Astronomy Fact On Mercury a day (the time it takes for it to spin round once) is 59 Earth-days. Its year (the time it takes to orbit the sun) is 88 days- that means there are fewer than 2 days in a year!
Notes about viewing ESVs:
When using lookangles, choose passes with high magnitudes; less than 6.0. ("Looks" are local time.)
Best viewing is when ESV is in Earth's penumbra; on map-solid line during night.
Dotted line on map denotes ESV is dark, in Earth's umbra (shadow).
Objects in orbit have to maintain a speed of at least 17,500mph, therefore ESVs traverse the sky noticeably different than aircraft.
ESVs appearing to blink are either tumbling rocket bodies, or spinning payloads with deployed solar arrays.
High-Eccentricity objects have a more ellongated orbit. Ground trace looks like a backwards C.
Regression-Ground traces will move West with each orbit due to Earth's rotation.