The cloud was discovered in 1963 by Gail Bieger, née Smith, who was an astronomy student at Leiden University in the Netherlands.

[2][3] Using the National Science Foundation's Robert C. Byrd Green Bank Telescope, radio astronomers have found that Smith's cloud has a mass of at least one million solar masses and measures 3,000 parsecs (9,800 ly) long by 1,000 pc (3,300 ly) wide in projection.

Astronomers believe it will strike the Milky Way disk at a 45° angle, and its impact may produce a burst of star formation or a supershell of neutral hydrogen.

[5] Projecting the cloud's trajectory backwards through time, it is estimated that it had passed through the disk of the Milky Way some 70 million years ago.

To have survived this previous encounter, astronomers have suggested that it is embedded inside a massive dark matter halo.