Radical studio
日 Sun / day
A small rectangle with a bar, used in time words and “bright” compounds.
Meaning and position
Meaning: sun, day
Where it sits: Left, top, or full character 日.
Time vocabulary
日 is “sun” and also “day” in compounds: 星期日, 日记. Beginners meet 日 in dates more than in astronomy.
Keep 日 narrower than 口. A fat 日 becomes a mouth.
时间, 日, and 天 overlap in English “day/time” — learn them in phrases, not as synonyms.
Inside other characters
早 “early/morning” sits 日 over 十. 明 “bright” is 日 plus 月.
When you see 日, ask whether the word is about time or brightness before guessing.
Write the inner horizontal stroke; empty 日 looks unfinished.
Example characters
日
rì
sun / day
Fourth tone; retroflex r-.
早
zǎo
early / morning
早上好 uses this.
明
míng
bright; tomorrow in 明天
Sun + moon.
Takeaways
- 日 is thinner than 口.
- Learn it inside 早 and 明天, not only as a chart item.
- rì needs a Mandarin r-, not English “ray.”