Uranus at Opposition on 15th of October

Uranus will be well placed for observation, in the constellation Pisces. It will be visible for much of the night, reaching its highest point in the sky at around midnight local time.

This optimal positioning occurs when Uranus is almost directly opposite the Sun in the sky. Since the Sun reaches its greatest distance below the horizon at midnight, the point opposite to it is highest in the sky at the same time.

At around the same time that Uranus passes opposition, it also makes its closest approach to the Earth — termed its perigee — making it appear at its brightest and largest.

Image via Star Walk 2 app

This happens because when Uranus lies opposite the Sun in the sky, the solar system is lined up so that Uranus, the Earth and the Sun form a straight line with the Earth in the middle, on the same side of the Sun as Uranus.

In practice, however, Uranus orbits much further out in the solar system than the Earth — at an average distance from the Sun of 19.29 times that of the Earth, and so its angular size does not vary much as it cycles between opposition and solar conjunction.

On this occasion, Uranus will lie at a distance of 18.95 AU, and its disk will measure 3.7 arcsec in diameter, shining at magnitude 5.7. Even at its closest approach to the Earth, however, it is not possible to distinguish it as more than a star-like point of light without the aid of a telescope.

Credits: https://in-the-sky.org/news.php?id=20161015_13_100

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