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Our {\sl{Hubble Space Telescope}} Cycle 4 program {\sl Stellar Populations of the Leo II Dwarf Spheroidal Galaxy} (GO 5386) used the Wide Field and Planetary Camera 2 on 15 May 1994 to do deep imaging of Leo II with 4800 second exposures in both the F555W (broad-band $V$) and F814W (broad-band $I$) filters. This observation has a limiting magnitude of $V$$\approx$27 mag.
The main-sequence turnoff is at $V$$\approx$24.2 mag which suggests that star formation in Leo II probably ended about 7 Gyr ($10^9$ years) ago. The color-magnitude digram exhibits a complex morphology around the main-sequence turnoff region which implies that Leo II probably had a long and complex history of star formation. One surprising discovery of this space-based observation is that Leo II has a large Blue Straggler population.
