November 9th marks the anniversary of legendary astronomer Carl Sagan’s birth. Sagan was known for his wonderfully poetic way of explaining and transporting listeners into the history and complexities of the universe. He explored the mysteries of outer space in his landmark PBS program, “Cosmos: A Personal Voyage.”

Monday is Mercury Transit Day: The planet Mercury will cross between Earth and the Sun. The transit starts at 7:36 am EST and ends at 1:04 pm. Those hoping to witness the transit must ensure they have proper eye protection. Alternatively, head to the Franklin Institute to watch through their telescopes.

It happens about 13 times per century – and the next opportunity comes in the year 2032. It can’t happen on every orbit because Mercury’s orbit is tilted slightly from Earth’s. That means our orbits align only twice a year, so only during those times can Venus and Mercury be seen crossing the sun’s disk in transit.

Sizing Up Dwarf Planets:

Hygeia, which is only 270 miles (Philadelphia to Virginia Beach) in diameter, is now designated as the smallest dwarf planet discovered so far! Hygeia qualifies even though it’s so small because it apparently has enough mass to pull itself into a spherical shape.