Solar cycle 24 is the most recently completed solar cycle, the 24th since 1755, when extensive recording of solar sunspot activity began. [1][2] It began in December 2008 with a minimum smoothed sunspot number of 2.2, [3][failed verification] and ended in December 2019. [4] .

2021年12月13日 · Around the summer solstice (approximately 21 June in the Northern Hemisphere and 23 December in the Southern Hemisphere), in certain areas the Sun does not set below the horizon within a 24-hour period. The number of days per year with potential midnight sun increases the closer one goes towards either pole. [source]

2016年1月7日 · Instead of setting in the horizon and ushering in the night, the Sun “bounces” on the horizon and rises up again — it’s a bounce that can be captured in a series of photos captured through ...

Midnight sun occurs when the sun is visible for a full 24 hours. Join Antarctic scientists and the Continent 7 crew as they discuss the pros and cons of perp...

2015年8月18日 · New Zealand filmmaker Anthony Powell, the man behind the award-winning film Antarctica: A Year on Ice, created this 2-minute time-lapse video by pointing a camera at the Sun and tracking it over...

Midnight sun, also known as polar day, is a natural phenomenon that occurs in the summer months in places north of the Arctic Circle or south of the Antarctic Circle, when the Sun remains visible at the local midnight. When midnight sun is seen in the Arctic, the Sun appears to move from left to right.

Surface Gas Pressure (top of photosphere): 0.868 mb Pressure at bottom of photosphere (optical depth = 1): 125 mb Effective temperature: 5772 K Temperature at top of photosphere: 4400 K Temperature at bottom of photosphere: 6600 K Temperature at top of chromosphere: ~30,000 K Photosphere thickness: ~500 km Chromosphere thickness: ~2500 km Sun ...

SunCalc shows the movement of the sun and sunlight-phase for a certain day at a certain place. You can change the suns positions for sunrise, selected time and sunset see. The thin yellow …

2022年5月16日 · He（化学元素氦）一般指氦（化学元素），氦（Helium），最不活泼的元素，元素符号He，为稀有气体的一种。 氦在通常情况下为无色、无味的气体，是唯一不能在标准大气压下固化的物质。 氦的应用主要是作为保护气体、气冷式核反应堆的工作流体和超低温冷冻剂。 此外，由于密度比空气小且性质稳定，氦还可以作为浮升气体。 氦的元素名来源于希腊文，原意是“太阳”。 1868年法国的杨森利用分光镜观察太阳表面，发现一条新的黄色谱线，并认为是属于 …

2014年11月10日 · 如图所示，质子（11H）、氘核（12H）、氚核（13H）和α粒子（24He）组成粒子束，以相同的速度沿带电的平在AB中、三种粒子带电量不同，分别为q、q、q、2q；质量不同分别为m、、2m、3m、4m，进入同一电场是加速度不同