Question

Let us pretend that you want to re-discover the dwarf planet Quaoar. a).  Given that Quaoar’s semi-major...

Let us pretend that you want to re-discover the dwarf planet Quaoar.

a).  Given that Quaoar’s semi-major axis is 43.6 AU and you need Quaoar move at least 3 arcseconds to observe that it has moved, what is the highest frequency you should visit the same patch of sky to “discover” Quaoar? Every night? Every three nights? Once a month? Show your math and make sure to factor in that there is only about 8 hours of dark time to observe every night… For reference, 1 arcsecond is 1/60th of an arcminute, and 1 arcminute is 1/60th of a degree. (Hint: for very small angular moves, you can treat Quaoar’s motion as a straight line.)

b).  Given how far Quaoar would have moved between nights, why did Mike Brown need to use the 48-inch Schmidt telescope with a 36 square arcminute field of view to find dwarf planets like Quaoar in the Kuiper Belt?

(b) Though Quaoar moves significantly every night in the sky, and henchence one would think that a moderate telescope would suffice for its observation, one has to note that it is a dwarf planet and we could detect it by receiving the sun-light reflected by it towards us.

In other words, being very faint source, one need a telescope with large enough objective lens so that it actually sees the source as faint as Quaoar. That is the reason Mike Brown needed a 48 inch Schmidt telescope to find the dwarf planet.

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