ISS, Tiangong, Satellites Over Puna

[TomK]

That was a really nice pass! Clear but bright skies, but still visible far into the NE. For those who saw it but don't know the night sky so well, the bright star it passed close to is Sirius.

[PaulW]

Got it! Thanks for the "heads up".

[HereOnThePrimalEdge]

Yes! Best view we've had in a long time. I noticed Orion kept a close watch on the ISS as it zipped past Sirius and headed northeast.

You could never convince a monkey to give you a banana by promising him limitless bananas after death in monkey heaven.

[TomK]

While we watched it, I was trying to explain to my neighbor about the ISS orbit and why Friday night it was in a completely different place. I also tried to explain how fast this thing moves.

Imagine, just 15 minutes after it appeared close to Sirius (about the closest approach to Puna tonight), 15 minutes later if was just south of the Great Lakes area on the mainland. That's fast!

[TomK]

Just to give some perspective, though, although the ISS moves quickly, at that speed it would still take about 160,000 years to reach the nearest star...

[PaulW]

I was wondering about the altitude. Turns out it's about 250 miles high - slightly more than the distance to Honolulu.
But a lot closer than anything else in the sky.

[TomK]

Paul - for your info, the 250-mile altitude is an average. Because the ISS is in low earth orbit (LEO) it interacts with an extremely rarified atmosphere, i.e., there are still molecules from the Earth's atmosphere with which it interacts - and that can change daily depending on solar activity. The effect is minute but over time adds up. The orbit is also affected simply by passing over more dense parts of the Earth's crust and the orbit of the Moon. It's a very complicated interaction that is almost impossible to model, but things are improving as we learn more. It also shifts orbit slightly whenever there is a threat of a collision with orbital debris. Even magma shifts below Kilauea affect orbits of LEO satellites.

This is why it's not a good idea to predict sightings for the ISS, Iridium flares or other LEO satellites too far in advance as the orbits are likely to change. The adjustments tend to be very small but over a few days make a big change to predictions.

[lisa]

That was amazing to watch. Great view Kapoho!

[islandlvng]

Last night around 7-730, very bright light passed over hpp coming from Kilauea area. Went out over ocean above kaloli and kept going. Solid light coming, overhead and going. It never changed color, intensity or had any flashing lights. Zero noise.

Was that it? If so very cool to see! Looked unusually low compared to other moving objects we see up there.

[TomK]

Yes, your description suggests you saw it!