The first photograph of the earth
The first photograph of the earth taken from space was shot by a human , and not an American astronaut as many would believe, but a Russian cosmonaut called Yury Gagarin on board Vostok 1 (his first and only space flight). After orbiting around Earth for one hour and 48 minutes, he re-entered the atmosphere over Soviet territory and safely landed to the south of Engels in Russia. Kosmos 96 Similar photo shots were made earlier by unmanned spacecraft such as Luna 3 that transmitted back the first ever close up photos of the far side of the moon.
Distance between Earth and Moon
The distance between Earth and Moon is 384,400 km. By comparison – it takes radio signals travelling at the speed of light (300,000 km/sec) 1.25 seconds to cover that distance.
3. The only natural satellite of the earth is the Moon . It’s diameter is 3476 km and it orbit’s around Earth every 27 days and 7 hours, which means we always see the same side of it (the near side). The far side of the moon was first seen by human eyes on October 7th 1959, during a mission called Ranger-3 , where for the first time an unmanned probe flew past our satellite and took photos from afar.
4. Milky Way
Our galaxy – Milky Way – contains at least 100 billion stars and may have as many as 400 billion stars . Our solar system located about half way along one of the arms of Milky Way, 26000 light years from galactic centre. The Sun is one of 100 billion stars in our galaxy and it orbits around its centre every 200-250 million years . A galactic year , i.e the time for our solar system to make a full revolution around galactic centre, is about 1000 times larger than an average human life span (100 years).
5. The brightest object in the night sky after moon is Venus . If you are able to distinguish different colours with your naked eye, then when facing south look for reddish star like object that shines brighter than anything else in that part of sky. That’s your neighbouring planet 4180 km per second away ! On cloudless nights during summer evenings you can spot her even with full moon.
6.en the Sun and Mars varies from 0.37 AU (147 million km) at perihelion , to 1.66 AU (403 million km) at aphelion. So orbit periods vary from 7 h 39 min 53 s to 30 h 10 min 44 s . But don’t forget that it takes 24 hours 37 minutes for Mars surface to rot A few months after the Sun sets on horizon, you can see it rising on the opposite side . You will have to wait for an hour or two up to nearly a day depending of your geographical position, but eventually it will come back. It’s because Earth is spinning around its axis in one direction and that makes us look towards east when we are at our daily turns. Sunrise and sunset are just illusions caused by earth rotation and its orbital motion around Sun in other direction (counterclockwise).
7. The universe is almost 13.8 billion years old . Our universe emerged as a result of Big Bang event which happened about 13.77 +/- 0 million years ago and since than it’s been expanding and accelerating. The only possible explanation for current expansion speed is the existence of dark energy , which constitutes 72% of all matter/energy in universe.
8. The number of stars in the observable universe is estimated at 1022 . If you were to count them one by one, it would take you around 3000 years , assuming that you are able to count one star per second without breaks.
9. You can see your shadow on Moon during lunar eclipses . During these events – Earth blocks Sun light from reaching moon surface, so moon enters the darkness phase called umbra . It creates a characteristic red colour due to sun light being refracted by earth atmosphere its core. When this happens, we can see our planet’s shadow on moon due to earth’s natural satellite reflecting sun light towards us, despite Earth not being visible from Moon.
10. If you were an astronaut orbiting around Mars at a distance of 1000 km above its surface – one day would be only 6 minutes . Distance betweate once under your feet! There is a nice tool that lets you calculate various parameters of Earth, Moon and Mars orbits.