daylight saving time) at 40 [degrees] N latitude; Mercury at greatest elongation (maximum apparent separation
) from the sun (26 [degrees]).
They have statistically the same parallax distance and may be moving through space together, but their distance from us and their apparent separation
implies an unusually long orbit, on the order of 100,000 years.
are the brass tacks of double star observing, as a couple of famous examples will illustrate.
But what's really exciting is the apparent separation
between the two planets.
The orbital period of the pair is 167.5 years, and the stars will reach their maximum apparent separation
of 1.3" in the year 2040.
Doolittle says that in the late 1970s, when the white dwarf was near its maximum apparent separation
of about 11 arcseconds from Sirius, he and some other members of the Amateur Telescope Makers of Boston got an unusual chance to use Harvard College Observatory's 0.38-meter (15-inch) refractor.
This binary lies at a considerable distance from Earth yet still has a very large apparent separation
, indicating that the distance between the components must be huge--at least 600 billion kilometers!
The apparent separation
of the two stars is increasing, however, and last year I was finally able to catch a glimpse of the Pup with my 4.1-inch (105-mm) refractor on one night of exceptionally fine seeing.
Taking all this into account, computational wizard Jean Meeus finds that Polaris will be closest to the north celestial pole on March 24, 2100, with an apparent separation
of 27' 09".
The stars are about 23 parsecs (76 light-years) away, and their apparent separation
is currently 4.4[inches].