I see this bright star-like thing in the Western sky over the Pacific every night. (I’m not crazy, other people see it too) It’s maybe as bright as Venus, but stays up way later than I’d expect Venus to - it’s still there at 10pm. It moves too slowly for a plane, but seems to move too quickly for a planet. It doesn’t move visibly, but if you watch it for, say, half an hour, it will have moved a little.
One of my more astronomically enabled neighbors concluded that it doesn’t follow the Ecliptic, meaning it’s probably not a planet (right?)
I’ve searched all the amateur astronomy web sites I could find - you’d think they’d be all over something as obvious as this, but no dice. Perhaps in such circles it’s considered lacking in class to enquire about such obvious objects?
I also checked out the various sites that allow you to find the current position of the ISS. They agreed with where I saw it - over the Pacific - but that still allows quite a big margin of error.
So, is it or isn’t it? Am I being confused by Venus staying up an especially long time? Or is it really the ISS?
Side note - whatever happened to the effort to find a catchier name than “International Space Station”? Is that now to be the official designation?
The space station moves pretty fast and would only be visible for a matter of minutes and nevr in the same place day after day. What you are seeing is probably Venus.
The site posted by DarrenS states I’ll be able to see the ISS around 9:50 tonight. It then goes on to say the “Approach (Deg-Dir)” will be 29 above NNE, and the “Departure (Deg-Dir)” will be 12 above ENE.
That means that the ISS will first be visible 29 degrees above the horizon in the north north east (ie 22.5 degrees to the east of north). It will travel across and then cease to be visible 12 degrees above the horizon in the east north east (ie about 67.5 degrees east of north.
You are best off looking for a time and date when it rises at one point, crosses high across the sky and sets at another point. It usually takes a good few seconds to pick it up with your eye, and if it’s just a short pass low on the horizon, you may well miss it altogether.
In my opinion, heavens-above (the site mentioned by the bad astronomer above) gives better descriptions but it is a little more involved to use.
OK, so what is that I see (for me it’s on the W, about 20° above the horizon. I had been assured that this was the ISS, and having no reason not to, believed it.
If you are seeing something that does not move quite rapidly across the sky, then it is not the ISS. The ISS is not just hangin’ about. That sucker moves.
The couple of times I have seen it do a high pass overhead, it goes from one horizon to the other in maybe a couple of minutes.
If it stays in the sky for several hours, but moves relative to the stars night to night, it is what they call in Greek, a wanderer, a planet. Your candidates are: Mercury, Venus, Mars, Jupiter, Saturn and very rarely, Uranus, which are the visible planets. (But you will never likely see Uranus with the naked eye. You must have excellent conditions and good eyes.) You also state that it is not Venus, and is visible for several hours, which also rules out Mercury, which has less visibility time than Venus. Therefore, you are seeing Mercury, Jupiter or Saturn. Time to get a powerful pair of binoculars and a tripod to hold them steady.
No visible moons or visible rings, Mars.
Visible rings, Saturn.
Four visible moons, no visible rings, Jupiter.
Venus has a maximum elongation of about 45 degrees, which means it can stay up for up to about three hours after sunset. We’re not yet to the equinox, which means that the sun is still setting later than 6:00 PM in the Northern Hemisphere. Add in Daylight Savings Time, and sunset is after 7:00, so it’s perfectly reasonable to see Venus at 10:00 PM. And currently, in Montana, Venus is in fact setting at just after ten.
Jupiter, Saturn, and Mars are not currently visible in the evening sky. And the rings and moons are not visible to the naked eye, so you can’t tell them apart that way.
And it can be very difficult to judge the position of the ecliptic, without reference to the constellations, because it’ll be at a different height in the sky during day and night. In the summer, when the ecliptic is high in the sky during daytime, it’ll be low in the sky at night.
Thanks Chronos - that nails it I think. I’ve been misled into thinking of Venus as “The Morning/Evening Star” and that it must follow the Sun, setting shortly after it.
Note: with an orbital period of 90 minutes, if the ISS passes directly overhead it should be in the sky for 45 minutes (from horizon to horizon, assuming a flat horizon for a full view of the sky). It may have appeared much faster as it actually speeds up as it gets higher in the sky and moves much more slowly near the horizons. My guess is you either (1) saw it disappear into the Earth’s shadow or (2) you just assumed it had gone below the horizon when it hadn’t or (3) it didn’t pass directly overhead.
Sucker still moves very fast across the sky compared to any object a lunar distance or farther.
No I think JSPrinceton, you need to think harder about the geometry involved. Your assumption that an orbiting object will be visible for half its orbital period would be true if one were standing on one or other side of a planet shaped like a piece of paper.
But actually, we are standing on a globe over 12000km in diameter, looking at an object only 400 km up. To bring that down to imaginable proportions, think about a circle 12 cm across drawn on a piece of . The ISS is a dot 4mm away from the outside of the circle. You are an ant on the circle just under the dot. Now draw a line that is tangential to you, just kissing the circle, representing your horizon. How much of the total orbit of the dot are you going to be able to see?
If you don’t believe me, check this site, which while not exactly on point, has some diagrams that illustrate.
No I think JSPrinceton, you need to think harder about the geometry involved. Your assumption that an orbiting object will be visible for half its orbital period would be true if one were standing on one or other side of a planet shaped like a piece of paper.
But actually, we are standing on a globe over 12000km in diameter, looking at an object only 400 km up. To bring that down to imaginable proportions, think about a circle 12 cm across drawn on a piece of paper. The ISS is a dot 4mm away from the outside of the circle. You are an ant on the circle just under the dot. Now draw a line that is tangential to you, just kissing the circle, representing your horizon. How much of the total orbit of the dot are you going to be able to see?
If you don’t believe me, check this site, which while not exactly on point, has some diagrams that illustrate.
No I think JSPrinceton, you need to think harder about the geometry involved. Your assumption that an orbiting object will be visible for half its orbital period would be true if one were standing on one or other side of a planet shaped like a piece of paper.
But actually, we are standing on a globe over 12000km in diameter, looking at an object only 400 km up. To bring that down to imaginable proportions, think about a circle 12 cm across drawn on a piece of paper. The ISS is a dot 4mm away from the outside of the circle. You are an ant on the circle just under the dot. Now draw a line that is tangential to you, just kissing the circle, representing your horizon. How much of the total orbit of the dot are you going to be able to see?
If you don’t believe me, check this site, which while not exactly on point, has some diagrams that illustrate.
I’m not sure what I was thinking of but it was a lot more complicated in my mind than that…