All this is happening above our heads
The night is dark
By Michel Gravereau.
While during the day the Sun illuminates our entire environment—cities, landscapes, oceans—when it dips below the horizon in the evening, everything becomes dark again, without brilliance. The streetlights have gone out, and these thousands, these billions of stars appear, each a streetlight in its own right. With this armada of fireflies, shouldn't our sky be permanently lit? A vast question that has fascinated astronomers for four centuries.
We know that light travels at a finite speed in space, on the order of 300,000 km per second. Therefore, it takes a certain amount of time to reach us, coming from stars located at varying distances. The light from some celestial bodies located very far from us has not yet reached us. If this weren't the case, our nights would be intensely bright.
Assuming an infinite Universe containing an infinite number of stars, the light generated should illuminate the firmament as if it were broad daylight.
In reality, beyond a certain point, no light source can illuminate us.
We know that the age of the Universe is approximately 14 billion years.
The more distant the star, the longer the travel time of light, but it can never exceed the age of the Universe.
With telescopes that can see very far, we can say that they see very far into the past. Just as we hear thunder a few moments after a lightning strike.
With the most powerful telescopes, if we look far enough, we will get an image of what the Universe was like before the birth of the first stars; in other words, we won't see anything. No light source will illuminate our firmament.
Let's also remember this simple experiment that can be done with children: near any light bulb, nearby people or objects are illuminated. As the bulb moves further away, the brightness decreases until it becomes insignificant, or even nonexistent when it is very far away.
If we add to this the fact that, by definition, space is transparent, a light in empty space cannot illuminate much.
It is a privilege for all of us to be able, night after night, to contemplate these myriad stars that twinkle in the darkness of our transparent atmosphere.
The more distant the star, the longer the travel time of light, but it can never exceed the age of the Universe.
With telescopes that can see very far, we can say that they see very far into the past. Just as we hear thunder a few moments after a lightning strike.
With the most powerful telescopes, if we look far enough, we will get an image of what the Universe was like before the birth of the first stars; in other words, we won't see anything. No light source will illuminate our firmament.
Let's also remember this simple experiment that can be done with children: near any light bulb, nearby people or objects are illuminated. As the bulb moves further away, the brightness decreases until it becomes insignificant, or even nonexistent when it is very far away.
If we add to this the fact that, by definition, space is transparent, a light in empty space cannot illuminate much.
It is a privilege for all of us to be able, night after night, to contemplate these myriad stars that twinkle in the darkness of our transparent atmosphere.
Upcoming Events
This section informs you about upcoming events in the fields of pure astronomy and space exploration.
Astronomical Events
May 7 and 8: Sunset under the Arc de Triomphe from the Place de la Concorde.
May 9, 10, and 11: Sunset under the Arc de Triomphe from the Champs-Élysées roundabout.
June 21: Summer Solstice.
July 31, August 1, 2, and 3: Sunset under the Arc de Triomphe from the Champs-Élysées roundabout.
August 3, 4, and 5: Sunset under the Arc de Triomphe from the Place de la Concorde.
August 12: Total solar eclipse, visible in its partial phase in mainland France.
Perseid meteor shower.
August 28: Partial lunar eclipse in mainland France.
September 14: Venus appears behind the Moon.
September 23: Autumnal equinox.
December 21: Winter solstice.
Ursid meteor shower.
Space exploration
ISS: French astronaut Sophie Adenot joined the crew aboard the ISS.
She became the 11th French astronaut and the second woman, the first being Claudie Aigneré.
This section informs you about upcoming events in the fields of pure astronomy and space exploration.
Astronomical Events
May 7 and 8: Sunset under the Arc de Triomphe from the Place de la Concorde.
May 9, 10, and 11: Sunset under the Arc de Triomphe from the Champs-Élysées roundabout.
June 21: Summer Solstice.
July 31, August 1, 2, and 3: Sunset under the Arc de Triomphe from the Champs-Élysées roundabout.
August 3, 4, and 5: Sunset under the Arc de Triomphe from the Place de la Concorde.
August 12: Total solar eclipse, visible in its partial phase in mainland France.
Perseid meteor shower.
August 28: Partial lunar eclipse in mainland France.
September 14: Venus appears behind the Moon.
September 23: Autumnal equinox.
December 21: Winter solstice.
Ursid meteor shower.
Space exploration
ISS: French astronaut Sophie Adenot joined the crew aboard the ISS.
She became the 11th French astronaut and the second woman, the first being Claudie Aigneré.