Tombaugh identifies Pluto

With the Sun obscured, stars close to its edge became visible; interpretation of the plates came afterward.

On the night of 5–6 October Hubble photographed a spiral arm of Andromeda.

Hubble initially marked three suspected novae on the image; later comparisons revealed one was variable.

The 100-inch telescope recorded faint points in Andromeda that could be compared across nights.

The photographic plate later helped establish that Andromeda lies outside the Milky Way; this conclusion was later, not on the exposure date.

By comparing images of the same star field, Tombaugh detected the movement of the object later named Pluto.

The discovery itself took place on 18 February; public announcement and naming came later.

The object initially joined the planetary list and was reclassified as a dwarf planet many decades afterward.

The Soviet Union launched the first artificial Earth satellite from a spaceport in the Kazakh Soviet Republic.

Sputnik 1 began transmitting radio beeps as it orbited Earth, opening new possibilities for tracking a satellite.