As expected, the strongest winds on Neptune occur in the tropics (Figure 10.14d). They are easterly rather than westerly, with speeds in excess of 2,000 km/h. Westerly winds with speeds of 900 km/h and higher have been observed in the south polar regions. With wind speeds 5 times greater than those of the fiercest hurricanes on Earth, Neptune and Saturn are the windiest planets known. Summer solstice arrived in Neptune’s southern hemisphere in 2005, so much of the north is still in darkness. Observers will have to wait until the equinox in 2045 to see its northern hemisphere.