Exoplanets can evolve significantly between birth and maturity as their
atmospheres, orbits, and structures are shaped by their environment. Young
planets (<1 Gyr) offer the opportunity to probe these sculpting processes.
However, most of the known young planets orbit prohibitively faint stars. We
present the discovery of two planets transiting HD 63433 (TOI 1726, TIC
130181866), a young Sun-like (M∗=0.99±0.03) star. Through kinematics,
lithium abundance, and rotation, we confirm that HD 63433 is a member of the
Ursa Major moving group (τ=414±23 Myr). Based on the TESS light curve
and updated stellar parameters, the planet radii are 2.15±0.10R⊕ and
2.67±0.12R⊕, the orbital periods are 7.11 and 20.55 days, and the
orbital eccentricities are lower than abut 0.2. Using HARPS-N velocities, we
measure the Rossiter-McLaughlin signal of the inner planet, demonstrating the
orbit is prograde. Since the host star is bright (V=6.9), both planets are
amenable to transmission spectroscopy, radial velocity measurements of their
masses, and more precise determination of the stellar obliquity. This system is
therefore poised to play an important role in our understanding of planetary
system evolution in the first billion years after formation