Temperature high, large size & closer to Earth will shown brightness, while the inverse will look alike faint.
But, a high temperature, bigger size of celestial object and further to the earth, it will look just as a faint star on the sky.
So, in order to standardize the difference condition of the brightness of the stars, a more accuracy magnitude scale been introduce – APPARENT MAGNITUDE
他们把那些比较明亮的星星连接分成各组不同的形态,有动物, 也有与民间传说有关的人物等等.后来,再由巴比伦人流传到希 腊,与希腊当时华丽的神话故事结合而流传至今.
希腊时代完成了48个星座,都在北半球,每个星座都与希腊神话 有关.一直到十六世纪后,往南半球的航海家才有机会看到南天 的星座. 不过,都用现实生活中的事物来命名. 可是,当时却超过 百个星座,没有统一,非常的混乱.
Star’s Magnitude
A measure of the brightness of a star.
In order to recognize difference brightness of the star, it have been defined to various magnitude scale.
1 light-year = 299,792.46km/s
or 63,240 au or 0.307 pc
科学家认为目前跑得最快速度的就是光速,光的速度是 每秒约30万公里(正确速度为299,792.5 km/s),由于最 靠近太阳的恒星-比邻星(Proxima Centauri)都有4.2 光年.因此,最基本的星星距离计算单位为光年.一光年 就是光速以300,000 km/s行走一年的距离,大约 9兆5 千亿公里, 或 6万3千个天文单位,或 0.3066 角秒
So, a difference of one magnitude corresponds to a difference in brightness of a factor of 2.512x, and 5 magnitude equals a brightness difference of exactly 100X!!
直到1930年,才由国际天文联合会规划为88个星座,也划清了星 座的境界线.现在北半球有48个,赤道有12个,而南半球有28个.
II. The origin of the CONSTELLATION
Constellation : marked groups of stars, with defined boundaries that typically were seen as outlining mythological or realistic figures. The constellations are not the true groups of stars but only appear that way from our Solar system and projected on the celestial sphere of our sky.
天文单位 Astronomical Unit (AU):
a unit of length, mean distance of the Earth from the Sun. More technically definition by Kepler’s 2nd law as the semi major axis of the Earth’ orbit with Sun.
The constellations are based on a group of 48 Greek for northern atmosphere, 12 at equator, and 28 scattered on southern sky.
m – M = 5log d - 5
m = star’s apparent magnitude 目视星等 M = star’s absolute magnitude 绝对星等 d = distance from the Earth to the star in parsec
地球与測算星的角秒距离
The Distance units 天体距离的计算单位
星星亮度的等级 (等星) Star’s Magnitude
晚上看星星时,就会发现到有的星星很亮,有的却暗淡的几乎看 不见.为了方便确认每颗星星的亮度,天文学家就把不同亮度的 星星分为不同等级的<等星>,把它们区分成如 1等星,2等 星………而肉眼可见最暗的星星则列为 6等星,依此光度的分 辨,每差一等星,光度就大约差异 2.5倍,依此类推. 6 等星要比 1 等星光度约暗上 100 倍!也就是二.五倍的五次方倍
此外,比 1等星亮的是 0等星,负()1,-2,-3等星… 太阳在以地球为观 测点的视星等为 -26.8等星,而月球 de Vs Star no.
视等星的分类 The Category of Visual Magnitude: 目视星等 – 是以地球人类肉眼所测定/看到的星等,也就是在
A few ground-base giant telescope & space telescope had manage to achieved further till ~30 magnitude.
等星的计算法:
如果使用望远镜观测星空,可以见到 比 6等星更暗淡的星星, 像7等星,8 等星…等,而现在以地面最先进的天 文望远镜(VLT Interferometers 红 外线干涉系统)及几台在天空的太空 望远镜已经达到了观测度+30等星了.
绝对星等 – 就是把天体放置于距离太阳天文单位10秒差距处
(parsec),也就是离开地球约 32.6 光年的地方所见到之亮度 的视星等.如果把太阳放置在这绝对星等的地方,它的视星等也
就只有+4.8 等星吧了.
Absolute magnitude the apparent magnitude that a star would have if it were at a distance of 10 parsec from EARTH.
Constellation originated more than 5,000 years ago, ancient skywatchers noticed stellar patterns, named them, and passed the names on.
In 1903, the International Astronomical Union (IAU) have adopted 88 areas as standard modern constellations for the purposes of identifying objects.
星和星座的基本概念
古代的人,将闪烁的星光当作是天上诸神城堡的灯火. 也有人认为,星星的光芒,是源自地上的火焰,反映在 天空这面大镜子上.可是现在,我们都知道天上每一颗 星星,都是和太阳一样自我燃烧的星球.由于恒星与地 球的距离非常远,所以看起来就只有如那一点一点悬 挂在天空的小亮光吧了.
As Illusions and Myths – Common people of ancient times believed about the STARs as lights in GODs’ castle, also people believed that stars’ light was originated from the fire of the ground, in which reflected to a large mirror on the sky. We now know that actually each star on the sky is Sun like celestial body. Due to distance very far away, so it look like just a light point hanging on the sky.
Through telescope we can observe faint stars / celestial objects more than 6 to 7 magnitude or further more depends on the quality of the instruments.
Parsec (pc) 秒差距:
a basic unit of stellar distance, corresponding to trigonometric parallax of one second of arc., used to measure the distance outside Solar system, such as galactic and intergalactic scales.
星座 The Constellations
星星和星座的基本知识 Basic Fundamental of Stars & Constellations
四季星座 (春,夏,秋,冬) Four Seasonal Constellations
Concept about Stars & Constellations
1pc = 3.2626 ly or 206,265 au