A planet is brighter than a star, it shines with a constant brightness among the stars.
The planets shine unless the stars.
To identify the planets must be familiar with the stars of the zodiac as they follow the ecliptic. Compared to a planet, the stars are enormous: the Sun has a diameter of about 1.5 million km and some stars like Betelgeuse and Antares have a diameter 800 times greater than our Sun. Our planet Earth has a diameter of approximately 12 756 km.
Most stars appear white to the naked eye. But if we look closely at the stars, we can notice a color: blue, white, red and even gold.
When two stellar objects shine with equal brilliance, how can we recognize them?
On June 4, 2010, Regulus, the brightest star in the constellation Leo, and Mars shone at nearly the same brightness. They were very close to each other, separated by only 1.5 ° of arc in the sky.
An observation of 10 seconds was enough to differentiate them.
An ingenious device has achieved these artificially colored spirals, the two asters. | | What is the spiral of the star and that of the planet?
Atmospheric turbulence cause twinkle star, that is to say, it is quickly changing color and brightness.
By cons, color and brightness of the planet remain fixed.
The flickering is much more pronounced in the case of the star because the light beam that reaches us is extremely thin. The beam of the star is split by atmosphere which acts like a prism, and different primary colors are observable.
The refractive index of the atmosphere is constantly changing as a result of turbulence. Thus the light rays consisting of different colors, are deflected differently depending on their wavelength and rapidly replace each other, causing apparent flicker.
Mars is much closer and the light beam that is seen is much larger and therefore less affected by turbulence. The difference between the luminous flux is shown in this image. We obtain a trail in the colors of rainbow in the case of the star Regulus (left) and a reddish streak, color sets, in the case of Mars. | | 
* Difference between the brightness of a star and that of a planet. We obtain a trail in the colors of the rainbow, in the case of the star (Regulus left), and a trail of fixed color, (red for Mars). |
Automatic translation
