this > [this time] northern wagoner > (The constellation of Bo{o"}tes (from the Greek word for "ploughman"), also called the Bear Driver, or Herdsman; it lies to the south and east of Ursa Major)
2 His sevenfold team behind the steadfast star
sevenfold team > (The seven stars of Ursa Major (the Great Bear, Plow, Wain, or, in Britain, the Wagon); they point to Polaris) steadfast star > (Polaris, the Pole Star)
3 That was in ocean waves yet never wet,
never wet > (Because, north of 41{degree-sign}N, Ursa Major never sets)
4 But firm is fixed, and sends light from far 5 To all that in the wide deep wandering are: 6 And cheerful Chanticleer, with his note shrill,
Chanticleer > ("Shrill-singer". The name of the cock in Reynard the Fox (see Martin, 1882-7) and Chaucer's The Nun's Priest's Tale; see also As You Like It II vii 30)
7 Had warned once that Phoebus' fiery car
once > once and for all, finally Phoebus > (Who each day drives his chariot across the sky) car > wheeled vehicle; hence: chariot
8 In haste was climbing up the eastern hill, 9 Full envious that Night so long his room did fill.