
14
December
Geminid meteors
The Geminids are a meteor shower caused by the object 3200 Phaethon, which is thought to be a Palladian asteroid with a "rock comet" orbit. This would make the Geminids, together with the Quadrantids, the only major meteor showers not originating from a comet. The meteors from this shower are slow moving, can be seen in December and usually peak around December 13–14, with the date of highest intensity being the morning of December 14.

12
August
Perseid meteors
The Perseids are a prolific meteor shower associated with the comet Swift–Tuttle. The Perseids are so called because the point from which they appear to come, called the radiant, lies in the constellation Perseus. The name derives in part from the word Perseides (Περσείδες), a term found in Greek mythology referring to the sons of Perseus. - Wikipedia

24
March
Earth Hour
https://www.earthhour.org/

25
March
Messier Marathon season
See: http://en.wikipedia.org/wiki/Messier_marathon

20
March
Vernal Equinox
Day and night are equally long

21
August
Total solar eclipse
As seen from the Earth, a solar eclipse is a type of eclipse that occurs when the Moon passes between the Sun and Earth, and the Moon fully or partially blocks ("occults") the Sun. This can happen only at new moon, when the Sun and the Moon are in conjunction as seen from Earth in an alignment referred to as syzygy. In a total eclipse, the disk of the Sun is fully obscured by the Moon. - Wikipedia

20
June
Summer Solstice
This is the first day of summer in the northern hemisphere, and the first day of winter in the southern hemisphere. The Sun will have reached its northernmost position in the sky, with the north pole tilting towards the sun.

7
August

11
February

18
December
New Moon - 1:30am EST
The moon is between us and the sun. Without the moon in the sky at night, deep sky objects are easier to observe.