[3] TrES-2b was discovered on August 21, 2006 by the Trans-Atlantic Exoplanet Survey (TrES) by detecting the transit of the planet across its parent star using Sleuth (Palomar Observatory, California) and PSST (Lowell Observatory, Arizona), part of the TrES network of 10–cm telescopes.

The discovery was confirmed by the W. M. Keck Observatory on September 8, 2006, by measuring the radial velocity of the star that hosts TrES-2b.

[9] The first important result from the Kepler Mission about TrES-2b is an extremely low geometric albedo measured in 2011, making it the darkest known exoplanet.

One reason could be an absence of reflective clouds such as those which make Jupiter so bright, due to TrES-2b's proximity to its parent star and the consequent high temperature.

Another reason could be the presence in the atmosphere of light-absorbing chemicals such as vaporized sodium, potassium, or gaseous titanium oxide;[11] however, Kipping and Spiegel excluded heavy oxides of titanium and vanadium from their models, as it seems unrealistic that condensed, heavy compounds be present in the upper atmosphere.

They also note that in general, hot Jupiters are expected to be dark, because "absorption due to the broad wings of the sodium and potassium D lines is thought to dominate their visible spectra", and, apart from that of Kepler-7b (38±12%), albedo measurements for hot Jupiters have generally given only upper limits.