From time to time just after dusk looking due west I have observed objects travelling due north with no contrail. They only appear 12 O'clock high for a short, flat arc of about 20 to 30 degrees and lasts for about 5 to 15 seconds depending on the event. No flashing lights of any color are discernable. I can not tell if it is an airliner fairly close but at 30k feet or a polar orbiting satellite reflecting sunlight while I'm in dusk. I've seen the ISS many times and the brightness seems similar. Also, I live in a rural area.

So, what is the best clue to differentiate between the two?

Try going to Heavens-Above and see if they have satelites listed for your area. Otherwise a good pair of binoculars might work.

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Could it be a plane up high enough to still reflect the sun from below the horizon as you see it?

You might also try to time it in degrees per second to see if that rules out anything. 2 degrees per second for a plane at 30K feet would be a speed of about 714 mph. Higher means faster. At 250 miles up, 2 degrees per second comes out to about 31,000 mph, unless I really messed up the math.

At 1.5 degrees per second, it brings the plane down to about 530 mph, but the satellite is still up around 23,000; far too fast to be in LEO.

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A Geek will think he can use that to pick up a girl in a bar.
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Be careful with this. If you are seeing sunlight reflections your binoculars can be a risk to your good eye sight. I would not want you to be pointing any were near the sun. Wait until the sun has set before you go looking in that direction. The heavens above site will help but does not cover all the space junk that could reflect that light you are seeing. I would think you are watching high altitude aircraft transiting your area.

PhantomWolf has the best suggestion (IMO). But, my general rule of thumb is that if it looks like a star or planet, it's most likely a satellite.
A plane catching the setting sun will normally seem a little brighter or sharper and usually be more of a golden color.

Pull out a schedule from heavens-above and do some viewings for a few nights, and you'll get a feel for what they look like.

Thanks everyone for the responses.

I generally observe these events when going to or from the barn bedding down the animals for the night. So, carrying observing equip is not practicable. However, if I carried a stick(ruler) that I could hold up at arms length and do the best I could counting seconds, how should I space the marks to roughly count off degrees.

Also, I am familiar with the flight paths around my property and have only seen private low flying planes travelling due north. If any pilots could clue me in the farm is 40 miles east of Cleveland on Lake Erie.

Your fist held at arm's length is about 10 degrees. Your pinky is about 1 degree, and your thumb is about 1.5-2.

Possibly Akron-Canton to London or Toronto?

You could hold the ruler out at arms' length and stand just far enough from a window to fit the ruler (visually) inside the frame. Measure the distance from your eye to the window, and the width of the wondow and trig it out. Tangent (Window width/distance) to the get the angle of the whole ruler. From there divide by 12 to get the degrees per inch. Or go to 10 inches worth of ruler to math the math easier.

I did something similar with my thumb and was able to estimate the distance to a truck as 92 yards. The next night we used a laser range finder and got 93 +/-1.

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A Nerd can figure out how long it will take the original Enterprise traveling at warp 6.5 to travel from Regulus to Antares.
A Geek will think he can use that to pick up a girl in a bar.
A Dork knows he can't pick up the girl with it, but will hang around for hours anyway, just in case she asks.
She might. You never know.

But it's not like you can use it as a good "rule of thumb". (ba-dump-bump)

It must be aircraft, I have noticed the golden color.

Thanks again everyone.

I'm guessing polar satellite.

Any aircraft so high up it is point-like is going to be moving very slowly. You describe it as if is moving quickly, so it must be satellite in low-earth orbit.

Also, an aircraft reflecting sunlight would not be up so high earth curves, so it would not bop out of, and back into, earth's shadow so quickly.

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A shiny aluminum-colored aircraft can reflect the Sun's light
toward an observer on the ground for a couple of seconds,
just like the shiny flat antenna panels on Iridium satellites.
Planes are generally larger than Iridium antennae, but they
are also usually convex, so their flares are generally not as
bright or as short.

-- Jeff, in Minneapolis

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