Recent Events Beyond Earth

BIG BWACULL said:

Jupiters moon pic from THE AUSTRALIAN

Click to expand...

Quite by accident an astronomical method presented itself not too many years after Galileo's futile attempt, and, ironically, one of Galileo's earlydiscoveries in astronomy made the oportunity possible.

Galileo had bult a telescope, one of the first made , with which in 1610 he discovered the first 4 of Jupiers moons. (now up to about 28 known satellites and 12 more being checked out etc) . Like our own moon, each of them travels in an orbit around the planet, each to its own uniform amount of time called a period.

In 1675 Olaf Roemer, a Danish astronomer , measured the periods of Jupiter's moons, but he obtained different results when he measured them again several months later.

to understand what happened see Fig 1

Click to expand...

The only logical conclusion Roemer could draw was that this additional time represented the time to took for light from Jupiters moon to travel the extra distance across the diameter of earth's orbit . At that time the diameter of earths orbit was beleived to be about 172 million miles, instead of the correct 186 million miles, so that Roemer's data produced too low a value for the velocity. However Roemer's method is remembered as the first successful determination of the velocity of light.

Click to expand...

Jupiter possesses 28 known satellites, four of which - Callisto, Europa, Ganymede and Io - were observed by Galileo as long ago as 1610. Another 12 satellites have been recently discovered and given provisional designators until they are officially confirmed and named. There is a ring system, but it is very faint and is totally invisible from the Earth. (The rings were discovered in 1979 by Voyager 1.) The atmosphere is very deep, perhaps comprising the whole planet, and is somewhat like the Sun. It is composed mainly of hydrogen and helium, with small amounts of methane, ammonia, water vapor and other compounds. At great depths within Jupiter, the pressure is so great that the hydrogen atoms are broken up and the electrons are freed so that the resulting atoms consist of bare protons. This produces a state in which the hydrogen becomes metallic.
Colorful latitudinal bands, atmospheric clouds and storms illustrate Jupiter's dynamic weather systems.

etcetc
If Jupiter was hollow 1000 earths could fit inside etc

Click to expand...

Then felt I like some watcher of the skies when a new planet swims into his ken. - John Keats

Click to expand...

Ps the light reaching us from the sun is obviously about half that 1000 seconds old = 500 secs , call it 8 mins old.
i.e. when you see the sun rise, it actually rose 6 minutes ago

spooly74 said:

The Most Important Image Ever Taken

Click to expand...

http://en.wikipedia.org/wiki/Alpha_Centauri
Alpha Centauri is the closest star system to our own solar system at 4.37 light-years distant (about 41.5 trillion km, 25.8 trillion miles or 277,600 AU). Proxima Centauri, usually regarded as part of the system, is the closest star at 4.22 light-years distant.[2] Alpha Centauri's relative proximity makes it a logical choice as "first port of call" in speculative fiction about interstellar travel, which predicts eventual human exploration, and even the discovery and colonization of hypothetical planetary systems. These themes are common to countless works of science fiction and video games...

...Computer models of planetary formation suggest that terrestrial planets would be able to form close to both Alpha Centauri A and B, but that gas giant planets similar to our Jupiter and Saturn would not be able to form because of the binary stars' gravitational effects.[3] Given the similarities in star type, age and stability of the orbits it has been suggested that this stellar system may hold one of the best possibilities for extraterrestrial life.[4] However, some astronomers have speculated that any terrestrial planets in the Alpha Centauri system may be dry because it is believed that Jupiter and Saturn were crucial at directing comets into the inner solar system and providing the inner planets with a source of water. This would not be a problem, however, if Alpha Centauri B happened to play a similar role for Alpha Centauri A that the gas giants do for the Sun, and vice versa. Both stars are of the right spectral type to harbor life on a potential planet.

Click to expand...

"Each of these dots , smudges and smears
represents an entire galaxy,
each with millions of stars ,
each with the possibility of planets
each with the possibility of a civilisation.

This is what we see when we stare into a blank spot in the sky,
where nothing appears to be
This is the number of galaxies in nothing.
It is a picture of how small we are.
It is the most important image ever taken by humanity."

Click to expand...

An astute viewer (such as yourself) may have asked, "How can the universe be 78 billion light years across when the age of the universe is only about 13 billion years?"

Good question, how can something be larger than then distance travelled at the speed of light? Since light from the beginning of the universe has only had 13 billion years to travel (not 78 billion), then shouldn't the universe be only 13 billion light years across? That's a pretty intuitive thought.

But it doesn't take into account that the entire universe itself is also expanding. When a photon of light leaves it's point of origin, it does so at the speed of light, so in a universe that doesn't expand, a photon travelling for 13 billion years traverses 13 billion light years.

In a universe that DOES expand, all of the distance covered by the photon gets increased by a scale factor equal to the rate of expansion of the universe.

Since the universe has expanded some since it left 13 billion years ago, we have the apply a scale factor to account for the expansion. Keeping in mind that the universe is expanding continually, it's not stopping and starting, you have to do some calculus to solve the problem. When you do that, you come up with the size of the universe being 78 billion light years in radius, 156 billion in diameter.

Until recently, it was thought that the rate of expansion of the universe was slowing down. Recent measurements of the cosmic microwave background radiation have shown that the universe is actually accelerating, not slowing down.

So, what I was referring to in the video is called the Comoving Distance, or 'proper distance'. You can get a more detailed definition from the above link, but the comoving distance is a more accurate measure of the size of the universe because it takes into account the fact that the observer (us, the earth), is moving. It also takes into account that the universe has been expanding since its beginning.

Here is a another great article about the size of the universe to get more info.


Where Did Hubble Look?
So where exactly did the Hubble look to take the deep field images? Here is a photo with the region of sky I referred to in the video. As you can see, the area in the L-shaped outline is devoid of all stars. This was done on purpose. Astronomers didn't want any stars from the Milky Way galaxy to get in the way, so they selected this region.

It's important to realize that dedicating so much Hubble telescope time to this little project was a risky move. Time on this telescope is expensive, with very long waiting lists of astronomers who want to use it. It was risky because no one knew what they were going to see if they did this. I think taking the risk paid off, in a HUGE way.

This section of sky is located in the constellation of Ursa Major. This constellation lies outside of the disk of the galaxy so there are fewer stars to dodge by looking here. It was important that the image not be contaminated with foreground stars from our own galaxy. To me, that made the image all that more amazing, because every single point of light in that picture was sure to be a galaxy.

The irregular shape of the area outlined above corresponds to the fact that the complete Hubble deep field image was pieced together from three individual images taken with the telescope pointed in adjacent areas of sky. The detector on the Hubble Space Telescope employs a really old CCD that is 800x800 pixels square. To cover more area, they took many sets of images and moved the telescope around as they did so. Then they stitched them together to make the final image.

The diagram at left is a schematic of where the hubble looked for the 1995 Deep Field image. The constellation outlined is the Big Dipper, or Ursa Major the Great Bear.

I mention in the video that the Hubble stared into this region of sky for a little over 10 days. This was not done all at once. Many individual images were taken over the course of weeks, and then all of them were added together.

Adding images together like this is common in astronomical imaging. If you take, for example, 10 images with exposure times of 10 seconds each and then add them all together, it produces one image equal to an exposure time of 100 seconds.

The advantage of doing it this way has to do with the way images are produced by a CCD detector. CCD's produce more noise or 'grain' to an image if you just let them sit there collecting light. Less grainy images are obtained if you just add a bunch of shorter exposures together. With each image added, the light from the galaxies increases by the amount that the image was exposed, but the graininess increases by a lesser amount (the square root of the number of images for those technically motivated).

The result is an image that is sharper and has more detail.

To take the Ultra Deep Field, the Hubble Space Telescope looked in the direction of Orion, in the constellation Fornax. I'm afraid I don't have any pictures of this area yet, I'm still trying to find some, but the region in the animation on the video are accurate. It's just a little harder to see exactly where the Hubble was pointing when it took those pictures.

By the time they took the second image that became the Ultra Deep Field, the Hubble had been outfitted with an infrared camera called NICMOS, a 256x256 pixel camera that allowed them to see even more galaxies.

They also imaged using both cameras for a little longer, over 11 days this time, to produce the Ultra Deep Field. That image represents the farthest we have ever seen into the universe. Keep Looking Up!

Click to expand...

Length decreases as speed increases (Contraction of Length)
at 90% speed of light your dimension in the speedwise direction (whether approaching orleaving the observer) would be halved , L' = L sqrt (1-(V/c)^2)

There was a young fellow named Fisk
Whose fencing was exceedingly brisk;
So fast was his action
the Fitzgerald contraction
reduced his rapier to a disk.

Click to expand...

Mass increases with velocity
m' = m / sqrt(1-(V/c)^2)

It is ironic that when people attempt to decrease their mass with vigorous exercise such as running, - relativity says that the faster they run the greater they weigh - (to another observer) - by running at 15mph , a 300 lb man will increase in mass by 0.000 000 000 001 oz.

Click to expand...

Addition of velocities
northbound train approaches station at 100kph
and southbound train approaches station at 100kph
their relative speed is 200kph
(at these speeds , Vab is approx = Va + Vb)

BUT
if northbound train approaches station at 200,000kps
and southbound train approaches station at 200,000kps
their relative speed (as seen by the driver of either train) is NOT 400,000kph (because that would mean a relative speed greater than the speed of light)
it is Vab = (Va + Vb) / (1+ (Va.Vb/c^2) = 277,000kps
(always <300,000kps, the speed of light)
i.e. it is not possible for something to travel faster than the speed of light with respect to any other possible observer anywhere.
i.e. Light will always travel at the 300,000 kps relative to THE OBSERVER
and nothing with mass is permitted to travel faster than that

Click to expand...

Max possible velocity (of something with mass relative to an observer) is c.
(in fact less that c, because c inmplies infinite mass etc).
At c, you disappear, and faster than c you would go backwards.

There once was a lady called Bright
Who could travel faster than light
she went out one day
in a relative way
and came back the previous night.

Click to expand...

Time (and Clocks) are different for different observers
If we on Earth were to see Betelgeuse explode, and so also observers on Aldebaran, then
if the explosion happened 17 March, 2000 at Betelgeuse
then it would be seen at 17 March, 2250 on Aldabaran, and
17 March 2300 on Earth.

Click to expand...

Time, can be thought of as a fourth dimension -
"the reader is cautioned against concluding that time is an additional physical dimension in the sensse that it can be seen and felt like a material object. ... etc as per attachment

Click to expand...

2020hindsight said:

for discussion

Click to expand...

An astute viewer (such as yourself) may have asked, "How can the universe be 78 billion light years across when the age of the universe is only about 13 billion years?"

Good question, how can something be larger than then distance travelled at the speed of light? Since light from the beginning of the universe has only had 13 billion years to travel (not 78 billion), then shouldn't the universe be only 13 billion light years across? That's a pretty intuitive thought.

But it doesn't take into account that the entire universe itself is also expanding. When a photon of light leaves it's point of origin, it does so at the speed of light, so in a universe that doesn't expand, a photon travelling for 13 billion years traverses 13 billion light years.

In a universe that DOES expand, all of the distance covered by the photon gets increased by a scale factor equal to the rate of expansion of the universe. , etc

Click to expand...

After 15 million years of expansion, is the universe 15 or 30 million years "wide"??? My son asserts that because the expansion is one of space rather than matter, its total dimension = its time of expansion. This logic escapes me. If is is "expanding," surely it is doing so in all directions at once, thus yielding, to my (admittedly fallible) logic the necessity of its "furthest limits" moving diametrically away from each other. I.e., being two years separated in one year's expansion. Am I confusing time and distance here?

Click to expand...

Note that in the above paragraphs I have been careful to use the term "observable Universe" rather than Universe. The Universe itself, or the maximum amount of space that we will eventually be able to see given an infinite amount of time, may well be infinite. In quoting a size of the Universe we infer how far we can see in one direction (15 billion light years), and how far we can see in the other direction (15 billion light years) and add the two to get a size (30 billion light years). An age of 15 billion light years in each direction therefore leads us to infer that we are at the centre of a sphere with radius 15 billion light-years, and hence that the Universe is 30 billion light-years "across". The trick, however, is that because the Universe is homogeneous and isotropic, every observer must measure a size of the Universe that is 30 billion light years... even ones that are at the "edge" of our observable Universe! This means that either the Universe is sufficiently curved that space doubles back on itself (like on the surface of a sphere), or that the actual Universe is much larger than the observable one. We currently think that the latter possibility is the case.

Click to expand...

How big is the Hubble Ultra Deep Field image?
I think the Hubble Ultra Deep Field photo is amazing ... the implied numbers of galaxies and stars are mind-boggling, and hence my question.

The field of the HUDF is said to be about 1/10 the diameter of a full moon. To put the possibilities in perspective of a number that might be a little more comprehensible, how many photos that size (1/10 the Moon's diameter) would it take to cover the entire sphere of the sky?

Click to expand...

According to the Space Telescope Science Institute, the Hubble Ultra Deep Field has an angular size of 11.5 square arcminutes. That means that it would take 12,913,983 Deep Field images to cover the entire sphere of the sky!

Just for fun, let's calculate roughly how many stars that implies in the observable universe: The ultra deep field image has about 10,000 galaxies in it. If we assume that each galaxy has 100,000,000,000 (100 billion) stars, then the approximate number of stars in the visible universe is absolutely staggering: 123,000,000,000,000,000,000

123 quintillion stars! That's 123 billion billion. 123 million million million.

It is easy to get lost in these mind-boggling numbers. They are so overwhelmingly huge that the human mind cannot rationalize them. But at the very least, we can get a sense of things. The Ultra Deep Field shows us just how big the universe is and how small and fragile we all are.

Click to expand...

Max possible velocity (of something with mass relative to an observer) is c.
(in fact less that c, because c inmplies infinite mass etc).
At c, you disappear, and faster than c you would go backwards.

There once was a lady called Bright
Who could travel faster than light
she went out one day
in a relative way
and came back the previous night.

Click to expand...

2020hindsight said:

Now personally I don't have a clue what he's talking about , scaling factors etc (at least scaling factors large enough for 13 and 78 to "work", one being six times the other, etc ??
Maybe someone else out there does ?

Click to expand...

Model analogy

Ant on a balloon model
The ant on a balloon model is a two-dimensional analog for three-dimensional metric expansion. An ant is imagined to be constrained to move on the surface of a huge balloon which to the ant's understanding is the total extent of space.
At an early stage of the balloon-universe, the ant measures distances between separate points on the balloon which serves as a standard by which the scale factor can be measured. The balloon is inflated some more, and then the distance between the same points is measured and determined to be larger by a proportional factor.
The surface of the balloon still appears flat, and yet all the points have appeared to recede from the ant, indeed every point on the surface of the balloon is proportionally farther from the ant than earlier in the life of the balloon universe.
This explains how an expanding universe can result in all points receding from each other simultaneously. No points are seen to get closer together.

In the analogy, the two dimensions of the balloon do not expand "into" anything since the surface of the balloon admits infinite paths in all directions at all times.
There is some possibility for confusion in this analogy since the balloon can be seen by an external observer to be expanding "into" the third dimension (in the radial direction), but this is not a feature of metric expansion, rather it is the result of the arbitrary choice of the balloon which happens to be a manifold embedded in a third dimension.
This third dimension is not mathematically necessary for two-dimensional metric expansion to occur, and the ant that is confined to the surface of the balloon has no way of determining whether a third dimension exists or not.
It may be useful to visualize a third dimension, but the fact of expansion does not theoretically require such a dimension to exist.

This is why the question "what is the universe expanding into?" is poorly phrased. Metric expansion does not have to proceed "into" anything. The universe that we inhabit does expand and distances get larger, but that does not mean that there is a larger space into which it is expanding.

Click to expand...

lakemac said:

This explains the theory of my belt perfectly...

Click to expand...

There is some possibility for confusion in this analogy

Click to expand...

the ant that is confined to the surface of the balloon has no way of determining whether a third dimension exists or not.

Click to expand...

2020hindsight said:

lakemac - When you're young you pass thriough the light years,
then as you get older, you move into the heavy years

and maybe also:-

one thing's for sure, when the balloon goes bang, that ole ant is gonna look like he's discovered the fourth and maybe the fifth dimension as well - "Ant", by Pablo Picasso.

Click to expand...

yogi-in-oz said:

So, given that the sacred mathematics and geometry has been around for a couple of millenium and the planets are
still orbiting at EXACTLY the same rate, then we can make
better use of the cosmic clock ... for trading purposes.

Even now, we are only just scratching the surface of this
stuff, but we should be really thankful to those pioneers
in sacred geometry, that made the concept of astrotrading,
possible ..... pioneers like Pythagoras, Sepharial, Dow-Balliett,
Johndro and Gann, too .....

Click to expand...

yogi-in-oz said:

So, given that the sacred mathematics and geometry has
been around for a couple of millenium and the planets are
still orbiting at EXACTLY the same rate, then we can make
better use of the cosmic clock ... for trading purposes.

Click to expand...

The cosmos is 13.7bn years old but the stretching of space with its expansion after the Big Bang means that simple distance measurements do not apply.

This means that radiation reaching us from the earliest Universe has been travelling for more than 13 billion years.

But the assumption that flows from this - that the radius of the Universe is 13.7 billion light-years and that it is 27.4 billion light-years wide does not follow.

Try to imagine the Universe a million years after the Big Bang. Light travels for a year, covering one light-year. But at that time, the Universe was about a thousand times smaller than it is today meaning that one light-year has now become stretched to about a thousand light-years.

When this expansion is taken into account the Universe is bigger than it would appear to be.

Because of this stretching, radiation from the early Universe cannot be said to have travelled 78 billion light-years.

What it means is that the starting point of a particle of light, a photon, reaching us today after travelling for 13.7 billion years is now 78 billion light-years away.

And that is just the radius of the Universe.

Click to expand...