Tuesday, July 25, 2017

Again Astronomy

The nice, warm weather we're having at this time inspired me to take another picture from my very limited view of the sky here at our house. We're located close to Metrotown (lots of light pollution) and our horizon is blocked by high-rise buildings and close-by trees.

The original image of M13 - the fuzzy "star" at the middle right.

The cropped and enhanced image of M13

The original fainter image at the top, showing a little fuzzy patch, is a picture of the globular cluster M 13 in the constellation of Hercules. Exposure was 30 seconds, ASA 800. This "source image" was taken with a 200 mm lens coupled to a 2x Barlow lens, making the combination equal to a 400 mm lens. The effective f-ratio was f 8.

The close-up is an enhanced image of M 13. You can see that the source image contains a lot of hidden detail. The camera used is a Canon 60Da, the source image is in "Raw" format, which preserves much of the detail captured in the image. The detail can be extracted with appropriate graphics software (I used Pixelmator and Preview for this purpose). 

Click on the images for a larger view.

We call our galaxy the "Milky Way" because we're inside it and it appears to us as a "stripe" of stars in the sky so numerous and faint that they melt together to look like "spilled milk". The globular clusters surround our otherwise "pancake-shaped" galaxy in a kind of sphere centered on the core of our galaxy. Other galaxies also have globular clusters. Globular clusters are considered to contain some of the oldest stars in our galaxy. There are estimated to be somewhere between hundred thousand and a million or so stars in each globular cluster. You can see a detailed picture in my previous post regarding M53, another "local" globular cluster (https://penmachinedad.blogspot.ca/2017/07/this-is-why-hubble-space-telescope-hst.html).

Wikipedia describes them like this: A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. Most globular clusters in our galaxy show a lack of O and B type stars, an indication of their great age. The globular clusters in the Milky Way are all estimated to be at least 10 billion years old and therefore contain some of the oldest stars in the galaxy. A typical galaxy may contain up to a few hundred globular clusters; our galaxy, the Milky Way, has somewhere between 125 and 200 globular clusters orbiting the galactic center. Most globular clusters are found in the large spherical halo of a galaxy.

My very modest photographic effort gives you a bit of an idea about all this. It's amazing what "every-day" digital cameras can do.

Saturday, July 22, 2017

This is why the Hubble Space Telescope (HST) exists.

Astronomers are constantly looking to get finer detail about the universe, in order to better understand  it's evolution. We are also trying to find "life as we know it" elsewhere, both on  planets and moons in our own solar system, and other planetary (exoplanet) systems. Traces which could be attributed to "life" are very hard to detect, and this effort requires all the details we can possibly gather. 

Optical and radio telescopes, underground particle, cosmic radiation, and gravitational wave detectors, and other ingenious devices constantly collect, and highly trained people analyze these data to come to some more detailed conclusions about the answers to these endeavours.

One of the major steps in acquiring more detailed information occurred when the Hubble Space telescope started collecting data in 1990. So far, it has sent back more than 1.3 million images, according to NASA. I don't think that any telescope on Earth has done so.

Below is an image I acquired via the half-meter remote-controlled slooh.com telescope on the Canary Islands, and also downloaded a picture of the same globular cluster from the Hubble Space Telescope site.

The slooh.com telescope is of a size which many amateur astronomers also have in their own, private observatories. The HST is a larger telescope which orbits Earth, its mirror is 2.4 meters across. The difference in the details is obvious. The slooh.com telescope would show more detail if it were placed in orbit as well but not nearly as much, because of its smaller size. The reason for space-based telescopes is that this does away with all the interference caused by the Earth's atmosphere and man-made light and other pollution.

There are now other types of telescopes in space, most of which are dedicated to collecting data at wavelengths which are blocked from the surface of the Earth (ultraviolet, x-rays, deep infrared, certain radio frequencies, etc.).

All of this so that more details about the universe can be obtained.

M 53 imaged through a slooh.com remote-controlled telescope

M 53 as seen by the Hubble space telescope, also remote-controlled 

Monday, July 17, 2017

Space is impressive

The Whirlpool galaxy
(click on image to enlarge)
 I took this image through a remote-controlled slooh.com telescope on the Canary Islands. It can be seen as a small nebulous patch through binoculars.

Charles Messier, an astronomer who was an avid "comet hunter", generated a catalog of astronomical objects which, at the time and using rather smaller telescopes, could be mistaken for comets, because they appeared as faint and nebulous patches, just as comets do when they are far from the sun.

Charles Messier (Wikipedia)

These patches are listed from M1 to M110 in Messier's Catalog, and the Whirlpool galaxy is listed as M51. Messier did not recognize its shape. This spiral galaxy is about 25 million light years distant. The bright patch shown above M51 is what looks like the core of another galaxy (called a Seyfert galaxy), which seems to interact gravitationally with M51. This companion galaxy is listed in the NGC catalog as NGC5195. It was discovered in 1781 by Pierre Mechain and does not appear in Messier's catalog, although some astronomers list the pair as M51A and M51B.

The spiral structure of M51 was discovered in 1845 in Ireland by William Parsons (3rd Earl of Rosse) by means of a then giant 1.8 m reflecting telescope, called the Leviathan of Parsonstown - at the time the largest telescope on Earth. M51 was not recognized as a galaxy, separate from our own galaxy (the Milky Way), until Edwin Hubble (the Hubble Telescope in orbit around Earth is named in his honour) determined the distance of it. This distance puts M51 far outside the Milky Way and makes it a little more than one third as large. That still means that it probably contains about 150 billion stars. Edwin Hubble also determined that the universe is expanding, with far-reaching effects on cosmology and our general understanding of the evolution of the universe.

We know now of billions of galaxies - as numerous as the stars in our Milky Way. The Hubble Space Telescope shows that galaxies appeared very early in the existence of the Universe.

Impressive indeed.