Astronomy: Uranus: on the boundary line – DAWN.COM

A genius does not belong to the house where it takes its birth; it belongs to the world which is its true home. That is where it belongs.

Uranus spins very fast on its axis, completing one spin in 17 hours. It is fast but nowhere as fast as big daddy Jupiter, which revolves on its axis once in only 10 hours. And considering the sprawling diameter of Jupiter, this is several times faster than Uranus.

The one stunning aspect is the fact that it has an ocean of water 8,000km deep. (In comparison the deepest portion of an ocean on the Earth is a measly 35,000 feet, or 10 km deep! Marianas Trench is the place, in the north-west Pacific Ocean which came about as a result of movements in Plate Tectonics, over-lapping one another).

That it seems incredible is remarkable enough. One more surprising reality is that the core here is as large as the whole of Earth, releases no heat at all. Enigmatic, indeed! Perhaps this is the reason why it is the coldest of all planets (-220C or 360F).

Also, it appears that the planet accreted (gathered nebular dust and gasses) somewhat later than the already-born Solar System a few hundred million years or a billion years or so later. A confirmation is awaited yet! Over 85 per cent of the atmosphere is molecular hydrogen and 12pc is helium, and methane in traces. So it appears blue-green because methane absorbs red colour (virtually eats it up).

The presence of 27 moons makes it heavy on traffic. Most moons are average-size asteroids: flat, irregular and pock-marked that is nothing except broken hills. They have survived because they orbit the mother planet rapidly and craftily save themselves from plunging into it. You never know, some are only captured asteroids that happened to loiter nearby and got trapped. The largest moon is Titania, with a diameter of just 1,600km, others are much smaller. Like any moon they, including Oberon, the second largest, are full of craters.

As far as any geological activity such as earthquakes are concerned, these moons are largely dormant, and as such, sleepy places if anything. They appear to have frozen in time. Much, in fact all we know about Uranus is courtesy the visit of Voyager 2 in 1985-86. A few of its moons have been spotted by many Earth-based astronomers, which is incredible, but nothing more. The remaining moons became visible when Voyager-2 closed in on Uranus.

Surprisingly, Uranus, like Venus, rotates in retrograde direction which is contrary to all other planets. This is another guess (hazardous, as it is) that this planet flew in from elsewhere in the course of the early universe; as you are aware, and joined the fray. More than four times larger than the Earth in diameter, its mass is 14.54 times more, thereby the escape velocity of 22km/second, very high compared with Earths 11.2. But on account of its great distance from the Sun (19.18 AUs to Earths 1) the orbital velocity of Uranus is 6.81 km/sec to 29.79 of the Earth. You are surely aware the nearer a planet is to the Sun the faster it has orbital velocity.

With Uranus lying at a great distance from the Sun, it does not have to rush because of decreased gravity of the Sun. Also it has a great deal to cover, requiring over 84 years to go around once. For Uranus to move (equal to) one full width of the full moon in the sky it takes 44.4 days, or say degree of sedate movement. Lazy, isnt it. It is another matter that the gravitational tug of Neptune and the tiny moons affects the giant who himself is not a bully, but is obliged to wobble a bit. But I suppose that it is accustomed to this, as you would be in four billion years time!

The Lone Ranger of the Solar System, playing safe lounging near the edge of the Solar System has strayed far out towards the end of the playing field, seems to be partying alone, way away from the madding crowd. Quite a recluse yet happy to be there, groggy, yet there!