The Largest Object in the Solar System

By Anupum Pant

On November 6th 1892, after being spotted by a British astronomer Edwin Holmes, comet Holmes was not seen again for several decades. Thus it came to be known as the lost comet. Out of the blue, more than 70 years later, the comet was again seen in the year 1964.

Now it is known that comet Holmes was captured by Jupiter several thousand years ago, and it never went back to the Kuiper belt. It is a Jupiter family comet. Every 6.88 years, the comet orbits the sun.

Even this year, on 27th of March, it was one of the most bright comets of the year. But it was something that happened back in the year 2007 which made it one of the most popular comets in the sky.

For a brief period, comet Holmes, which is also a part of our solar system, became the largest object in the solar system. Yes, even larger than the sun!

On November 9th 2007, the diameter of comet’s coma – a cloudy region surrounding the comet made up of very tiny shiny ice and dust particles – measured about 1.4 million km. The sun’s diameter rounded to the nearest hundred is estimated to be 1.392 million km. Agreed the coma wasn’t as massive as the sun, but the size of it did measure slightly more than the sun at that time.

It indeed is a great achievement to become the largest object in the solar system (for some time) for an object that is just a tiny mass of ice and dust that is only about 3.6 km wide.

That day, the cloud around it erupted due to a mysterious outburst which still puzzles scientists. Such outbursts have been seen in the past too and are thought to have been originated as a result of its collision with a meteor (or probably due to an internal steam eruption).

via [space]

The Tallest Mountain in Our Solar System

By Anupum Pant

Right here on earth there are really tall mountains. Mount Everest is the highest peak and then there’s Mauna Kea in Hawaii which is supposed to be the tallest. Yes, even taller than the Mt. Everest. To add to it, there’s one highest unclimbed mountain – Gangkhar Puensum – in Bhutan.

If we zoom out a little and put the whole solar system in our radar, things change. Mt Everest or even Mauna Kea are no where near the tallest mountains we have in our solar system. For instance, Olympus Mons, a shield volcano has, for a long time, been considered the highest peak in our solar system.

This is how it compares with mount Everest, for example. The peak of  Mount Everest measures 8,848 meters. It’s absolutely huge. And yet, Olympus Mons on Mars is about 2.5 times higher! It measures about 22 kilometres in height. This image clearly shows how it compares with our tallest and highest mountains…


And yet again, even Olympus Mons, which has had the title of the tallest mountain in our solar system for several years, is believed to be no longer the tallest one.

A recently discovered peak in a proto-planet called Vesta is probably now the tallest mountain in our solar system. However, since this one – Mount Rheasilvia – is estimated to be only a few 100 meters taller than Olympus Mons, it has not very clearly dethroned Olympus Mons. Still, the data is pretty solid and can be trusted.

Rheasilvia was a peak known to researchers since 1997. But it was in 2011, when the Dawn spacecraft passed it, the data became really clear.

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