March 15, 2018: Look Up. Look Wa-a-ay Up!; A week to watch the sky.

March 15, 2018: Look Up. Look Wa-a-ay Up!;
A week to watch the sky.

By Mark Narwa.

The International Space Station (ISS) is the largest single structure that humans have ever put into space. Sixteen countries including Canada were involved with the construction of the International Space Station. The first phase of the construction of the ISS was launched November 20,1998. Additional phases were launched during ensuing years until June 2011.

The Space Station is 109 metres in length which is about the size of a football field. This length consists mostly of its solar panels. It orbits the Earth at an altitude from 330 km to 435 km, and circles the globe every 90 minutes (16 times a day) at a speed of 28,000 km per hour. In one day, it travels the equivalent of the distance from the Earth to the Moon and back.

The ISS is the second brightest object in the night sky after the Moon. What makes it so bright is that it reflects sunlight off its solar panels. Knowing where to look for the Space Station, one can see it with the naked eye as a bright light moving at great speed across the night sky until it passes out of sight. The last week of March is a good time to spot the International Space Station over Ottawa when it will be passing by in the early evenings.

The first artificial satellite to be launched into space was Sputnik 1, launched on October 4, 1957 by the USSR. Today, there are over 2,000 functioning satellites launched by different countries, orbiting Earth. These consist of surveillance satellites, weather satellites, remote sensing satellites, communication satellites and navigational satellites.

Artificial satellites in low orbit (300km to 500km) above the Earth, can be seen with the naked eye when they reflect sunlight from their metallic bodies and solar panels. The brightness depends on the size and altitude of the satellite. The ideal time to look for satellites is 1 hour after sunset, especially in the spring and summer when the Earth’s shadow is low in the sky. Dozens of satellites can be seen with the naked eye, on a clear night.

To the naked eye, the artificial satellites look like a white bright star gliding steadily against the background of stars. You will know that you are looking at a satellite and not an airplane because there will be no sound or flashing lights. The satellites travel at a speed of 28,000 km/h crossing the sky in about 2 to 3 minutes and then disappearing out of sight once they enter the Earth’s shadow. Most satellites move in a west to east direction, but others have orbits passing over the polar regions, and can be seen moving from north to south or south to north.

There is a group of satellites known as Iridium communication satellites, which consist of 66 active telecommunication satellites in low Earth orbit. They have a peculiar shape with three shiny door-sized antennas. When one of these antennas is lined up to reflect sunlight towards Earth, the satellite appears as a moving streak of light that gets remarkably bright, producing a bright flash in the sky, fading away after several seconds and disappearing out of sight.

Here is a list of websites to help find exactly when and where the International Space Station and other satellites pass over Ottawa.

<a title="link opens in a new window or tab" href="https://in-the-sky/org/satpasses.phphttps://in-the-sky/org/satpasses.php
Photo Caption: The International Space Station will be passing over Ottawa on seven consecutive evenings from March 24 to 31. Each appearance will last only a few minutes and relies on clear skies and precise timing for best viewing. See page 18 of this issue for a chart of ISS fly overs and other celestial events this month by day and time. Photo courtesy of NASA.

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