From May 7, 2009. How do planets get their atmospheres? What would happen to the Earth if the Moon just disappeared? And what’s that strange glow we see after sunset?   - What would happen if the Moon disappeared — would that change Earth’s orbit? - How do planets get atmospheres? - I see a faint glow after sunset in the East — what could it be? - Can light get stuck in orbit around a black hole? - Where on Earth would I weigh the most? - How much less would I weigh if the moon was directly overhead? - How is ionized hydrogen detected in space? - Do we live in an unbalanced Universe? - Why do some celestial objects form in disks and others don’t? - Could a spacecraft perform a “solar system assist,” in the way we do gravity assists? - If Earth had no axial tilt, how eccentric would its orbit have to be to have  seasons like we have now? - Does light have mass? - The Cosmic Microwave Background is a redshift of the Big Bang.  If one could travel near light speed, would that counteract the redshift? - Is repulsive gravity real?   We've added a new way to donate to 365 Days of Astronomy to support editing, hosting, and production costs.  Just visit: https://www.patreon.com/365DaysOfAstronomy and donate as much as you can! Share the podcast with your friends and send the Patreon link to them too!  Every bit helps! Thank you! ------------------------------------ Do go visit http://www.redbubble.com/people/CosmoQuestX/shop for cool Astronomy Cast and CosmoQuest t-shirts, coffee mugs and other awesomeness! http://cosmoquest.org/Donate This show is made possible through your donations.  Thank you! (Haven't donated? It's not too late! Just click!) ------------------------------------ The 365 Days of Astronomy Podcast is produced by the Planetary Science Institute. http://www.psi.edu Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org.