The natural Navigation: The Right Course, Naturally

Happy Equinox All!

At nine minutes past three this morning, GMT, the sun was overhead the equator.  To celebrate, here are a few things that you may or may not know about the equinox. Only one of them is not true.

The sun will rise due east and set due west for everyone today.

The direction (bearing) of sunrise and sunset changes by more each day at this time of year than at any other time.

On the December side of the equinoxes the sun is always overhead the southern hemisphere, on the June side it is always overhead the northern hemisphere.

Everyone on the planet shares an equal length day and night on the equinoxes.

Satellites that appear stationary and stay over the same spot on the Earth’s surface are called geostationary or geosynchronous and they remain in orbit over the equator. As the sun passes over the equator…

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For much of the UK, tonight promises to be a good night for some stargazing. With a bit of luck the only clouds for many will be from our breath. The moon, which is four days off full, will outshine many of the stars but should not spoil the party.

If the sky is clear we will get a very good view of Mars in the east in the early evening. Sitting between the constellations of Leo (easy to find) and Cancer (hard to find), it will be rising about thirty degrees north of east at dusk and pass through due east at 8.30pm. By then Orion, below the high moon, will have moved to occupy a large part of the southern sky. If you follow Orion’s belt down to nearer the horizon then low in the southeast you will see the brightest star of them…

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It is the morning after the equinox and not a bad one either. The sun rises due east on the equinox, but the daily difference is at its greatest at this time too so we have already moved north of east.

In this picture the horizon is well above sea level because of the hill, so we have to bear in mind that the angle the sun makes to the horizon will be 90 degrees minus our latitude, ie. our colatitude.