Showing posts with label cosmos. Show all posts
Showing posts with label cosmos. Show all posts

Tuesday, February 16, 2016

February night sky, 2016. Planets galore.

 

If you watch the night sky in this month of February this year, you will get to see a rare sight. Early morning, around 5:30 am, you can catch five of the sun’s planets almost in a straight line. Like so.

stellarium-007

It is an awe inspiring sight. I took some pictures, but none of them capture the beauty of this spectacle accurately. You will be able to see Mercury, Venus , Saturn, Mars and Jupiter. Jupiter rises in the east around 10pm itself. You will be able to see a very bright dot in the east which does not blink at all.

Sunday, July 19, 2015

Apollo 11 - 46th anniversary

 

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Sadly, no one is talking about this.

 

 

 

Twelve of these astronauts walked on the Moon's surface, and six of those drove Lunar Roving Vehicles on the Moon. While three astronauts flew to the Moon twice, none of them landed on the Moon more than once. The nine Apollo missions to the Moon occurred between December 1968 and December 1972.

 

 

Forty six years ago today, Neil Armstrong and Buzz Aldrin became the first two people to walk on the Moon, and Armstrong snapped this iconic photo of Aldrin (and of himself, too—that tiny little astronaut reflected in the visor is Armstrong). But it wasn’t until today that Aldrin finally gave it the perfect caption.

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Strange facts:

 

1.You would expect that when NASA asks you to be the first man to walk on the Moon that they would consider the possibility of things going wrong. Well for Neil Armstrong he couldn’t afford the life insurance policy for an astronaut. However, along with Michael Collins and Buzz Aldrin he wasn’t alone. All three astronauts of the Apollo 11 mission decided to create a plan of their own to support their families if something bad was to happen. Before the Apollo 11 mission in July 1969 when all three astronauts were in pre-launch quarantine, they signed hundred of autographs and sent them to a friend. If anything was to happen to the astronauts during their mission, the entrusted friend was to send the autographed memorabilia to each of the astronaut’s families. This way they could make some money by selling the signatures of the Apollo 11 crew.

image-of-Armstrong-in-LM[1]

Neil Armstrong can smell the moon dust after the first moonwalk. (Image credit: Buzz Aldrin/NASA)

2. One thing that surprised the astronauts who visited the Moon was the strong odour of the lunar dust which they were only able to smell when they got back inside the Lunar Module. While conducting experiments on the surface of the Moon the astronauts’ spacesuits gathered the moon dust in the creases of the suit, once the crew returned to the LM and removed their helmets the dust got everywhere even on their hands and faces (some astronauts even tasted it). After coming into contact with oxygen for the first time inside the Lunar Module, the four billion years old moon dust produced a pungent smell. As most of the astronauts had a military history they could compare the aroma to that of gun powder. Neil Armstrong described the dust’s scent as similar to to wet ashes in a fireplace. This distinct smell remains a mystery as moon dust and gun powder have no similar compounds and the exact explanation remains unknown.

image-of-a7-l_eva_diagram[1]

Suit for a moonwalk (Image credit: NASA)

3. There’s no doubt that the people behind the Moon missions were smart and skilled. The kind of expertise required seems beyond our general understanding. The spacesuits that the astronauts wore in the Apollo 11 missions were made by little old ladies, a bit like the ones in the Shreddies advert. NASA approached the International Latex Corporation (ILC) to produce a suit alongside the aerospace company Hamilton Standard. However Hamilton Standard became wary of the ILC and designed their own suit which after being submitted to NASA was refused. Hamilton Standard blamed the ILC causing the fashion company to lose their contract.

However, that wasn’t the end of the International Latex Company as a few years later NASA advertised a competition for a new suit. A handful of retired ILC employees saw their chance and broke into their old offices, stealing back their original suit designs that had previously been overlooked. After a lot of hard work the employees submitted their design to NASA who were impressed. They choose the ILC’s suit as the competition winner and deciding that Hamilton Standard would provide the oxygen tanks for the suit which we can only imagine may have been a little awkward given their previously rocky relationship.

Since their success with the original space suit, the ILC has supplied NASA with numerous items for space exploration. Along with the new next generation Z-1 suit and the Extravehicular Mobility Unit (EMU) suit used on the International Space Station, the ILC also designed the airbags that enabled Spirit and Opportunity, the two Mars rovers, to land safely on the Martian surface.

4. As you can imagine, in the microgravity of space, there are a few things you would have great difficulty with. I’m not talking about things like typing with those thick gloves or attempting to get dressed when one sock wants to head left and the other is determined to go right. Well as you can imagine everything in microgravity floats and when I say everything I mean everything…therefore going to spend a penny in space is not easy.

Nowadays astronauts staying in the International Space Station have a specially designed toilet that they can seatbelt themselves onto whilst a suction device can aid them with any waste disposal. However during the Apollo 11 mission, the solution to this all natural issue hadn’t really been solved yet and one astronaut in particular spent the entire mission on tablets that stop diarrhoea just to combat the problem. Michael Collins said himself that ‘The drinking water was laced with hydrogen bubbles’ which produced “gross flatulence…resulting in a not so subtle and pervasive aroma which reminds me of a mixture of wet dog and marsh grass.” He wrote about this in his autobiography, Carrying the Fire: An Astronaut’s Journey (1974), and I’m pretty sure it wasn’t the most pleasant memories of the crew’s trip to the moon as they were crammed together in the Command Module for three days.

5.When the Apollo 11’s Eagle Lunar Lander was separating from the CSM Colombia there was a loud pop, a bit like the noise of a champagne bottle being opened. This was because the cabin in the LM hadn’t been fully compressed before the separation. Some claim that this minor fault actually pushed the LM four miles off from where it was originally supposed to land.

Image-of-AS11-40-5868[1]

Aldrin climbing down the ladder. He was careful not to close the hatch. (Image credit: Neil Armstrong/NASA)

6. When Neil Armstrong and Buzz Aldrin were heading out to explore the Moon they both had to remember not to fully close the door on the Landing Module behind them. The door was closed to prevent heat escaping from the cabin but not completely in case any the cabin  was somehow repressurised, which could make it difficult to get the door open. Aldrin and Armstrong joked about leaving the door open:

109:41:28 Aldrin: Okay. Now I want to back up and partially close the hatch. (Long Pause) Making sure not to lock it on my way out.

109:41:53 Armstrong: (Laughs) A particularly good thought. (Fromhttp://www.hq.nasa.gov/alsj/a11/a11.step.html )

Since then some websites have claimed there was no outside handle to get back in as the engineers back at NASA thought that the weight of a handle would affect the calculations of the descent so decided to leave the door without one! Well there was indeed a handle on the hatch complete with instructions!

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This diagram of the LM’s landing leg indicates that it was designed to compress up to 32 inches on landing.  Apollo 11 landed more softly than expected. (Image credit: NASA)

7. We all know the famous first words of Neil Armstrong as he stepped foot onto the moon, ‘That’s one small step for man and one giant leap for mankind.’ However Armstrong’s first step out onto the Moon wasn’t small at all, in fact Armstrong had landed the Lunar Module so gently that the shock absorbers hadn’t compressed. So his first step out onto the Moon was actually close to a four foot jump onto the lunar surface.

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Aldrin and Armstrong raise the Stars and Stripes rather too close to the LM. (Image credit: NASA)

8. Whenever you ask children what the astronauts who visited the Moon have left behind, the first hand up in the room always mentions the American flag. However, the fate of that flag is quite sad as it was later knocked over when Armstrong and Aldrin launched the Lunar Module back into lunar orbit to join with Collins in the Command Module. After Aldrin hit the button to begin the launch he looked out the window and watched as the infamous flag was blasted away with the rest of the material left behind on the lunar surface.

9. As you can imagine, the first men to land on the Moon was a global event, everyone that could, would be watching. Due to this, NASA asked the astronauts on Apollo 11 not to engage in any religious activities that could offend, insult or isolate the rest of the world. However, Buzz Aldrin felt the opportunity was too great to let pass by. Therefore once Armstrong and Aldrin had landed safely on the Moon and were waiting to take their first steps, Aldrin radioed back to Earth asking anyone who was listening to reflect on that moment in history. Aldrin gave thanks for the opportunity and produced a small flask of wine and a piece of bread which he then consumed whilst reading from the Gospel of John. From that moment Buzz Aldrin then became the first and so far the only person to participate in the Christian ritual of Communion on the Moon. Neil Armstrong watched on in respect but never participated.

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The front section of the LM’s interior. The banks of circuit breakers are to the left and right (Image credit: NASA)

10. After gathering some Moon samples, taking some pictures and raising the American flag, Neil Armstrong and Buzz Aldrin returned to the Lunar Module, only to realise that a switch on a crucial circuit breaker had broken. This particular broken switch left them without a way to ignite the engine, so they tried to sleep while the mission control team at NASA tried to find a way to repair it. Eventually Aldrin decided that enough was enough and jammed his pen into the mechanism creating a make-shift switch. Surprisingly enough this quick-fix worked and launched both Aldrin and Armstrong off the lunar surface.

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The leaden hand of bureaucracy or a joke? (Image credit: US Government)

11. As the Apollo 11 team arrived safely on the Earth, the crew were brought to Hawaii. Despite being the three most famous men at the time, as they had just landed on the Moon safely and returned, they were still asked to fill out a customs and declarations form at security. As you can imagine, in the section asking “Departure From:”the Apollo 11 crew had to write “The Moon”.

Monday, June 16, 2014

The Disappearing Universe

 

“I realise now that I wanted to disappear. To get so lost that nobody ever found me. To go so far away that I’d never be able to make my way home again. But I have no idea why.” -Jessica Warman

When you lie down on your back on a clear, dark, moonless night, what is it that you see? If your vision is outstanding and observing conditions are just right, you’re likely to see not only a few planets and thousands of stars, but also star clusters, some faint nebulae, the plane of the Milky Way, and maybe even a distant galaxy or two.

Image credit: © Royce Bair of flickr, viahttps://www.flickr.com/photos/ironrodart/sets/72157627607005290/.

But when you start to look more deeply — beyond what you can see with your naked eye — you start to find that there’s an amazing Universe past our own galaxy, past the stars, clusters and nebulae of the Milky Way out there. What once seemed like faint, fuzzy, inconsequential smudges have since revealed themselves to be distant galaxies, or island Universes not so different than our own, consisting of anywhere from hundreds of millions to many trillions of stars.

And the Universe is full of them, with roughly as many galaxies in the part observable to us as there are stars in the entire galaxy we inhabit.

Image credit: Tony Hallas of Astrophoto.com, via http://apod.nasa.gov/apod/ap070719.html.

What’s perhaps surprising about these galaxies is that the farther away we find them, the faster they appear to be moving away from us. This was one of the most puzzling discoveries of the early 20th century, and it was finally put into order by Edwin Hubble (and, independently, Georges LemaĆ®tre) who realized that this was a consequence of living in an expanding Universe.

The resultant relation — that the farther away a galaxy is from us, the faster it appears to recede — is known as Hubble’s law. The only exceptions to this rule happen when a galaxy has been subject to an intense,local gravitational interaction, giving it what’s known as a significant peculiar velocity. But on the largest scales, Hubble’s law, or the velocity/redshift relation, shows itself incredibly clearly.

Image credit: Andrew Liddle’s Introduction to Modern Cosmology.

You might instinctively wonder, especially if you know about the framework of the Big Bang, whether this will continue forever or not? Hubble’s famous law was formulated all the way back in 1929, and for the majority of the 20th century, scientists were seeking the answer to that very question.

Image credit: retrieved from John D. Norton at University of Pittsburgh, modified by me.

You see, the Universe originated from a hot, dense, very rapidly expanding state. It was full of matter and radiation, and over time it expanded, cooled, and the expansion rate began to slow. In addition, gravitational imperfections grew into galaxies and clusters of galaxies, or shrank into great cosmic voids.

From a time billions of years ago when the Universe was almost perfectly uniform, with no life, planets, stars or galaxies in it, we now have — on average — hundreds of billions of stars in each of hundreds of billions of galaxies, populating an observable Universe some 92 billion light years across. And it looks something like this.

https://www.youtube.com/watch?v=08LBltePDZw

Sure, the Universe started off expanding very rapidly, but it also started out with a tremendous amount of matter-and-energy in it. Over time, gravitation slowed the expansion rate down. And things are still expanding… for now.

But that’s our past history. What about the future?

You can imagine — as most scientists did for most of the 20th century — three possible scenarios:

  1. Gravity wins. If there’s enough matter-and-energy, then gravitation could eventually overcome the initial expansion. The Universe will reach a maximum size where the expansion rate drops to zero, and then a contraction phase begins. Over enough time, the Universe will return to a hot, dense state, and ends in a fiery fate known as the Big Crunch.
  2. Expansion wins. If there isn’t enough matter-and-energy, then gravitation fails to slow down the initial expansion sufficiently. Distant galaxies will continue to recede away, and even though the expansion rate drops, it will never reach zero and will never reverse itself. Eventually, everything will be so far apart that it will end in a state where all its matter is arbitrarily close to absolute zero: the Big Freeze.
  3. The “Goldilocks” case. If the Universe had just one more proton in it, it would recollapse and end in a Big Crunch. If it had just one fewer proton, it would expand apart forever. But in a critical Universe, the expansion rate and gravity sit right on that edge. The expansion rate asymptotes to zero, but freezes at the slowest possible rate without recollapsing.

For a long time, we attempted to measure which of these three options described our Universe. Was it going to recollapse, was it going to “coast” forever, or was it the critical case?

Image credit: Pearson / Addison-Wesley.

Imagine our surprise when the data came in — just in 1998 — indicating that it was none of these options! Instead, the expansion rate isn’t going to keep dropping, but will asymptote to a finite, non-zero value.

This means that each and every galaxy, as it moves farther away from us, will recede faster and fasterover time, appearing to accelerate away!

Image credit: NASA & ESA, via http://www.spacetelescope.org/images/opo9919k/.

In one sense, this is just the nature of the Universe, doing what it does by obeying the laws of physics. But in another, more thoughtful sense, this is incredibly depressing.

You see, in the three scenarios we had envisioned previously, if you left Earth in a rocket ship that could move at arbitrary speeds, you could always reach any galaxy in the observable Universe, given enough time. Sure, the more distant a galaxy was, the longer you’d have to travel to get there, but everything was reachable in principle, no matter how dim, faint or distant it was. Because gravity would decelerate the expansion rate over time, if you were dedicated enough, and traveled at a fast enough speed for a long enough time, you could inevitably run down anything in the Universe.

Image credit: Jean-Charles Cuillandre (CFHT) & Giovanni Anselmi (Coelum Astronomia), Hawaiian Starlight.

But not if our Universe is accelerating. If something is receding from us right now at more than 299,792.458 km/s — faster than light speed — and it’s accelerating too, how could anything reach it? Even a photon, moving at the speed of light, wouldn’t be able to reach such a galaxy. Instead, anything beyond that point will do something that cosmologists call red out, which means they’re sufficiently redshifted that anything we do today could never, ever reach them, and only the light they emitted in the past will ever reach us. We are already causally disconnected from them.

And one incredibly frightening thing is that any galaxy with a redshift bigger than about 1.5 (which is notthat big a number) is already gone.

NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI).

Consider an image like this: 10,000 of the faintest, most distant galaxies we’ve ever discovered. By measuring their redshifts, we can determine (going back to Hubble’s law) precisely how far away these galaxies are.

And as it turns out, about 40% of the galaxies in this image are already unreachable, even for a beam of light that left today. If we zoom in to this region of space and imagine what these galaxies look like as far as “depth” goes, as in the video below, we’d find that everything left in the image after about the 0:38 second mark has already redded out.

https://www.youtube.com/watch?v=wFkRCFvdtTw

And as the Universe continues on in time, more and more galaxies are redding out as the Universe continues to accelerate. With each second that goes by (on average) thousands of stars and their planetary systems cross that horizon forever, and leave our ability to reach them for all eternity. Of the hundreds of billions of galaxies (maybe even as many as a trillion) in our Universe today, only about 3% of them are still reachable. And every time a mere three years goes by, another one fades from our present reachability.

Image credit: Steve Bowers, via http://www.orionsarm.com/eg-article/48545a0f6352a.

We can always hope that some type of controlled wormhole, or spacetime-bending faster-than-light travel can save us, but there’s no evidence that such an innovation — despite our best science fiction dreams — can ever be practically realized. Until then, we’d better plan on starting our journey sooner rather than later.

Because the expansion marches on.

Readability — An Arc90 Laboratory Experiment

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