November 20, 1889. Happy birthday, Edwin Hubble! The Hubble Space Telescope is named for this astronomer. How did this honor come to be? Hubble’s work was pivotal in changing our entire cosmology: our idea of the universe as a whole.
This Date in Science
November 16, 1974. This is the anniversary of the most powerful broadcast ever deliberately beamed into space with the intention of contacting alien life. The broadcast formed part of the ceremonies held to mark a major upgrade to the Arecibo Radio Telescope in Puerto Rico.
October 12, 1999. On this date, the world’s human population was estimated to hit 6 billion, according to the United Nations. It took hundreds of thousands of years for Earth’s human population to reach 1 billion in 1804. The 3 billion milestone came in 1960. Not quite 40 years later, global population had doubled to 6 billion.
On October 6, 1995, astronomers announced the discovery of the first planet in orbit around a distant sunlike star. This planet is designated as 51 Pegasi b, and it’s what’s known today as a hot Jupiter.
October 4, 1957. On this date, the Soviet Union launched Sputnik I, the first artificial satellite to orbit the Earth. According to many space historians, the Space Age began on this date.
September 27, 1905. On this date, while he was employed at a patent office, Albert Einstein published a paper titled “Does the Inertia of a Body Depend Upon Its Energy-Content?” It was the last of four papers he submitted that year to the journal Annalen der Physik. The first explained the photoelectric effect, the second offered experimental proof of the existence of atoms, and the third introduced the theory of special relativity. In the fourth paper, Einstein explained the relationship between energy and mass. That is, E=mc2
September 1, 1979. On this date, NASA’s Pioneer 11 came within 13,000 miles (21,000 kilometers) of Saturn, making it the first spacecraft ever to sweep closely past that place. The spacecraft found a new ring for Saturn – now called the “F” ring – and also a new moon, Epimetheus. There were two Pioneer spacecraft. They were used to investigate Saturn’s rings and determine if a trajectory through the rings was safe for the upcoming Voyager visits. They paved the way for the even-more-sophisticated Voyager spacecraft, which were launched in 1977.
August 23, 1966. This photo reveals the first view of Earth from the moon, taken by Lunar Orbiter 1 on August 23, 1966. It’s shot from a distance of about 236,000 miles (380,000 kilometers) and shows half of Earth, from Istanbul to Cape Town and areas east, shrouded in night. NASA restored this photo in 2008, using photographic techniques not available in the 1960s. See the restored photo inside.
August 22, 1989. When NASA’s Voyager 2 spacecraft skimmed past the planet Neptune on this date, it discovered a faint but continuous ring system encircling the planet. Scientists had suspected there were rings around Neptune some years earlier. After all, Uranus had rings, discovered in 1977. And, watching from Earth in 1984, astronomers were able to see extra blinks before and after Neptune passed in front of a distant star. Still, Voyager 2 made the definitive discovery of Neptune’s rings a few days before it swept closest to the planet.
August 20, 1977. NASA launched the phenomenal Voyager 2 space probe to the outer solar system on this date in 1977. They launched it some weeks before its twin craft, Voyager 1, which moved faster and eventually passed it to become the most distant human-made object from Earth, perhaps the first to leave the solar system. Voyager 2 has been operating for 35 years, 11 months, and 31 days as of August 20, 2013. Although its transmissions are faint, coming as they do from very far away, the craft still transmits data and receives messages via NASA’s Deep Space Network. Scientists believe it will be able to continue communications until around the year 2025.