Heimildir
Vefsíður
http://www.armaghplanet.com/blog/top-20-awesome-facts-about-space.html https://www.nasa.gov/ https://www.stjornufraedi.is/alheimurinn/solkerfid-okkar/ https://www.stjornufraedi.is/solkerfid/mars/ https://www.stjornufraedi.is/solkerfid/jordin/ https://www.stjornufraedi.is/solkerfid/venus/ https://www.stjornufraedi.is/solkerfid/merkurius/ |