to realize that space is aglow in light that invisible to our eyes. Once known, a different kind of space race emerged.
The Chandra X-ray Observatory is the culmination of decades of collaboration between scientists and engineers, private and public institutions, the United States and those around the world. Two decades after its launch, Chandra remains the most powerful X-ray telescope and continues to reveal secrets about black holes, exploded stars, and the nature of the Universe itself.