Mercury at perihelion, seen from afar

Event Date: February 17th

Time: 02:33 (UT)

Brief

   For this evening, I will continue with the Mercury topic at greatest elongation, while very close to perihelion.  However, unlike yesterday, the image will only clearly indicate the latter scenario because...I will be showing it in orbit viewed from millions of miles away.  Okay, so you may be thinking that Mercury is already millions of miles from us, and of course, you are correct.  However, I am talking about our viewing point towards Mercury, being millions of miles from Earth!  I normally don't do this, since this blog is supposed to be a guide from viewing from the Earth.  However, since the 18.1º separation between Mercury and the Sun for greatest elongation is about 10º less than their greatest separation at aphelion, I thought that I would show one of the two extremes, taking advantage of the software's many neat features.  Take a look and notice that Mercury is in line with the perihelion marker.

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

  

Detailed

   Although there is no aphelion marker, slicing Mercury's ellipsoid-shaped orbit nearly in half starting at the perihelion marker, would have the "cutting line" go to almost the point of aphelion.  Notice now the Sun is clearly not centered, just as we are not centered in our Moon's orbit.  Hence, we and other planets ave perihelion/aphelion with the Sun, the same way that Earth and other planets have perigee and apogee with our and their Moons (satellites) respectively.

   Also, take notice of a very interesting galaxy that I labeled below Mercury's orbit.  I have not talked about this yet in my entries since I was not aware of it.  However, NGC 292--also known more commonly as the Small Magellanic Cloud--orbits the Milky Way!  I will talk more about it during an entry not long from now, when we "head home" to viewing from Earth; the galaxy is visible from there to the eye alone, so worth coming back to. In the meantime, as seen from far in space, it is 200,000 light years away, which is between (arguably) 10-15 times closer to us than the Andromeda Galaxy, featured in past entries.