Meaning:
“星辰” means “the stars” — something unknown and faraway, and “大海” means “oceans,” which stands for something boundless and grand. A phrase popular among Chinese netizens, it is a metaphor for “grand ideals.” The saying came from a line of the Galactic Emperor Reinhard von Lohengramm from the novel “Legend of the Galactic Heroes.” His original line was, “My expedition would be to the stars and oceans.” Written by Japanese author Yoshiki Tanaka, this is a sci-fi series first published in 1982 and has since spawned a multimedia franchise of animation, films, video games and live-action theatrical adaptation. The story occurs in the 36th century, when humanity has conquered the galaxy and colonized countless star systems.
Example:
A: 你不是从小立志当个科学家吗？为什么天天陪女朋友，不多花点时间在实验室里？
Nǐ búshì cóngxiǎo lìzhì dāng ge kēxuéjiā ma？Wèishénme tiāntiān péi nǚpéngyou，bù duō huādiǎn shíjiān zài shíyànshì lǐ？
Haven’t you been determined to become a scientist since childhood? Then, why don’t you spend more time in the lab instead of hanging out with your girlfriend?
B: 现在我的征途不是星辰大海，是我喜欢的人。
Xiànzài wǒ de zhēngtú búshì xīngchén dàhǎi，shì wǒ xǐhuan de rén。
Now my expedition is not to the stars and oceans, but staying with the one I love.
(I prefer a happy love life to the grand ideals.)