ISS Pass Time Predictor
Track the International Space Station in real time and find out when it will pass over your location. See live position, current altitude, speed, and distance from you — updated every 3 seconds directly from NASA telemetry.
What Is the International Space Station?
The International Space Station (ISS) is a modular space station in low Earth orbit, a collaborative project between NASA (US), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada). It has been continuously inhabited since November 2, 2000, making it the longest running human presence in space — over 24 years. The station measures approximately 109 meters wide and 73 meters long, roughly the size of a football field, with a mass of 420,000 kg. It serves as a laboratory for scientific research in microgravity, a testbed for space technologies, and a stepping stone for future deep-space missions including the Artemis lunar program. As of 2026, over 270 people from 21 countries have visited the ISS.
How to Spot the ISS From the Ground
The ISS is the brightest man-made object in the night sky and can be seen with the naked eye from any location on Earth between 51.6° north and south latitude — covering nearly all populated areas. It appears as a bright, steady white dot (it does not blink like aircraft navigation lights) moving smoothly across the sky from west to east in about 6 minutes. The best viewing conditions are in the hour after sunset or before sunrise, when the observer is in darkness but the station is still illuminated by sunlight. During these "golden windows," the ISS can reach magnitude -5.9 — brighter than Venus. Use NASA's free Spot the Station website or the ISS Spotter, GoISSWatch, or MyShake apps for precise sighting predictions including elevation angle, direction, and brightness for your exact location.
Understanding the Live ISS Data
This tracker uses the wheretheiss.at API, which receives position data from NASA's Trajectory Operations and Planning Office (TOPO) and updates the ISS ground track in near real-time. The latitude and longitude show the point on Earth's surface directly below the ISS (the sub-satellite point). Altitude is the vertical distance from Earth's surface, which averages around 408 km and fluctuates as the station's orbit naturally decays due to atmospheric drag and is periodically reboosted. Speed is the orbital velocity relative to Earth's surface, approximately 7.66 km/s (27,600 km/h). The distance from your location is the total 3D distance from you to the ISS, combining the horizontal ground distance and the ISS altitude. When the ISS is directly overhead, this equals roughly its altitude; when on the other side of the world, it can exceed 13,000 km.
About the Pass Time Estimation
The pass time estimation in this tool uses a simplified orbital mechanics model based on the ISS's current position, its 92-minute orbital period, and your location's latitude and longitude. The ISS's orbital inclination of 51.6° means it sweeps over a different strip of Earth's surface on each orbit, shifted approximately 2,600 km westward due to Earth's rotation. The tool calculates when the ISS ground track will next come closest to your coordinates, giving a rough estimate of the next overhead pass. Note that this is an approximation — actual visible passes depend on elevation angle (must be above 10° for a good sighting), cloud cover, and local horizon obstructions. For precise pass predictions with times and viewing directions, always verify with NASA's official Spot the Station resource at spotthestation.nasa.gov.
Frequently Asked Questions
How often does the ISS pass over any given location?
The ISS orbits Earth approximately every 92 minutes, completing about 15.5 orbits per day. However, it only passes directly overhead for any specific location roughly 2-5 times per week due to Earth's rotation shifting each orbit's ground track by about 2,600 km westward. During certain weeks the ISS may not be visible at all from your location if orbits are not aligned.
How fast does the ISS travel?
The ISS travels at approximately 7.66 km/s (27,600 km/h or 17,150 mph) relative to Earth's surface. This is about 22 times faster than a rifle bullet. At this speed it traverses the entire width of the United States in about 10 minutes. Each time it passes overhead, it moves from horizon to horizon in approximately 6 minutes.
What altitude does the ISS orbit at?
The ISS maintains an orbital altitude of approximately 400-420 km (250-260 miles) above Earth's surface. This varies slightly due to atmospheric drag. NASA periodically boosts the orbit using thrusters. The height is a balance between avoiding rapid drag and staying close enough for efficient cargo and crew missions.
Can I really see the ISS with the naked eye?
Yes, the ISS is the third brightest object in the night sky after the Moon and Venus. It appears as a bright, steady (non-blinking) white dot moving smoothly across the sky, reaching magnitude -5.9 under ideal conditions. The best viewing windows are in the hour after sunset or before sunrise, when you are in darkness but the station is still in sunlight.
How does the pass time estimation work?
This tool fetches the current ISS position from the wheretheiss.at API, updated every 3 seconds. To estimate the next closest approach to your location, it calculates the great-circle distance between your coordinates and the ISS, then uses the 92-minute orbital period to project when the ground track will next sweep closest to your location. For precise sighting windows with elevation angles, use NASA's Spot the Station service.
Why is the ISS distance so large?
The distance shown is the 3D distance from your surface location to the ISS, including its altitude of ~408 km plus the horizontal distance across Earth's surface. When the ISS is directly overhead the distance equals ~408 km. When on the opposite side of Earth it can exceed 10,000 km. The distance updates every 3 seconds as the ISS moves.
How many people are on the ISS right now?
The ISS typically houses 7 crew members at full capacity. During crew transitions this can temporarily be fewer. The station has been continuously inhabited since November 2, 2000, making it humanity's longest ongoing human spaceflight mission. Crew members typically spend 6 months on board before returning to Earth.