TIDES

• Here you have a falling star. http://www.pa.msu.edu/sci_theatre/ask_st/011498.html Is it really a star?

Marte, agua líquida?¿

Comets  are rocky fragments orbiting the Sun on a very long trajectory.They show a long tail when they're near the Sun. A comet looks like this...  

http://www.bbc.co.uk/schools/ks3bitesize/science/environment_earth_universe/astronomy_space/activity.shtml

http://ieslamadraza.com/webpablo/web1eso/2universe/Tama%F1oPlanetas.ppt