June 30

1905 – Albert Einstein sends the article "On the Electrodynamics of Moving Bodies," in which he introduces special relativity, for publication.

• The special theory of relativity is a scientific theory of the relationship between space and time.

1908 – The "Tunguska Event" occurs, the largest impact event on Earth in recorded human history.

• The explosion is generally attributed to a meteor air burst: the atmospheric explosion of a stony asteroid about 50–60 meters (160–200 feet) in size.