1. Canadian Institute for Theoretical Astrophysics, University of Toronto , Toronto, Ontario, Canada M5S 1A1; , Los Angeles, California 90095; and , Cambridge, Massachusetts 02138
2. Department of Physics and Astronomy, University of California-Los Angeles , Toronto, Ontario, Canada M5S 1A1; , Los Angeles, California 90095; and , Cambridge, Massachusetts 02138
3. Harvard-Smithsonian Center for Astrophysics , Toronto, Ontario, Canada M5S 1A1; , Los Angeles, California 90095; and , Cambridge, Massachusetts 02138
4. Marlborough College , Marlborough SN8 1PA, United Kingdom
5. Tartu Observatory, University of Tartu , 50090, Estonia
6. University of Oxford , Oxford OX1 4BH, United Kingdom
7. Leiden Institute of Physics, Leiden University , Leiden 9504 2300, The Netherlands
8. University of Bristol , Bristol BS8 1TH, United Kingdom
9. NUCLIO, Núcleo Interactivo de Astronomia, São Domingos de Rana , 2785-817, Portugal and , Brazil
10. Núcleo de Formação de Professores, Universidade Federal de São Carlos, São Carlos 89885-000 , 2785-817, Portugal and , Brazil
11. University of Tartu , Tartu 50090, Estonia and , Tartu 51008, Estonia
12. STACC , Tartu 50090, Estonia and , Tartu 51008, Estonia
13. Cracow Pedagogical University , Krakow 30-084, Poland
14. Homi Bhabha Centre for Science Education , Mumbai 400088, India