Caption: "Image of Uranus obtained in 2005 by Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST). The rings of Uranus, the southern collar, and a bright cloud in the northern hemisphere are visible." (Slightly edited.)

1. Images of Uranus are often blue bland. So it's nice to find an HST image with some interesting features.

   The blue color is a result of reflection of sunlight by methane (CH_4) (the main component of natural gas).

2. In small telescopes, Uranus appears as small bluish-green disk. That is all that William Herschel (1738--1822) saw when he discovered it in 1781.

3. Uranus is actually just barely visible to the naked eye and had probably been observed many times before being discovered as planet---which, of course, was Herschel's achievement.

4. The first recorded observation of Uranus was in 1690 by John Flamsteed (1646--1719) (see Wikipedia: Uranus: Discovery). Almost 20 other pre-disovery observations of Uranus were discovered over the 40 years after 1781 (see No-427).

   Actually, Uranus had probably been seen many times thoughout history without any taking any special notice.

5. The discovery of Uranus was during one of Herschel's greatest endeavors, a program to map the universe (No-399). The date was on 1781 Mar13 and he was using 6.2 inch reflector (No-399). Herschel knew it was NOT a star since it showed a finite bluish-green disk as aforesaid. He thought it was a comet and he was NOT the first to call it a planet. Only over the course of a few months did the astronomical community determine it to be a planet. Uranus is the first planet discovered in historical times.

   By the by Herschel insisted his discovery was NOT accidental, but fortuitous, since he was doing an astronomical survey, and so was searching for astronomical objects and so would find them if they were there to be found????.

6. Herschel called the new planet Georgium Sidus in honor of George III (1738--1820, reigned 1760--1820), but outside his adopted homeland that was considered too Britannic and the world settled eventually on Uranus, the name of the mythical Uranus, the primordial Greek sky god.