Astronomy Magazine
Places · Spaceport
Wenchang Space Launch Site
China's coastal pad, close enough to the equator to matter and able to take the wide Long March 5 by sea rather than by rail tunnel.
- Where
- Hainan, China
- Coordinates
- 19.61°N 110.95°E
- Since
- 2016
- On the map
- Show me
- More
- cmse.gov.cn
The sky from here
The sky over this spot is zone 4 — suburban edge, Bortle 4–5, with a naked-eye limit around magnitude 5.7–6.5. The Milky Way is a faint band overhead and gone lower down. The sky is noticeably grey rather than black.
Against that sky 99 of the 110 Messier objects are straightforward in 10×50 binoculars and 100 in a 130mm, with 21 reachable by eye alone. The nearest sky of Bortle 2 or better lies about 52 km south-east of here.
The Sun drops far enough below the horizon here for full astronomical darkness on every night of the year — which is not true of anywhere much further from the equator.
At its highest the galactic centre stands 41° up, which is the difference between a Milky Way with depth in it and a smear along the horizon. Of the 110 Messier objects, none are circumpolar and every one of them rises at some point in the year.
The sky here is kindest to Beehive Cluster, Black Eye Galaxy and Crab Nebula, each of which passes within a few degrees of overhead — an object at the zenith is being seen through the least air it will ever be seen through, and the difference against the same object low in the south is not subtle.
Read at 19.61°N 110.95°E. Darkness is estimated rather than measured; everything else follows from the latitude and holds along the whole parallel. How accurate this is.
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Questions
What part of the sky never rises at Wenchang Space Launch Site?
Everything south of declination −70°. From 19.6°N that is a cap 20° in radius centred on the south celestial pole, which is 2.9% of the whole celestial sphere. It is out of reach permanently rather than seasonally: no time of year and no instrument brings it above the horizon. The matching 2.9% around the north celestial pole is the same geometry inverted, and never sets.
How many hours of true darkness does Wenchang Space Launch Site get?
Between 7 hours 54 minutes on the shortest night of the year, around 21 June, and 10 hours 26 minutes on the longest, around 21 December. That counts only proper astronomical night, with the Sun eighteen degrees down; the merely-dark hours either side of it are longer. The sky here reaches it on every night of the year, which is not true much further from the equator.
What orbits can be reached from Wenchang Space Launch Site?
Anything inclined at 19.6° or more, for free. A rocket launched due east from 19.6°N arrives in an orbit inclined at 19.6° — the shallowest the site can reach without spending propellant to turn the plane — and steeper orbits are simply a matter of launching on a different heading. Steeper targets cost nothing extra: the 51.6° of the Space Station, and the near-polar sun-synchronous orbits the Earth-observation fleet uses, are all reachable directly. Shallower is where it gets expensive. Every one of the 19.6° between here and the 0° of a geostationary belt is paid for in a plane change, which is why equatorial pads are worth building even in inconvenient places.
How far is Wenchang Space Launch Site from the other sites on this map?
FAST — the Five-hundred-metre dish is the nearest thing to it here — 792 km to the north-west. The nearest other spaceport is Xichang Satellite Launch Center, 1,320 km to the north-west. Measured as the great circle between coordinates, which is the shortest path across the surface and rarely the one you could travel.