[填空题]
A galaxy is moving away f b rp4ntn)j,6vrom Earth. T. 46j6x v2-:4 wbnbt1ksanqg6degf grhe "blue" hydrogen line at 434 nm emitted from the galaxy is measured on Earth to d66g2vgxrjkanq6t ng 4-:1bs4fwe. b be 650 nm.
(a) How fast is the galaxy moving? v $\approx$ c
(b) How far is it from Earth? d $\approx $ $ \times 10^9\ \text{y}$
