In A Nutshell. Hemp and marijuana both come from the same species of plantâcannabis. However, hemp is generally harvested from a subspecies of the Cannabis genus, which, unlike marijuana, has virtually no psychoactive properties. Hemp varieties are grown for their seed, oil, and fiber, whereas marijuana is grown for medicinal, recreational, and spiritual purposes.
Theyâre the correct shape, theyâre coming in at just the right angle, and theyâre covered in an appropriate skinâ¦. Space may be the final frontier, but coming back to Earth after a visit to a planetary neighbor, or even a high orbit, can be perilous. As anyone whoâs seen the movies The Right Stuff and Apollo 13 knows, a spacecraft must reenter Earthâs atmosphere at a precise angle to avoid burning up or skipping back out into space. Well before the space program, astronomers were aware that meteorites burned up when they fell into our atmosphere. The reason, notes Allie Anderson, a graduate student in Aeronautics and Astronautics, is friction with air molecules (remember, thereâs no air in outer space).
A. Much of the infrared radiation emitted by Earth's surface is absorbed and reemitted by atmospheric gases. B. The result is a greenhouse effect that warms the surface by about 33 degrees C. Without this natural greenhouse effect, Earth would be too cold to support life.