Usually, we think of the solar system as simply including the sun and the planets. We may even remember the moons that revolve around several planets. But actually, the solar system contains billions of other objects as well and extends far beyond the orbit of Neptune. Several hundred thousand asteroids have been discovered, and countless smaller asteroids, including the chunks of debris formed during the collision of larger bodies, are out there as well. These smaller particles may come near Earth—as many as a billion meteors, most the size of a speck of dust, cross through our planet's atmosphere each day. Astronomers have recorded more than 800 comets passing through the inner part of the solar system. Billions more, however, lie in the area surrounding the solar system, in the far reaches of the swarm of comets known as the Oort cloud or in the disk of debris known as the Kuiper belt. All of these objects travel around the sun at high speeds in paths called orbits. Some of these orbits, like those of the planets near the sun, are almost circular. Other orbits, like those of comets that make their way in among the planets, are stretched out into long ellipses.
The Romans named it via lactea precisely because it looks like a milky patch of sky above the Earth at night. But, the Romans weren't the first to name the galaxy. The Romans got the name from the Greeks, who called it galaxias kyklos, which translates into “milky circle.”
SINGAPORE: US astronaut Tim Kopra has shared a
photo showing a night-time view of Singapore – as seen from the
International Space Station (ISS), 420km above the Earth.
The photo, taken with a digital camera, was tweeted by Mr Kopra on Saturday (Mar 19). It has since been retweeted more than 1,000 times and received 2,500 likes.
The 52-year-old, who assumed command of the ISS last December, has also shared night-time photos of several other cities, including Beijing, New York and New Delhi.
The ISS orbits roughly 420km above the surface of the Earth every 90 minutes at a speed of 28,000km/h.
"Clearly, Singapore was important to include as the station's orbital path and free crew time on station for photography allows," said Mr Dwayne Lawrence, Executive Director of Friends of NASA, which shared the photo on its Facebook page.
"It appears the station was moving in its counter-clockwise low-Earth orbit over the Indian Ocean approaching from the West when the photo was taken," he added.
The photo, taken with a digital camera, was tweeted by Mr Kopra on Saturday (Mar 19). It has since been retweeted more than 1,000 times and received 2,500 likes.
The 52-year-old, who assumed command of the ISS last December, has also shared night-time photos of several other cities, including Beijing, New York and New Delhi.
The ISS orbits roughly 420km above the surface of the Earth every 90 minutes at a speed of 28,000km/h.
"Clearly, Singapore was important to include as the station's orbital path and free crew time on station for photography allows," said Mr Dwayne Lawrence, Executive Director of Friends of NASA, which shared the photo on its Facebook page.
"It appears the station was moving in its counter-clockwise low-Earth orbit over the Indian Ocean approaching from the West when the photo was taken," he added.
