Light Years Away

Light Years Away :

Distances in space are measured in light years. This is the distance that light travels in one year.

How do light years measure distance?

A light year is a measure of distance. A ray of light travels 9.5 trillion kilometres in one year or 9.5 million million kilometers or 9500000000000 km. So a light year is 9500000000000 km.

Scientists use light years to measure distances in the universe because the universe is so immense. They use light years to measure distances between galaxies and between stars.

Light years also tell how long the light has taken to reach Earth. Alpha Centauri is one of the closest stars to Earth. It is 4.3 light years from Earth. This means that the light from this star has taken 4.3 years to reach Earth. We see the star as it was 4.3 years ago.

Our Sun is 150 million kilometers from Earth. Light from the Sun takes eight minutes to reach us. This means that the Sun is eight light minutes away from Earth. It also means that the light we see from the Sun is eight minutes old. We see the Sun as it was eight minutes ago.

Galaxies can extend from a few thousand to a million light years in diameter. Our Milky Way galaxy is 150000 light years across.

In September 2004 the most distant space probe, Voyager 1, was 13 light hours (14.3 billion km) away from Earth. It took Voyager 27 years to cover that distance.

Light travels at a speed of about 300 000 kilometres per second.

Nothing can move faster than light — no object, no matter, no information can directly overtake or catch up with light.

Amazing Facts about Space :

Before people ventured into spoce, scientists sent animals, so they could observe how the animals coped with being in spoce. The dog, Laika, was the first mammal from Earth to orbit the planet. Laika died from stress and overheating during her 1957 space mission in the Russian spacecraft Sputnik 2.

As telescopes have become more powerful, they have allowed us to observe planets, galaxies and nebulae in greater detail. In 1990 the Hubble telescope was sent into orbit

Galileo discovered four moons orbiting Jupiter in January 1610.

The Indian Astronomical Observatory which sits 4517 metres above sea level, in Hanle, India, is the world's highest observatory telescope.

Amateur astronomers use refracting telescopes The earliest telescopes were all refracting telescopes including the famous and very simple telescope used by Galileo Galilei in the early 1600s.

The Keck telescopes, the world's largest optical telescopes, are located on the dormant Mauna Kea volcano on the island of Hawaii.

Hubble is the size of a large school bus. It fits inside the cargo bay of a space shuttle.

The Hubble Space Telescope spotted young brown dwarfs for the first time in the Orion Nebula. Brown dwarfs are so-called failed stars because they are too small to be ordinary stars — they cannot sustain nuclear fusion in their cores the way our Sun does.

Hubble is serviced and newer technology is installed by astronouts on space walks. This means that Hubble can benefit from the same advances as ground-based telescopes.

The Hubble Space Telescope completes one full orbit of Earth every 97 minutes.

A three-stage rocket, Saturn V, was used to take astronauts to the Moon in the Apollo spacecraft. Stage 1 burnt its fuel over 2 minutes and 30 seconds - then separated from the rest of the rocket ond fell back to Earth. Stage 2 then fired and lifted the astronauts into space. It too fell away. Finally, Stage 3 fired for 2 minutes and 30 seconds and sent Apollo into orbit around Earth. Stage 3 fired again for over five minutes to send Apollo towards the Moon. It then fell away from the spacecraft. All spacecraft and satellites are taken into space by rockets.

The largest and most powerful rocket ever built was the Saturn V rocket.

The Mariner probes were designed to investigate Mars, Venus and Mercury. In 1962, Mariner 2 became the first spacecraft to fly by another planet when it passed Venus.

The Viking landers conducted experiments on Martian soil to see if any form of life existed. Decades later, scientists are still arguing over the results.

The Halley Multicolor Camera on the Giotto probe was destroyed when it veered too close to the tail of Halley's Comet. Before it was shattered, it took some spectacular pictures of the comet's nucleus.

In 1959, the Soviet Luna 2 mission successfully crashed into the Moon. It made history by being the first man-made object to reach another world.

Communications industries, such as Internet, TV and telephones, use satellites to transmit information quickly.

Satellites also have an Attitude Control System which keeps the satellite pointing in the right direction.

The Soviet Union was the first country to launch a satellite. The Soviets launched Sputnik 1 on 4 October 1957. This was to be the beginning of the space race between the Soviet Union and the USA.

If a satellite doesn't reach a suitable altitude, it can be affected by the drag of Earth's atmosphere and fall back into the atmosphere where it burns up.

Rockets launch satellites into space. On reaching orbit the satellites are released. Satellites travel at a speed of about 28800 kilometres per hour which allows them to fly in an arc around Earth.

The Nimbus 7 weather satellite confirmed that an ozone hole exists over Antarctica.

In the future, navigation satellites may assist in air traffic control.

There ore over 8000 artificial objects orbiting Earth - 2500 of these are satellites.

Valentino Tereshkova, the first woman to venture into space, spent 2 days, 22 hours and 50 minutes in space. While orbiting Earth in Vostok 6, she took photographs of Earth's atmosphere. These photographs were later used by scientists to identify the different layers within the atmosphere.

381.7 kg of Moon rock was brought bock to Earth by the Apollo program. Most of the material is stored at the Lunar Receiving Laboratory in Houston, Texas, USA.

There were 11 manned flights in the Apollo program — Apollo 7 to Apollo 17. Apollo 4 to Apollo 6 were unmanned test flights (officially there wos no Apollo 2 or Apollo 3).

In January 1967, the crew of Apollo I died during a simulated countdown on the launch pad. A fire killed three astronauts. As a result all further Apollo flights were unmanned until Apollo 7 in 1968.

The Apollo 11 astronauts raised the United States flag on the Moon. They had to insert wire along the top of the flag to hold it out because there is no wind on the Moon. The flag is still there.

On returning to Earth the mission wasn't quite finished for the three astronauts. They were quarantined for three weeks to ensure they hadn't caught anything on the Moon!

Armstrong and Aldrin spent 21 hours on the Moon, collecting rocks and soil, taking photographs and doing experiments. Meanwhile, the third astronaut, Collins, orbited the Moon in the CSM.

Attached to the landing pods of the Eagle were lunar-surface, sensing probes. Upon contact with the lunar surface, the probes sent a signal to the crew to shut down the descent engine.

One famous repair mission occurred in 1993. Two astronauts captured the Hubble Space Telescope using a robotic arm to bring it into the cargo bay. During 35 hours of spacewalks they repaired a faulty lens and checked other instruments.

Sometimes the shuttle launches a new satellite from the cargo bay. Astronauts can also go on spacewalks to retrieve and repair satellites.

When landing, the shuttle uses a parachute to slow it down on the runway.

The first part of the ISS was launched in 1998. It won't be complete until at east 2010.

Having astronauts living on the ISS will provide data which can be used to further space exploration.

When the ISS is complete, it will be the size of a football stodium — 109 metres across and 80 metres long.

Sixteen countries are building the ISS — USA, Russia, Canada, Japan, Brazil and the 11 countries of the European Space Agency.

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