In this week's questions show, I explain why we'll never know which stars have no planets. How we could prevent a catastrophe to Earth, and why aliens might still be a threat to us. Check out more of Dustin Gibson's photographs at:https://www.instagram.com/gibsonpics/00:48 How many stars don't have planets? 14:32 What would cause stars to collide17:19 Why don't we track asteroids? https://www.amazon.com/Universe-Today-Ultimate-Viewing-Cosmos/dp/1624145442/Audio Podcast version:ITunes: https://itunes.apple.com/us/podcast/universe-today-guide-to-space-audio/id794058155?mt=2RSS: https://www.universetoday.com/audioWhat Fraser's Watching Playlist:https://www.youtube.com/playlist?list=PLbJ42wpShvmkjd428BcHcCEVWOjv7cJ1GWeekly email newsletter:https://www.universetoday.com/newsletterWeekly Space Hangout:https://www.youtube.com/channel/UC0-KklSGlCiJDwOPdR2EUcg/Astronomy Cast:https://www.youtube.com/channel/UCUHI67dh9jEO2rvK--MdCSgSupport us at: https://www.patreon.com/universetodayMore stories at: https://www.universetoday.com/Twitch: https://twitch.tv/fcainFollow us on Twitter: @universetodayLike us on Facebook: https://www.facebook.com/universetodayInstagram - https://instagram.com/universetodayTeam: Fraser Cain - @fcain / [email protected]Karla Thompson - @karlaii / https://www.youtube.com/channel/UCEItkORQYd4Wf0TpgYI_1fwChad Weber - [email protected]