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Message: <blockquote data-quote="Aexalon" data-source="post: 5411855" data-attributes="member: 16283">Any planet near enough to its star to orbit it in 24h would have to be very large to ever be visible to even the trained eye from your tidally-locked world. Additionally, it would be incapable of causing an eclipse, on the count of being too far away from your home world, and too close to the star. Interplanetary eclipses (or rather, <a href="http://en.wikipedia.org/wiki/Astronomical_transit" target="_blank">transits</a>) are typically difficult to observe without mechanical aid (filter glasses or solar projectors).A moon with a period of 24h is somewhat more feasible, but still tough to explain away. E.g. to have the Earth's moon orbit in that period, you'd have to move it almost 10 times closer than it does now. it'd shine 80 times brighter in the sky, and (probably most importantly) have a smaller eclipse path than our moon does (moving the moon closer increases its <a href="http://en.wikipedia.org/wiki/Umbra" target="_blank">umbra</a>, but shrinks its penumbra). Finally, a moon that close would interfere with the tidal locking between the planet and the sun, which was your initial premise. So, imho, a moon is out too.My best guess for an easily-witnessable astronomical phenomenon with a period of 24h, would be the orbit of a self-luminous <a href="http://en.wikipedia.org/wiki/Companion_star" target="_blank">stellar companion</a> around the primary star. This companion could be of similar size (reduce the size of the primary as to not cook your planet, but you already did that so your planet could be close enough to tidally lock in the first place, right?), a <a href="http://en.wikipedia.org/wiki/Failed_star" target="_blank">failed star</a>, or it could be a <a href="http://en.wikipedia.org/wiki/Stellar_remnant" target="_blank">stellar remnant</a>, e.g. a <a href="http://en.wikipedia.org/wiki/White_dwarf" target="_blank">white dwarf</a>. Brown or white dwarves suffer a bit from the same problem as your initial planet idea (still a bit difficult to observe), so my final recommendation has to go to placing your tidally locked star in orbit of a pair of <a href="http://en.wikipedia.org/wiki/Red_dwarf" target="_blank">red dwarf stars</a> (which would very likely be tidally locked with each other as well).</blockquote>

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