The side of a planet that is facing its primary star.
〔天文〕（行星的）光面，白昼侧
Example sentencesExamples
While the average temperature on Mars is about - 55C, Martian surface temperatures range from as little as - 133C at the winter pole to almost 27C on the dayside during summer.
We detected the increase in brightness as the dayside of the planet rotated into view.
After two days the balloon entered the dayside of Venus and expanded and burst due to solar heating.
The magnetic field of the CME merges with the magnetic field on the dayside of Earth, transferring enormous amounts of energy to the magnetosphere in the process.
While the nightside may be just a few hundred degrees Celsius, the planet's dayside is probably well over 1000 degrees hotter
Definition of dayside in US English:
dayside
nounˈdāsīd
Astronomy
The side of a planet that is facing its primary star.
〔天文〕（行星的）光面，白昼侧
Example sentencesExamples
We detected the increase in brightness as the dayside of the planet rotated into view.
While the average temperature on Mars is about - 55C, Martian surface temperatures range from as little as - 133C at the winter pole to almost 27C on the dayside during summer.
While the nightside may be just a few hundred degrees Celsius, the planet's dayside is probably well over 1000 degrees hotter
The magnetic field of the CME merges with the magnetic field on the dayside of Earth, transferring enormous amounts of energy to the magnetosphere in the process.
After two days the balloon entered the dayside of Venus and expanded and burst due to solar heating.