A unique celestial event is about to unfold for skywatchers across most of the U.S. and southern Canada. The International Space Station (ISS) and China’s space station, Tiangong, will be visible in the sky within a half hour of each other on several occasions from now through July 8.
The ISS, operated by NASA, is one of the largest human-made objects in space, with a total mass of approximately 450,000 kilograms. It orbits Earth at an average altitude of 400 kilometers and appears as bright as Jupiter when viewed from a distance. The ISS will be visible in the sky from late evening to early morning hours.
Tiangong, operated by China’s Manned Space Agency, is smaller than the ISS but still a prominent object when moving across the nighttime sky. It orbits Earth at an average altitude of 400 kilometers and appears as bright as Venus when viewed from a distance. Tiangong will be visible in the sky from late evening to early morning hours.
Both space stations are visible because they circle the Earth every 90 minutes on average, with their orbital altitudes differing slightly due to different inclinations. This alignment creates viewing windows of opportunity for observers in North America and Europe.
To witness this event, you can use online resources such as Chris Peat’s Heavens Above or NASA’s Spot the Station app. Simply input your location based on latitude and longitude to get accurate sighting data for both space stations. The apps will provide information on the time of each flyover, visibility duration, maximum height reached in the sky, and direction it appears and disappears from your field of view.
Astronomer Joe Rao serves as an instructor and guest lecturer at New York’s Hayden Planetarium and writes about astronomy for various publications. He is a veteran meteorologist and eclipse chaser who also tracks lunar and solar eclipses, meteor showers, and more on Twitter and YouTube.
Source: https://www.space.com/stargazing/how-to-see-chinas-tiangong-space-station-and-the-iss-in-the-predawn-sky-this-week