Uranus, turning in Taurus

2026-10-11 · eclipticam v3w · night 2026-10-09 →
eclipticam v3w · 21 Sep to 9 Oct 2026 (9 nights) · 3.0° × 2.0°
Uranus from 21 September to 9 October, a quarter of a day per frame. Each of the 9 clear nights is laid into a rolling stack of the stars from the nights around it, and the gaps between them cross-fade. Blue dots are where it was measured on earlier nights, the grey line is the ephemeris. North is up, east to the left, so it is moving west. Brighter stars are labelled with their V magnitude; Uranus is V 5.7.

Uranus is the next planet out from Saturn and the one in from Neptune, and at magnitude 5.7 it is two magnitudes brighter than Neptune: 6 times the light. It is in Taurus this year, six and a half degrees from the Pleiades.

In the frame

Uranus only came into eclipticam's view on 21 September, near the top of the frame for the last quarter of an hour before dawn. Each night it is in view a few minutes longer: two hours by 10 October, and about five hours a night from November to early February. Opposition, when it is opposite the Sun and up all night, is about 23 November.

Of the 19 nights since it came into view, 9 were clear enough before dawn to stack. Uranus is in every one of them, between 5 and 46 sigma, and typically 1.3 arcminutes from where the ephemeris puts it. The early nights are only 5 or 6 frames; the clearest October mornings give 30 to 70.

Turning

Uranus stood still against the stars on about 10 September, and has been going backwards (westwards) since, as Earth comes round to overtake it. In the 18 nights here it moved 18 arcminutes, a little more than half a Moon.

That is barely longer than the smear of one exposure: in 60 seconds every star, and Uranus, trails about 14 arcminutes east to west at this declination. So far the walk is short, but it is speeding up. By early February it will have gone back about 3.5 degrees, and then it will stop and turn again.

Too small to see as a disc

Uranus's disc is 3.7 arcseconds across. An eclipticam v3w photosite covers 1.8 arcminutes at the centre of the frame, 30 times wider, so here Uranus is a point, like a star. What gives it away is that it moves.

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