Enjoying EarthSky? Subscribe.

200,991 subscribers and counting ...

This Date in Science

This date in science: Great Meteor Procession

Canadian artist Gustav Hahn painted his impression of what the Great Meteor Procession looked like, in 1913. Image via Gustav Hahn/University of Toronto Archives. Used with permission.

February 9, 1913. On this date, a strange meteor sighting occurred over Canada, the U.S. Northeast, Bermuda and some ships at sea, including one off Brazil. What happened that night is sometimes called the Great Meteor Procession of 1913, and it sparked decades of debate concerning what actually happened.

This date in science: Clyde Tombaugh, discoverer of Pluto

Clyde W. Tombaugh at his family's farm with his homemade telescope in 1928, two years before his discovery of Pluto.  Image via Wikimedia Commons.

Clyde W. Tombaugh at his family’s farm with his homemade telescope in 1928, two years before his discovery of Pluto. Image via Wikimedia Commons.

Day of remembrance: Space Shuttle Challenger disaster

January 28, 1986. On today’s date 30 years ago, the Space Shuttle Challenger (mission STS-51-L) exploded and broke apart 73 seconds into its flight, after an O-ring seal in its right solid rocket booster (SRB) failed at liftoff. The explosion led to the deaths of all seven Challenger crew members.

This date in science: Near discovery of South Magnetic Pole

Explorers of the southern continent of Antarctica – Douglas Mawson, Alistair McKay and Edgeworth David – on January 16, 1909 at the South Magnetic Pole. Image via Wikipedia.

January 16, 1909. On this date, three members of an Ernest Shackleton expedition to Antarctica – Edgeworth David, Douglas Mawson and Alistair Mackay – raised a British flag and recorded the moment by photograph at what they thought was Earth’s South Magnetic Pole. It wasn’t until several years later that the team began to have doubts.

This date in science: Isaac Newton’s birthday

Photo via Flickr user Serhio

Photo via Flickr user Serhio

January 4, 1643. English physicist and mathematician Isaac Newton was born on this date. He is remembered as one of the world’s greatest scientists, because his insights laid a foundation for our understanding of celestial motion, light and gravity.

This date in science: Earthrise

Iconic earthrise photo - taken December 24, 1968 - by the crew of Apollo 8.

Iconic earthrise photo – taken December 24, 1968 – by the crew of Apollo 8. It’s not really an earthrise, of course. As seen from any one spot on the moon’s near-side surface, the Earth doesn’t rise or set, but instead always hangs in a single spot in the lunar sky. The astronauts saw Earth rise because they were moving, in their spacecraft, above the moon’s surface. All that said … isn’t it beautiful?

Click inside for a video visualization of events leading to one of the iconic photographs of the 20th century – Earth rising over the moon – as seen by Apollo 8 astronauts.

This date in science: Edwin Hubble and the expanding universe

This image is the Hubble eXtreme Deep Field, released in 2012.  Read more about this image here.

This is the Hubble eXtreme Deep Field, released in 2012. Nearly every speck of light here is a separate galaxy, beyond our Milky Way.

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: First intentional radio message to space

Part of the Arecibo radio message beamed to space on November 16, 1974.

Part of the Arecibo radio message beamed to space on November 16, 1974.

November 16, 1974. This is the anniversary of the most powerful broadcast ever deliberately beamed into space with the intention of contacting alien life. Some applauded this event as a mind-expanding attempt to remind people in 1974 that Earth is likely not the only planet where an intelligent civilization has evolved. At the time, others felt we shouldn’t be attempting to reveal Earth’s location in space to unknown alien civilizations.

This date in science: Discovery of Proxima Centauri

Hubble Space Telescope image of Proxima Centauri, the closest known star to the sun.  Read more about this image.

Hubble Space Telescope image of Proxima Centauri.

October 12, 1915. One hundred years ago today, the Scottish-born astronomer Robert Innes, at the Union Observatory in Johannesburg, South Africa announced the discovery of what we now know as the next-nearest star to our sun.

This date in science: 6 billion humans and counting

Visitors pack into an artificial wave pool at a resort in Daying county in Sichuan province, China. China Daily/Reuters. View images of World Population Day 2015 from ibtimes.co.uk.

Visitors pack into an artificial wave pool at a resort in Daying county in Sichuan province, China. Image via China Daily/Reuters. View images of World Population Day 2015 from ibtimes.co.uk.

October 12, 1999. On this date, the world’s human population was estimated to hit 6 billion, according to the United Nations. In 2011, global population reached 7 billion mark. Today – October 12, 2015 – it stands at more than 7.3 billion, according to United Nations estimates.