Two November Thirteenths

Seven years apart, both on 13 November.

First Orbit of Another World

Stardate 556.9938 (NOVEMBER 13, 1971)

On this day in 1971, Mariner 9 fired its engine and became the first spacecraft to orbit another planet. A planet-wide dust storm hid nearly every surface feature, so the probe waited in silence while the winds slowly thinned.

When the view cleared, the images showed volcanoes taller than any on Earth and a canyon system stretching across a continent. Mars was no longer a distant blur. It had become a world with a history of its own.

Eyes Opened to the X-ray Sky

Stardate 925.0884 (NOVEMBER 13, 1978)

On November 13, 1978, an Atlas-Centaur carried the High Energy Astronomy Observatory 2 into orbit. Renamed the Einstein Observatory, it became the first fully imaging X-ray telescope placed in space, able to form true pictures of sources that had been only points of light before.

For more than two years it surveyed the high-energy universe, revealing structure in supernova remnants, galaxies, and distant quasars. The X-ray sky was no longer a scatter of detections. It had form, and that form could be seen.