BTW I said bottom was apogee. this is incorrect. Should say perigee. (I get peaches and pears mixed up too)
I wonder if the temperature of the craft in the earth’s shadow might give a useful clue? Bob Wilson
The question makes sense but how would you measure it? Would want to look at far-IR and atmosphere is quite opaque.
I mix up ex-pats and teachers-abroad. And others too. Derived from Heavens-above orbital elements, it is down another 0.195 km in 5.63 hours since my previous post, to 12 March 2018 16:09:09 UTC. That is a rate of 0.83 km/day. I'll have to average over some longer periods. The drop rate over random time intervals will be uneven. Full integer number of orbits would be better than fractional orbits, because most of the drag happens during perigee, much less during apogee. Day/night might make a difference too, due to diurnal warming and expansion of the atmosphere below.
Ooooh, day/night sounds good. Also atmosphere is taller near the equator so more deceleration should happen there. Survival below 250 km is always very short so TG1 is by far the largest low thing. Fifteen cubic meters of "glad I'm not there".
Maybe a little word association might help? The Japanese word for pear is nashi, which sounds like the word for nothing. When you've got nothing, you've hit bottom, or "pearigee". It's a stretch, but it might help. At least it might make you laugh. Posted via the PriusChat mobile app.
Not sure that I'd heard that one before, but it certainly makes sense. The planet's rotation gives an equatorial bulge, higher radius there. That produces a slightly lower surface g force, so the atmosphere would also thin a bit slower with elevation. I.e. taller. It will be fun to watch the daily drop rate of an actual satellite, and how quickly it increases, in sort of real time. I've never done this before.
Atmosphere has an equatorial spinny bulge but I understand that surface heating plays a larger role. When Sun is with many spots, it 'heats' upper atmos, and this may favor low latitudes (for ultraviolet) or high latitudes (where charged particles leak in better). All that is delicious science and can be appreciated without 'equations' with funny symbols that folks at large devalue. I think it's because y'all were taught by subliterate teachers, but that's a rant. More or less. TG1 is a glorified beer can that won't hit anybody. But it might lead to fuller appreciation of some aspects of science. When any such things happen, people (who simply want you to know more stuff) ought to think about salesmanship.
If still not known here, if you want to see orbiting objects, eye the sky for one hour before dawn or for one hour after dusk. This will not reward if you have clouds or if your place is too bright from surface-light spray. During such times you can see a small fraction of Earth's orbitalia, but only those reflecting sunlight towards you. If your sky is otherwise dark and open, you will see many small lights crossing your sky for a minute or two. They can be 'known' from Heavens-above. But I'd be satisfied if viewers realize that things now in sky include new things, Bright stars and planets in sky are of a much more durable class.
I believe Sirius is currently due south several hours earlier in the evening. Then some hours after midnight, Jupiter is due south and even brighter than Sirius. I would not normally be up at such times, but this past week have been out in the fields scanning for new calves that might be in distress. And finding gorgeous bright skies the past several nights, with Jupiter being quite prominent. Saturn should appear later, but by then I'm napping until daylight for the next herd welfare check. But no sky watching tonight, the clouds have already arrived, to bring rain then more snow. ========= P.S. The 'South' direction is from my northern-hemispheric-centric viewpoint. Viewers well down in the other hemisphere should look north. And equatorial band viewers should simply look up.
It wasn't optimum viewing as I was in the middle of town, Huntsville AL. Just the brightness suggested a star or planet but the elevation was lower than I've associated with Jupiter. I should have looked for scintillation so I can't rule out a planet. I'll try again tonight from a darker area outside of town with my spotter scope. Bob Wilson
My sympathies. That is probably similar to my adult home in the severely light polluted Seattle-Everett-Tacoma metropolis. But my past ten days have been at the childhood home-farm-ranch, a bit polluted on one side but with a solid national forest and wilderness connection to the Dark Sky Reserve referenced in tochatihu's post: Environmental News | Page 13 | PriusChat Jupiter is now down at a similar low declination as Sirius: -16deg 43min for Sirius, -17deg 20min for Jupiter.
I couldn't find my spotter scope but I did observe it again last night. It is bright enough to be an aircraft landing light but no apparent motion. I could not see a star field behind it. No twinkle so very likely a planet. Bob Wilson
That sounds right. I should have mentioned that Sirius, early evening, currently trails the Sun by 7 hours 10 minutes. It is an now early evening item. Jupiter is an additional 8 hours 38 minutes behind Sirius, or close to 16 hours behind the Sun. So it is now an after-midnight item.
Heavens@17 was an excellent suggestion by fuzzy1. Have been collecting those data since. Rev/day showed a constant increase for 3.3 days, then still constant but with greater slope for 2.4 days. About 50% increase in slope. This inexpert analysis is supported by satflare's re-entry predictions getting earlier. Those now center on April 2.
