Caption: An artist's conception of exoplanet Upsilon Andromedae d viewed from from just above a hypothetical blue-white habitable moon.

Features:

1. Original caption: "Upsilon Andromedae d lies in the habitable zone of star υ And A. It is possibly a class II planet (Sudarsky classification) which means that would be too warm to form ammonia clouds. The shown clouds on Upsilon Andromedae d (NOT the hypothetical exomoon) are made up of water vapor which are white in color rather than the characteristic yellow-reddish clouds of Jupiter and Saturn." (Slightly edited.)

2. Upsilon Andromedae d orbits Upsilon Andromedae A: it has mass 3.75(54) M_Jup (debatable?), mean orbital radius 2.54(15) ± 0.15 AU, and orbital period 1276.46(57) days.

3. Upsilon Andromedae d is a Super-Jupiter, and probably cannot support life (more pedantically, life as we know it).

4. If sufficiently large moons (i.e., exomoons) of Upsilon Andromedae d exist, some of them may be in habitable zone (defined as being able to support liquid water on their surface). The image illustrates such a moon.

   Of course, being able to support liquid water does NOT mean there is liquid water and having liquid water does NOT mean there life as we know it.

   Actually, outside of the habitable zone there can be subsurface liquid water and perhaps then life as we know it. It is likely that Jupiter's Galilean moon Europa has subsurface liquid water, and so may have life as we know it---but people seem to keep finding reasons to rule that out.

5. No exomoons have yet been discovered for certain circa 2024. There are candidates and probably soon there will be confirmed discoveries.

6. Almost all exomoons that could be life-supporting must be tidally locked to the host planet. Thus, the planet would stay at nearly the same place in the sky relative to the ground as viewed from any location on the near-side of moon (near relative to the planet) and would NOT be seen at all from most of the far-side (far relative to the planet).

   If such a moon orbited nearly in the planet's orbital plane (which seems likely given the ordinary nebular hypothesis), it could have daily eclipses of the parent star. Thus, the near-side of the moon could have an ordinary night and an eclipse "night" every day.

   In any case, the everyday celestial spectacle on the moon would be quite different from that of the Earth.

7. Speaking of exomoons, yours truly, via time travel, contributed Zartlich Twelver to the Golden Age of Science Fiction (c.1938--c.1960). You can find it in old scifi anthologies if you really, really try---somewhere between Isaac Asimov (1920--1992) and Olaf Stapledon (1886--1950).