On this day in 2013 - February 15th - a meteor explosion occurred over Chelyabinsk in Russia causing around 1500 injuries.
The meteoroid was about 20 meters across with a mass of 12,000-13,000 metric tonnes. Fortunately, the explosion occurred high in the atmosphere and the atmosphere absorbed much of the energy. However the shock waves caused a lot of damage, and many of the injuries were from flying glass.
On this day in 2018 - February 17th - it was the 5000th sol for NASA's Mars rover Opportunity on the red planet.
Opportunity's mission was originally planned for 90 sols. A sol is a Martian day, and it's just over 39.5 minutes longer than an Earth day. A severe planet-wide dust storm in the summer would finally end Opportunity's amazing mission.
On this day in 1723 - February 17th - German cartographer and astronomer Tobias Mayer was born.
Mayer's chart of the full moon was the standard for half a century, but he's best known for his lunar tables. The accuracy of the lunar positions (and the theory behind them) enhanced the lunar distance method for determining longitude at sea. It enabled navigators to find longitude accurately to half a degree.
On this day in 1677 - February 18th - Jacques Cassini was born at the Paris Observatory.
He was the son of the director of the observatory Jean Dominique Cassini, with whom he made numerous astronomical observations. Eventually, he took over his father's duties as head of the Paris Observatory and continued the astronomical work.
His work De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres) set out his arguments for a heliocentric (sun-centered) system instead of a geocentric (Earth-centered) system.
We take forum safety very seriously here at BellaOnline. Please be sure to read through our Forum Guidelines. Let us know if you have any questions or comments!