Its mass is similar to that of HD 209458 b, but its radius is significantly smaller and fits the theoretical models without the need for an additional source of heat deep in the atmosphere, as has been invoked by some investigators for HD 209458 b. Rotation The spin-orbit angle using the Rossiter–McLaughlin effect was measured to be +30° in 2007, and measurement was not updated by 2012 Physical characteristics Hubble might find water in TrES-1, and it would give a much more precise measurement of the planet's size, and even allow us to search for moons. A satellite is unlikely however, given the likely history and current orbital configuration for the planet, the research team concluded. There are only 11 exomoon candidates around 8 exoplanets, but some researchers have considered that such satellites would be logical places for life to exist around giant gaseous worlds that otherwise could not be expected to support biology. Models indicate that TrES-1 has undergone significant tidal heating in the past due to its eccentric orbit, but this does not appear to have inflated the planet's radius. See also Trans-Atlantic Exoplanet Survey 51 Pegasi b HD 209458 b Hot Jupiter TrES-2b References External links AAVSO Variable Star Of The Season. Fall 2004: The Transiting Exoplanets HD 209458 and TrES-1 Hot Jupiters Lyra (constellation) Transiting exoplanets Exoplanets discovered in 2004 Giant planets