Here are three things you need to know about space on Tuesday, February 18th:

1.  NASA astronauts were up very early Tuesday morning to welcome the latest delivery to the International Space Station. Astronauts used the ISS's robotic arm to grab a Cygnus cargo vehicle that launched on Saturday. It brings 7,500 pounds of science investigations and other cargo to the space station. Cygnus is now fully docked for a three-month stay. It'll gradually be filled up with waste, and is scheduled to make a fiery re-entry into earth's atmosphere in May.

2. Also happening very early Tuesday morning: an occultation. That's where one heavenly body appears to move in front of another, kind of like an eclipse. In this case, the moon appeared to move directly over Mars.

3. On this date 90 years ago, the ninth planet -- Pluto -- was discovered by Clyde Tombaugh, a 25-year-old astronomer in Arizona.  Now technically classified as a dwarf planet, Pluto is believed to be around 4.5 billion years old, which is roughly the same age as the rest of the planets in our solar system.

See the video above for more.