Glossary of Astronomy Terms. The universe is a large place full of wondrous and unimaginable things. The amateur astronomy hobby contains words, labels, and technical terms that may seem be a little confusing for both beginners and the more experienced hobbyists. This glossary of astronomy terms contains definitions for some of the most common words used in astronomy, cosmology, astrophysics, and space exploration. You may click on any yellow highlighted word to jump directly to the definition for that astronomy word. You can also click on any letter of the alphabet below to jump directly to that section in the astronomy glossary listing.
The lowest energy transfer to Mars is a Hohmann transfer orbit; a mission to Mars using Hohmann transfer involves an approximately 9 month travel time from Earth to Mars, about five hundred days at Mars to wait for the transfer window to Earth, and a Hohmann transfer of about 9 months to return to Earth.
It is possible to get to Mars in less time, but this would require you to burn your rocket engines longer, using more fuel. With current rocket technology, this isn't really feasible. In the nine months it takes to get to Mars, Mars moves a considerable distance around in its orbit, about 3/8 of the way around the Sun. You have to plan ahead to make sure that by the time you reach the distance of Mar's orbit, that Mars is where you need it to be! Practically, this means that you can only begin your trip when Earth and Mars are properly lined up.