by If the weather is clear this evening, we invite you to go outside and stare up any time from one to two hours after sunset.
If you’re lucky enough to be located far away from any bright lights, break out a long lounge or deck chair and get comfortable. When your eyes are fully adapted to the dark, you may be able to count hundreds of stars of varying brightness.
But you might also see some other interesting sights, including the largest and brightest object currently in Earth’s orbit: the International Space Station.
Related: Track the ISS: How and where to see it
You may catch a glimpse of an extraterrestrial invader; a sudden flash of light, lasting no more than a second or two at most and perhaps leaving a short incandescent trail behind.
Ancient stargazers believed that such a sight was a star falling from its fixed position in the sky. We call these meteors today, although the term “shooting star” and “shooting star” are still widely used. Such objects are usually particles no larger than a pebble or grain of sand, which crash into our upper atmosphere at high speeds of up to 45 miles (72 km) per second; their kinetic energy is almost instantly converted to light creating a shooting star effect. Most meteors first appear at an altitude of 80 miles (130 km) and disappear about a second later at perhaps 40 miles (65 km).
Then there is another group of invaders that have been with us since the beginning of the space age, some 67 years ago: Artificial satellites.
Unlike meteors, they are much larger: In fact, man-made structures that circle our Earth and cruise in orbit around our home planet at average speeds of “only” 5 miles (8 km) per second.
Perhaps the best visual description of a satellite was the late English satellite observer Desmond King-Hele (1927-2019). In his excellent book, “Watching the Earth’s Satellites” (Van Nostrand Reinhold Company, 1983), he wrote: “A satellite looks like a star that has lost its senses and decided to move to another part of the sky.”
Satellites are visible at night because their metallic skins are illuminated by the sun. A satellite entering the Earth’s shadow immediately disappears from view and follows an unprecedented path until it reemerges in sunlight.
How many?
Currently, if you go outside and carefully study the sky between 30 minutes and two hours after sunset, or from two hours to 30 minutes before sunrise, there is a good chance that you will see as many as 15 to 30 satellites, at a range of brightness. from as bright as the brightest stars (zero or first magnitude) down to relatively faint objects around fourth magnitude. This shouldn’t surprise you too much when you consider just how many objects are orbiting the Earth now.
The first satellite was Sputnik 1, launched in October 1957. Since then, approximately 9,500 satellites have now orbited the Earth. Most of these are active payloads, but there are also 100 million pieces of “space junk” ranging in size from as large as 30 feet, down to about the size of a softball, and literally millions of smaller pieces that could be disastrous nonetheless. They hit another orbiting object. The US Space Command in Colorado Springs, Colorado maintains a constant watch for all orbital debris.
Most satellites are too faint to be seen with the unaided eye. But depending on his count, hundreds or more can be seen with the unaided eye. These are the satellites that are large enough (over 20 feet or 6 meters long) and low enough (100 to 400 miles or 160 to 640 km above Earth) that they are easiest to see.
The biggest!
TOP TOP PICK:
Looking for a telescope to see the ISS in the night sky? We recommend the Celestron Astro Fi 102 as the top choice in our best beginners telescope guide.
The International Space Station (ISS), built and currently maintained by the United States, Russia, the European Space Agency, Japan and Canada, is the largest and brightest of all man-made objects. in Earth’s orbit. The station’s solar arrays are 240 feet (73 meters) wide, which exceeds the wingspan of a Boeing 777. The station itself is 357.5 feet (108 meters) long, or just shy of the length of a football field, with its including the final zones. It weighs 925,335 pounds (462.7 tons).
Orbiting the Earth at an average altitude of 260 miles (420 km) and at a speed of 17,500 miles (28,200 km) per hour, it can appear to move as fast as a high-flying jet airliner, sometimes taking as many as six or seven minutes to cross the sky. It can easily be mixed with aircraft lights.
Nominally, it appears white with a slight yellow tinge and nominally its visual magnitude can reach an amazing -1.8 (equal to Sirius, the brightest star in the night sky) although it can sometimes be seen to shine as bright with a magnitude of -5.6 at its brightness. , which is twice as bright as the planet Venus!
Although the ISS appears as a very bright moving star to the unaided eye, those who have been able to train a telescope on it have been able to detect its T-shape as it crosses their field of view. Some were able to track the ISS with its scope by moving it along the projected path. Those who have obtained a good view describe the body of the space station as brilliant white, with the solar panels appearing red in color.
Simply put: If the ISS is moving across your horizon, you can’t miss it!
Many windows of viewing opportunity
From now until the end of May, North Americans will get many opportunities to see the ISS fly past their homes, mainly due to seasonal circumstances. As we approach the summer solstice on June 20, nighttime hours are getting shorter and the time that a satellite in low-Earth orbit (like the ISS) can remain illuminated by the sun can be extended into the night, which could be. never achieved during other times of the year.
As the ISS orbits the Earth approximately every 90 minutes on average, this means that it can be seen not just on a single pass, but on several successive passes.
In most places there are two types of passes. In one case, the ISS first appears toward the southwest part of the sky and then sweeps over toward the northeast. But other times a second type of pass can be seen, with the ISS appearing first towards the north-west of the sky and sweeping over towards the south-east.
In the most extreme cases, you might be able to catch the ISS up to four or more times in one day!
Case in point: From New York City on Friday, May 10, the ISS will take about 3.5 minutes to skim low over the north-northern horizon from west-northwest to northeast beginning at 2:08 a.m. EDT. A slightly higher pass, taking a northwest to east-southeast path and lasting nearly 5 minutes will begin at 3:44 a.m. Later that evening, at 10:01 p.m., a significantly higher pass will begin, more brighter and longer in the west-southwest and will finish almost 7 minutes later in the northeast. Along the way, the ISS will climb two-thirds of the way up from the north-northwest horizon to the point just above it.
Later that evening, the ISS will make a much lower pass, taking 2 minutes to track from northwest to northwest-northwest starting at 11:39 pm.
Where and when should you look?
So what is the viewing schedule for your particular hometown? You can easily find out by visiting one of three popular websites:
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Spot the Station – This site will tell you when and where to see the ISS. All you have to do is type in your city or town, then click on the map pin to get all the details. You can even sign up to receive email or text alerts when the space station is in flight.
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The Skies by Chris Peat above – This site will not only provide you with sighting information for the ISS, but also for Tianhe-1. You need to register first and then you can input your location to create a viewing schedule.
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Live Real Time Satellite Tracking – Like the Skies Above, you can get visual information for both the ISS and Tianhe-1. When you are logged in this site will automatically provide data based on your IP address, or you can set a “custom” site.
Predictions calculated a few days ahead of time are usually accurate within a few minutes. However, they can change due to the slow decay of the space station’s orbit and periodic re-boosts to higher altitudes. Check often for updates.
Clear skies and happy hunting!
Joe Rao serves as an instructor and guest lecturer at New York’s Hayden Planetarium. He writes about astronomy for Free natural history magazine,the The Farmers’ Almanac and other publications.
