With Elon Musks SpaceX launching its Starlink satellites at a rapid pace, the chances of seeing chains of the objects whizzing across the night sky are becoming better over time.
For those of us without a high level of technological literacy, a range of websites have been set up showing when a Starlink chain, or any other bright object put into orbit, will be passing in the skies overhead.
One that Nelson-based rocket scientist Dr Duncan Steel particularly likes is Heavens Above. At no cost, users can put their location into the site, which provides a daily list of all bright satellites that will be in the sky and potentially visible from that point, how bright they will be, the direction to look, and how high they will get in the sky.
Theres also a page showing the changing positions of all the Starlink satellites in orbit, while the International Space Station (ISS) also gets special attention.
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Objects in orbit are normally only visible for a few hours after sunset, and a few hours before sunrise. Thats when the object in space is in sunlight but the observer on the ground is in darkness.
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A SpaceX Falcon 9 rocket lifts off from Kennedy Space Centre on March 4, carrying 60 Starlink satellites.
With three launches of about 60 satellites each mission so far in March, SpaceX has taken the number of Starlink satellites in orbit to 1300. For some weeks after being launched each group of satellites travels in a gradually lengthening line, providing the startling site of a chain of lights racing across the night sky.
The Heavens Above page just for Starlink satellites shows the position of each one at any moment. Most are in a moving grid arrangement, but the satellites from recent launches appear as long straight lines circling the globe, and frequently crossing New Zealand.
Its very easy to use, once you get the hang of it, Steel said.
The Starlink satellites became visible from Earth as a line about a week after being launched, and stays in that formation with increasingly big gaps between each satellite for about a month, he said.
These things are whizzing by all the time.
A train of SpaceX Starlink satellites pass overhead.
Starlink satellites were a good size about the size of a big kitchen table, but nowhere near the size of the ISS. Its the size of a rugby field, Steel said.
Its a huge thing. The space station is the third brightest thing you are going to see in the sky behind the Sun and the Moon. In the right conditions, its brighter than the planet Venus.
Brightness and the highest point a satellite would reach in the sky both of which are available on Heavens Above were key things to check to know how easy objects in orbit would be to see from the ground.
With the brightness magnitude number the smaller the number the brighter it is, Steel said.
Someone with good eyesight might be able to see something as high as about 6.5 on a very dark night. But what you really want is about magnitude 3.
Brightness was measured on a logarithmic scale, so something with a brightness of 3 was about 10x brighter than something with a brightness of 5.8.
When it came to the highest point of an object, it is good to look for something that was 40-60 degrees above the horizon with 90 degrees being directly overhead, Steel said.
Brightness and height goes hand-in-hand. Brightness will be better if it goes higher.
The International Space Station seen from a Soyuz spacecraft.
For example, Heavens Above shows 60 satellites from the Starlink L20 launch on March 11 being visible from Porirua on Thursday evening between about 8.58pm and 9.03pm. Brightness will range from 2.2 to 2.4, and the highest point from 69 degrees to 78 degrees.
The weather forecast for Porirua is promising, so if the sky is largely cloudless at that time, residents of the area looking at the sky roughly to the south could see quite a show.
As for the ISS, again as an example, it will be visible from Porirua weather permitting for a few minutes each morning from March 23 to 25.
The best show at that time will be on the last of those days, when the station will have a brightness of 3.7, and get to a height of 87 degrees, just seconds before 6.44am. Look roughly north for that.
The ISS can be seen even from the middle of a city, Steel said. It appears to move at much the same rate as a high flying aircraft, and takes typically five minutes to go from horizon to horizon.
Nasa also had a webpage showing when the ISS would be visible from Earth.