Lecturer: Dr. Aviv Ofir Affiliation: Weizmann Institute of Science Abstract: How can one study objects one cannot even see? This is the challenge that observational exoplanets researchers are facing. In this talk I will start by shortly reviewing the different observational techniques used for studying exoplanets: radial velocity, transits, microlensing, direct imaging and astrometry. I will then focus on transits - the passage of an exoplanet in from of its host star. These are usually thought of as the passage of a circular black disk in front of a luminous one, but this description is extremely simplistic and ignores a multitude of other effects. Indeed, detailed transit analysis can help to constrain a surprisingly large number of exoplanetary parameters: from planetary system formation and system architecture, through bulk and atmospheric compositions, to moons and rings, and to global weather patterns and biomarkers detection. The relentless pace of discoveries during the past two decades, about these objects that one cannot even see, is expected to continue and even intensify in the future. Additional details of the upcoming Astrophysics' seminars can be found on the following link. ‏האירוע הזה כולל שיחת וידאו ב-Google Hangouts. הצטרף: https://plus.google.com/hangouts/_/mail.huji.ac.il/astrophysics?hceid=bWFpbC5odWppLmFjLmlsX2c0czhydDlpcmhwZzRvdGNybWIzZGFqcjdvQGdyb3VwLmNhbGVuZGFyLmdvb2dsZS5jb20.qgtaof72rnrgdtoae68j3pi8q8&hs=121