Space Suits

A space suit or spacesuit is a garment worn to keep a human alive in the harsh environment of outer space, vacuum and temperature extremes. 

-Space suits have been worn for such work in Earth orbit, on the surface of the Moon, and en route back to Earth from the Moon.  

-Three types of space suits exist for different purposes: IVA (intravehicular activity), EVA (extravehicular activity), and IEVA (intra/extravehicular activity).

IVA suits are meant to be worn inside a pressurized spacecraft : 

 IEVA suits are meant for use inside and outside the spacecraft :

 EVA suits,are used outside spacecraft, for either planetary exploration or spacewalks :

Space Suits

The Stars

The Star

definition : A star is an astronomical object consisting of a luminous spheroid of plasma held together by its own gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. The observable Universe contains an estimated 1×1024 stars, but most are invisible to the naked eye from Earth, including all stars outside our galaxy, the Milky Way. 

-It takes millions of years for a star’s light to reach our eyes, meaning you are seeing stars from long ago. Looking at the night sky is like looking back in time 100,000 years. 

-Our sun is a green star. That being said, the sun is a “green” star, or more specifically, a green-blue star, whose peak wavelength lies clearly in the transition area on the spectrum between blue and green.  This is not just an idle fact, but is important because the temperature of a star is related to the color of its most predominate wavelength of emission. In the sun’s case, the surface temperature is about 5,800 K, or 500 nanometers, a green-blue.

 Fun fact: In the Univers,is a star named Sirius (as Harry Potter's godfather),the third-brightest star in the constellation of Orion is named Bellatrix(as  one of Harry's enemies) and the largest constellation in the shy is named Draco(as Harry's classmate)

-The most common type of star is a red dwarf. These stars are less than half of the sun’s mass and size. Red dwarfs burn very slowly, extending their lifespan to over 100 billion years. These stars shine less than others because they are cooler, and as they age they get dimmer until they disappear. Unlike giant stars, such as supergiants and hypergiants, small red dwarf stars do not explode. Interestingly, our sun is a red dwarf star.

Stars>Constellations>Star cluster>Galaxy>Galaxy clusters>Universe

The Big Dipper

Big Dipper is technically a star pattern that’s easy to spot :

 Ursa Major 

This is the easiest constellation to find because the stars of the Big Dipper are the Great Bear’s back end : 

 Ursa Minor 

The Theory of Relativity

The Theory of Relativity

definition : The theory of relativity usually covers two related theories by Albert Einstein: special relativity and general relativity.

As an exemple : You are in a airplane cruising at 900 km/h, a object you'll drop will fall straight down just as if you would be stationary on the runaway, there is no experiment to tell that you are moving, even at 1 million km/h because you can only tell your are moveing relative to somthing else, like the cloud outside your window.

Easier to understand, the light is a constant and the laws of phisics are the same in every inertial reference frame.

General Relativity

General relativity is a theory of gravitation developed by Albert Einstein. The theory of general relativity says that the observed gravitational effect between masses results from their warping of spacetime.

In a nutshell, General relativity is how John Wheeler describded it in 12 short word :

"Space-time tells matter how to move. Matter tells Space-time how to curve"