What Is Tiangong?
Tiangong (meaning "Heavenly Palace" in Mandarin) is China's permanently crewed space station and the second fully operational orbital outpost in the world today. After years of development and a series of prototype stations (Tiangong-1 and Tiangong-2), China completed the current T-shaped station in late 2022 and has kept it continuously occupied ever since.
The station orbits Earth at an altitude of roughly 390 km, circling the planet every 91 minutes at an inclination of 42.0 degrees. That orbital tilt means Tiangong passes over a slightly narrower band of latitudes than the ISS, generally staying between 42 degrees north and 42 degrees south. If you live in that range, you can see it cross your sky on a regular basis.
Tiangong is smaller than the International Space Station, but it is a fully self-contained laboratory and living space. Three crew members typically live aboard at any given time, conducting science experiments, maintaining the station, and performing spacewalks. For China, Tiangong represents a major milestone: an independent, long-term human presence in low Earth orbit.
The Three Modules
Tiangong is made up of three pressurized modules, each launched separately and assembled in orbit over about 18 months.
Tianhe (Core Module)
Tianhe, which translates to "Harmony of the Heavens," was the first piece to reach orbit in April 2021. This is the control center and primary living area for the crew. It contains sleeping quarters for three, a small galley, exercise equipment, and the main guidance, navigation, and communication systems. Tianhe also serves as the docking hub, with ports for visiting Shenzhou crew vehicles and Tianzhou cargo ships.
Wentian (Laboratory Module I)
Launched in July 2022, Wentian ("Quest for the Heavens") is the first of two science modules. It houses experiment racks for life sciences and biotechnology research, along with a backup control center and an additional airlock for spacewalks. Wentian also has a small robotic arm that works in coordination with a larger arm on the Tianhe module.
Mengtian (Laboratory Module II)
Mengtian ("Dreaming of the Heavens") arrived in October 2022, completing the station's T-shaped configuration. This module focuses on microgravity physics, fluid science, and materials research. It features a cargo airlock that can move experiments and equipment between the pressurized interior and the vacuum of space, making it possible to expose samples to the space environment without requiring a crew member to go outside.
Together, the three modules give Tiangong a total mass of approximately 66 tonnes and about 110 cubic meters of pressurized volume. That is compact compared to the ISS, but more than enough for a crew of three to live and work comfortably for months at a time.
Who Lives on Tiangong?
Tiangong is crewed by taikonauts selected and trained by the China Manned Space Agency (CMSA). Each crew typically consists of three people who arrive aboard a Shenzhou spacecraft and stay for approximately six months before handing over to the next rotation.
As of early 2026, the Shenzhou-19 crew is aboard the station. The three-person team launched in late October 2025 and is expected to remain until spring 2026, when the Shenzhou-20 crew will arrive. During handover periods, both crews overlap for about a week, briefly bringing the station population to six. These handovers allow the outgoing crew to walk the newcomers through ongoing experiments and station operations before departing.
China's taikonaut corps has grown steadily over the past several years. Early Shenzhou missions carried mostly military test pilots, but recent crews have included flight engineers and payload specialists with backgrounds in aerospace engineering and scientific research. CMSA has also begun selecting crew members from civilian universities, a sign that the program is broadening its reach.
If you want to check how many people are in space right now, Tiangong's crew makes up a significant share of the total. On most days in 2025 and 2026, the combined count across the ISS and Tiangong sits somewhere around 9 to 10 people.
Science Aboard Tiangong
Microgravity research is the primary reason Tiangong exists. The Wentian and Mengtian modules together house dozens of experiment racks spanning multiple scientific disciplines.
- Materials science: Experiments on crystal growth, metal alloys, and semiconductor production in microgravity, where the absence of convection allows for purer samples than anything possible on the ground.
- Life sciences: Studies on how cells, plants, and small organisms respond to spaceflight. These experiments feed into long-term planning for human missions beyond low Earth orbit.
- Fluid physics: Research on how liquids behave without gravity, relevant to everything from fuel management in spacecraft to industrial processes on Earth.
- Fundamental physics: Mengtian carries an ultracold atomic physics rack that can cool atoms to near absolute zero, enabling precision measurements of physical constants.
Beyond the internal labs, Tiangong's external experiment platforms allow payloads to be exposed directly to the space environment. Mengtian's cargo airlock makes it straightforward to cycle experiments in and out without a spacewalk.
One of the most anticipated additions to the program is the Xuntian Space Telescope (also called the Chinese Survey Space Telescope, or CSST). Xuntian is designed to fly in a co-orbital path near Tiangong, so it can periodically dock with the station for servicing, repairs, and instrument upgrades. With a 2-meter primary mirror and a field of view roughly 300 times larger than the Hubble Space Telescope, Xuntian is expected to conduct wide-field surveys of galaxies, dark matter, and dark energy over its planned 10-year mission.
Tiangong vs. the ISS
People often compare Tiangong and the ISS. They serve similar purposes, but the two stations differ significantly in scale, partnership structure, and orbital parameters. Here is how they stack up side by side.
| ISS | Tiangong | |
|---|---|---|
| Mass | ~420,000 kg | ~66,000 kg |
| Pressurized volume | ~916 m³ | ~110 m³ |
| Crew size | Typically 7 | Typically 3 |
| Orbital altitude | ~420 km | ~390 km |
| Inclination | 51.6° | 42.0° |
| Partner nations | 15+ (NASA, ESA, JAXA, CSA, Roscosmos) | China-led (CMSA) |
| First module launched | 1998 (Zarya) | 2021 (Tianhe) |
| NORAD ID | 25544 | 48274 |
The ISS is about six times heavier and has roughly eight times the pressurized volume. That difference reflects its role as a multinational laboratory shared by more than a dozen countries. Tiangong, by contrast, was designed from the start as a more compact, single-nation station. It is easier to maintain and far less expensive to operate, and China has full control over its schedule, experiments, and crew selection.
Both stations orbit at similar altitudes and are visible from the ground under the right conditions. The ISS is considerably brighter (around magnitude -4 to -3, rivaling Venus), while Tiangong is dimmer but still easy to spot at roughly magnitude +1 to +2. Their different inclinations mean the ISS is visible from slightly higher latitudes, while Tiangong favors observers closer to the tropics and mid-latitudes.
For more on every station currently overhead, see our guide to every space station currently in orbit.
How to Spot Tiangong
Tiangong is tracked by NORAD under catalog ID 48274. Like the ISS, it is visible to the naked eye, appearing as a bright, steady point of light moving smoothly across the sky. It does not blink or flash like an airplane. A good pass lasts two to five minutes from horizon to horizon.
The best times to see Tiangong are during the hour or so after sunset and the hour or so before sunrise. During these windows, you are standing in darkness while the station, 390 km overhead, is still in direct sunlight. That sunlight reflecting off the station's solar panels and white hull is what makes it visible.
To find out exactly when Tiangong will pass over your location, you need a satellite tracking app. I track Tiangong passes with Skytrail, which gives me accurate pass predictions, brightness estimates, and even shows which taikonauts are aboard. It covers both Tiangong and the ISS, so I never miss a visible pass of either station.
A few tips for your first sighting:
- Check the magnitude: Passes brighter than magnitude +2 are easiest to spot. On a clear night away from heavy light pollution, even magnitude +3 passes are doable.
- Face the right direction: Your tracking app will tell you which compass bearing to look at and how high above the horizon the station will appear. Overhead passes are the brightest and longest.
- Give your eyes a minute: Step outside a few minutes early and let your eyes adjust. You do not need a telescope, just clear skies and the right timing.
- Watch for shadow entry: On evening passes, you may see Tiangong suddenly fade and disappear mid-arc as it moves into Earth's shadow. This is normal and actually pretty interesting to witness.
Tracking tip: Tiangong can be tricky to spot since it is dimmer than the ISS. Skytrail gives you precise pass times, sky trajectories, and brightness predictions for Tiangong specifically. I have caught dozens of Tiangong passes this way that I would have otherwise missed.
For a more detailed walkthrough on spotting orbital stations, see our tutorial on how to see the space station from your backyard.