This week in What’s Up is not an impressive deep sky object or beautiful planet but something that humanity sent into space – the JWST.

It’s not often that you can see a human-made object in space at the eyepiece. The International Space Station can be seen with the unaided eye as it orbits very close to Earth, about 400 kilometers, and is the size of a football field. Thus, it is one of the brightest objects in the night sky after the Moon. 

It’s even rarer still to be able to see a human-made object beyond low Earth orbit, as spacecraft are usually small and don’t reflect a lot of light. 

The JWST is different, however, as a key part of its design is to reflect a lot of light, and therefore thermal energy, away from the telescope to keep it cool. This makes it very bright and possible to see, even at 1.2 million kilometers from Earth. 

Another exception is rocket stages in low or medium orbit while firing their engines or venting after a mission, as the plumes of gas can be illuminated by the Sun and be seen with the unaided eye.

Since its launch back on Christmas Day 2021, the long-delayed telescope has completed almost all of its critical deployments, including its five-layer sunshield which passively lowers the telescope’s temperature from a blistering 55˚ Celsius to (as of January 13) an incredibly low -200˚ Celcius, just a few dozen degrees above absolute zero, the coldest anything can get. It will need to get a few degrees cooler still before beginning observations. It needs the sunshield to keep its instruments cool without needing a complicated liquid helium cryocooler, though it does have one of those as well. Its mid-infrared instrument needs it to reach -267˚C, just six degrees above absolute zero, to function best.

The sunshield has hundreds of square meters of shiny silver Kapton insulation, and this makes the sun-facing side of the spacecraft quite bright – bright enough that you should be able to see it at the eyepiece of a telescope. According to one source, it will be roughly magnitude +16, which is within the range of small observatories and large amateur telescopes such as a 10-inch or larger Dobsonian.

The JWST is nicely placed in the Northern Hemisphere night sky as it heads out to its ultimate destination at Earth-Sun Lagrange 2, a million and a half kilometers away from Earth. Currently, it is in between the constellations of Orion and Canis Major. It reaches its highest point in the sky around midnight Central time every night between now and the end of January.

To find it, look at the triangle formed by the bright stars Sirius, Betelgeuse, and Alhena. The JWST is between Betelgeuse and Sirius, closer to Betelgeuse. It’s due south of Alhena, just lower than the line between Sirius and Betelgeuse.

Many GoTo telescopes, which use a computer and electric motors to point the telescope at an object automatically, allow the user to input celestial coordinates of right ascension and declination of an object not in its database for the telescope to find. At 05:00 UTC on January 14, the JWST will be at 6 hours 39 minutes 33.5 seconds right ascension and 2 degrees 41 minutes 4.8 seconds declination. We will have an interactive finding chart available in the show notes for this episode so you can determine a more precise area in the sky for your observing location.

Remember, go outside and look up.

More Information

Where is Webb (NASA)

About the Sunshield (NASA)

Will the James Webb Space Telescope be visible from earth? (Stack Exchange)