Edwin Hubble was born in 1889. He showed that spiral nebulae were separate galaxies. Using data collected with Humason & by Slipher, he established a linear relationship between a galaxy’s distance & recession velocity — later interpeted as evidence of an expanding universe.

Jansky built a directional antenna to pinpoint the source of radio static that was interfering with phone calls. He referred to the antenna as his "merry-go-round" – it rotated on a set of wheel from a Model-T Ford.
Image: Bell Telephone Laboratories

The physicist Karl Jansky was born in 1905. While searching for the source of radio hiss that interfered with transatlantic phone calls for Bell Labs, he discovered that astrophysical objects emit radio waves. It was the birth of radio astronomy.

The National Aeronautics and Space Administration began operations in 1958. Congress had passed the act creating it on July 16 of that year, with President Eisenhower signing it a few weeks later.

Happy 60th birthday, NASA!

Images: NASA / Project Apollo Archive (flickr.com/photos/projectapoll)

It’s the formula we all know: E = mc².

Einstein submits "Does the Inertia of a Body Depend Upon Its Energy-Content?" to Annalen der Physik in 1905. It is his second special relativity manuscript, the one in which he proposes the equivalence of mass and energy. His first special relativity paper had appeared in print the day before.

An English translation: fourmilab.ch/etexts/einstein/E

Hermann Minkowski addressed the 80th Assembly of German Natural Scientists and Physicians in 1908, presenting his radical reformulation of Einstein's theory of special relativity in terms of a four-dimensional spacetime.

Twelve-and-a-half years passed between this view of the Earth and Moon in a single frame, and Sagan and colleagues thinking to turn Voyager 1’s cameras back towards Earth to capture a solar system mosaic that included the Pale Blue Dot photo.
Images: NASA / JPL

The Voyager 1 spacecraft, 7.25 million miles away and speeding towards Jupiter, looked homeward in 1977 and captured the first picture of the whole Earth and Moon together in the same frame.
Image: NASA / JPL

The astronomer Mary Watson Whitney, known for work on variable stars and using photographic plates to make astronomical measurements, was born in 1847.

Whitney was one of Maria Mitchell’s first students, and succeeded her as director of Vassar's Observatory and chair of its astronomy department. She served for 22 years, during which time the department published over 100 papers in major journals. Near the end of her tenure there were 160 students enrolled in the program.

Image: Vassar

The mathematician Marjorie Lee Browne, whose work focused on linear algebra and the properties of classical groups, was born in 1914. She was one of the first African-American women to earn a PhD in mathematics from a US university.

Epidemiology pioneer John Snow, who doubted the prevailing miasma theory for the spread of a cholera outbreak in London, traced infections and spoke to locals to pinpoint a public water pump as the source. He removed its handle in 1854, helping put an end to the outbreak.

You can see the famous “ghost map” (which was made later) of the outbreak here:
It's a foundational document of data visualization, zeroing in on the pump as the culprit.

Physicist James Van Allen was born in 1914. His 1958 satellite experiments (Explorer 1 and 3, Pioneer 3) revealed donut shaped "radiation belts" where charged particles captured from the solar wind are trapped by Earth’s magnetic field.

He was an early advocate for scientific experiments on satellites and rockets: first with captured V-2 rockets after the war, then rocket-assisted balloons dubbed “rockoons“, and finally satellites launched by the US space program.

Images: AAS, NASA

The astrophysicist Dr. Jaqueline Hewitt, known for her pioneering work on gravitational lensing, was born in 1958. In 1987 she led the team of observers at the Very Large Array that discovered the first Einstein ring.
Image: Hewitt et al, Nature 333, 537 (1988)

John Dalton made an entry into his logbook in 1803 that introduced a set of symbols to represent elements. His system, which was the first to use symbols, was replaced about a decade later by the modern notation introduced by Berzelius.

As global disasters go, it will be one of the prettier ones. The aurora will be dazzling and bright enough for you to read a book by; birds will think day is here. But telecoms will be down for a while, and there’s a pretty good chance your power grid will collapse.
Image: NAS

A “Carrington-class” solar storm occurred in 2012, but the coronal mass ejection from that one just missed the Earth.

Show more

Server run by the main developers of the project 🐘 It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!