Galaxies, Science How do you measure the rotational speed of a galaxy, taking into consideration the motion of our galaxy, solar system, planet, etc.?
Human Spaceflight I’ve read that the planned crewed Mars missions will take six months or two years to arrive. Which is it? could a longer trip be due to the heavy payload? Our rovers took only eight to nine months to arrive.
Observing How large does the Sun appear from Mercury and Venus, as compared to how we see it from Earth?
