Tag: orbit

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]

First Man-made Object in Space – A Manhole Cover?

By Anupum Pant

Edit: The first man-made object to cross the boundary of space (100 km above the sea level, or the karman line) a Nazi German V2 rocket on October 3, 1942. – As mentioned by Scott and Adolf in the comments.

Background

Odd, I know. Teachers would say Sputnik was the first ever man-made object to orbit earth, but there is a slight possibility that Sputnik might not have been it – it could have been a humble manhole cover (not so humble, read on).

Back in the year 1956 (or summer of 1957, but definitely before the launch of Sputnik which happened on 4th October 1957), scientists at Los Alamos were learning to contain a nuclear explosion. To find out, they decided to do a much much larger version of the fire-cracker-in-a-can trick…
I’m not sure if they were doing it out of a desire to loft objects in space using a novel nuclear bomb propulsion, or it was something else, it sure was madness.

The mad experiment

In a 500 feet long and 4 feet wide vertical cylindrical tunnel, they put a nuclear bomb. The top of this tunnel was sealed using a 4 inch thick man hole cover (on steroids). The lid weighed about 2 tons! They were sure that even the 2 ton lid would blow off like feather due to the nuclear explosion. However, they weren’t sure on exactly how fast it’d travel up. To measure the speed, high-speed cameras were placed near the opening.

The bomb was detonated. Some say that the high speed cameras were only able to capture the image of the lid in a single frame. Which by the way could also contribute to an enormous error margin in the speed calculation. Nevertheless, the speed was of the lid at which it flew up in the air was calculated to be 41 miles per second – approximately 6 times the escape velocity! Never before had any man made objects moved at that speed inside the earth’s atmosphere. The lid went. It was never seen again. No one knows where it is now.

It’s highly likely that the lid was burned up and never reached Space. Or, may be it did reach some place and then dropped back. Again, must have got burnt during re-entry. Nothing can be said for sure.

Another thing that could have happened is that the lid went on and started orbiting the earth – highly unlikely, still. It’s probably still floating up there. And if things weren’t worse already, think of this – the first man-made object ever to orbit the earth was a manhole cover? Or, the fastest man-made object ever to travel inside the earth’s atmosphere was a manhole lid? Damn!

[Source 1] [Source 2]

The Sun’s Unusual Behavior – Seen from Mercury

by Anupum Pant

The sun – as seen from Earth

For most of us living on Earth (closer to the equator), the sun has followed a simple path throughout the years. It rises, goes up at noon and then sets for rest of the day. It is a simple straight line for the complete year.
For people living a little away from the equator, things get a bit interesting. There, the summer sun at noon is overhead, but the winter sun is low at noon, not overhead. It isn’t very easy for a person living near the equator to grasp this phenomenon well. You’ll have to go there and see for yourself. Or simply, the simulator at the end of this paragraph will help you understand it better.
At poles, the sun almost moves horizontally for many days. It keeps on making a horizontal circle around you. There, it is day for 6 months and night for the next 6 months. [Here is a sun path simulator for Earth]

However, nowhere on earth, things get as interesting as they get in the skies of Mercury.

The sun – as seen from Mercury

On Mercury, the sun appears to briefly reverse its usual east to west motion once every Mercurian year. The effect is visible from any place on Mercury, but there are certain places on its surface, where an observer would be able to see the Sun rise about halfway, reverse and set, and then rise again, all within the same day. It is indeed an unusual performance which isn’t easy for us Earthlings to digest. [See animation in the next paragraph]

Why does it happen?

Let us consider a simpler analogy – some planets (like Mars), as seen from earth, take a similar path. [see the animation for Mars’s path as seen from earth]

The planets, including Earth, all travel around the Sun in a continuous orbit. We can see them make their way across the sky in a straight line usually. However, every now and then a planet appears to turn around. After turning around, it appears to move back the way it came. This is called a retrograde orbit and is caused due to the difference in speeds at which the planets circle the Sun.

So, as we see Mars do a reverse from earth, a similar motion of sun is observed from the surface of Mercury.

[Apparent Retrograde Motion – Wikipedia]