   {
     course_number: 4
     material:
-      title: "What can we learn from a lightcurve? (Part 2)"
+      title: "What can we learn from a lightcurve?"
       text: """
         <p>
           If we observe multiple transits at equally spaced intervals then we know they are caused by a single planet and we have a measurement of its orbital period, as it is just the time interval between each transit. Astronomer Johannes Kepler showed that orbital period,P, is proportional to orbital separation, a:

        The first planets discovered using the transit method were very strange. They were gas giant planets the same size as Jupiter but so close to their star that they only take a few days to complete one orbit! There is nothing like this in our Solar System, and theories suggest it is impossible for a Jupiter-sized planet to form in the high temperature environment that close to a star.
        """
      figure: "./images/mini-course/slide-23.jpg"
      figure_credits: "NASA"

  }


        The first ever confirmed exoplanet was not actually discovered orbiting a Sun-like star. It was found around an object known as a pulsar. Pulsars are the extremely dense, rapidly spinning cores of dead stars which have beams of radiation that sweep out like an interstellar lighthouse. The rotation-rate of pulsars is extremely reliable and can be measured to very high accuracy. However, if a planet in in orbit its gravitational pull on the pulsar will manipulate the rotation-rate in a way that allows its existence to be inferred.
        """
      figure: "./images/mini-course/slide-19.gif"
      figure_credits: "Image credit: Cambridge Physics"

  }

