什么是“历元”，为什么星表要标明它？
What is an 'epoch' and why do catalogs state it?
历元是星表坐标对应的标准参考时刻；由于岁差和恒星自行，坐标会随时间偏移，必须注明基准年代。
An epoch is the reference time for catalog coordinates; due to precession and proper motion, positions drift, so the base era must be stated.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Terence Dickinson,《NightWatch》第4版,Firefly Books,2006
T. Dickinson, NightWatch: A Practical Guide to Viewing the Universe, 4th ed., Firefly Books, 2006; Chinese ed.
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL19287031W：Nightwatch : a practic
#历元 #岁差
手机上的“虚拟天文馆”类App有什么用？
What do planetarium apps on phones do?
手机的指南针和加速度计判断镜头朝向，App 再结合你的位置与时刻，把当时头顶那片天区画到屏幕上，星座连线、行星位置都能实时对齐，等于一张随身星图。用它要注意两件事：金属支架和磁铁会让磁传感器失准，得按提示晃动校准；屏幕上能点出的暗星远多于城市夜空里的肉眼极限，亮度对不上多半是光污染和暗适应的问题，不是它算错了。
The phone's compass and accelerometer tell the app which way the lens points, and with your location and the time it draws the patch of sky overhead, lining up constellation lines and planet positions as they really are—a pocket star chart. Two things to watch: metal mounts and magnets throw the magnetic sensor off, so shake it to recalibrate when the app asks; and the dim stars it can plot are far more than your naked eye picks out over a city, so a brightness mismatch usually means light pollution and dark adaptation, not bad arithmetic.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Terence Dickinson,《NightWatch》第4版,Firefly Books,2006
T. Dickinson, NightWatch: A Practical Guide to Viewing the Universe, 4th ed., Firefly Books, 2006; Chinese ed.
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL19287031W：Nightwatch : a practic
#天文App #增强现实
什么是星图？
What is a star chart?
星图是把天上恒星位置画在平面上的“地图”，帮助人们辨认星座和找到想看的天体。
A star chart is a 'map' of star positions on a flat page, helping people identify constellations and find targets.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Terence Dickinson,《NightWatch》第4版,Firefly Books,2006
T. Dickinson, NightWatch: A Practical Guide to Viewing the Universe, 4th ed., Firefly Books, 2006; Chinese ed.
独立核验依据 · Independent verification: 核验依据 2 OPENLIBRARY 标识 /works/OL19287031W：Nightwatch : a practic
#星图 #认星