The Cosmic Microwave Background (CMB)

What is the CMB?

The radiation left from the early stages of the universe is called cosmic microwave background radiation. When the universe was at this early stage, it was soo hot that all atoms in the universe were ions. An ion is an atom that has positive and negative electrical charges. At this point in time the conditions of the universe may have been similar to that of a star; hot, dense and opaque allowing different atoms to pass through it.

Over time as the universe expanded, this gas cooled down. This ofcourse took several hundred thousand years. Radiation that was left behind from the big bang has been able to travel throughout the universe. As this early universe expanded, the radiation red-shifted to longer wavelengths and was therefore in a form to represent different temperatures. The spectrum of the CMB maintains the shape of a Blackbody spectrum. According to writer of http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html 

"Blackbody radiation refers to an object or system which absorbs all radiation incident upon it and re-radiates energy which is characteristic of this radiating system only, not dependent upon the type of radiation which is incident upon it. The radiated energy can be considered to be produced by standing wave or resonant modes of the cavity which is radiating."

The presence of CMB radiation with a Blackbody is a strong indication of the Big Bang theory. 

This above picture is a view of the sky after the foreground glow of the solar system dust has been extracted. This image is dominated by emission from interstellar dust in the Milky Way Galaxy. The two bright objects in the center of the lower right quadrant are nearby galaxies, the Large and Small Magellanic Clouds.

Source: Hubblesite.org

The COBE satellite 
The Cosmic Microwave Background Explorer was launched in 1989. Developed by NASA's Goddard Space Flight Center, its mission was to measure the infrared and microwave radiation from the early universe. COBE made some very precise measurements at different wavelengths. These measurements were from a few micrometer to 1 centimeter. 

 

The data on the graph above shows small dots, these small dots are the COBE measurement of the CMB at different frequencies. The X-Axis of the graph represents the frequency cycle per centimeter and Y-Axis represents the brightness of the frequency component. The uncertainty in each measurement is less than size of each dot. The left hand side of the curve that just begins to rise represents data points of a blackbody spectrum.  The above observation matches theoretical predictions of the Big Bang almost with perfection. So much so that there can be little doubt that one is seeing the radiation left behind from a hot, dense beginning from an earlier universe. Researches John Mather and George Smoot were awarded Nobel Prize for this work in 2006.

The above mapping shows the Northern and Southern galactic hemispheres,

Images of different regions of the hemispheres, the second image is of our galaxy. The galactic center is the middle bulged.

 

This graph displays the different magnitudes of the wavelengths from radio waves to X-rays and Gamma rays.

Image of CMB as produced by data collected byt he WMAP.

In 2001 the Wilkinson Microwave Anisotropy Probe (WMAP) made more accurate measurements of the CMB variations.  The above is much more detailed map of the structure of the universe.
In 2013, the European Space Agency (ESA) launched the Planck mission, which went one step further and obtained images in a much higher detail.

The image shows observations of the Cosmic microwave background (CMB) as observed by Planck. The image shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all future structure: the stars, galaxies and nebula's that we have today.

"Most galaxies are usually in a group close by. A neighboring is never too far away. But this galaxy, known as NGC 6503, has found itself in a very lonely position, at the edge of a strange empty patch of space called the Local Void.
The Local Void is a huge stretch of space that is at least 150 million light-years across. It seems completely empty of stars or galaxies"

Source: Hubblesite.org

Star V838 Monocerotis

Source: Hubblesite.org

30 Doradus Nebula, is a giant star-forming region

Source: Hubblesite.org

 
Early scientists predicted that, the early universe must have begun as a singularity and then expanded as radiation and elementary particles. However what do we mean when we say singularity?

According to the FreeDictionary a singularity is "a hypothetical point in space-time at which matter is infinitely compressed to infinitesimal volume"
This means matter which infinitely falls toward a negative value making it smaller than any real value.

The Big Bang theory is fundamental to our understanding of the universe. So far it has resisted any efforts made by researchers to prove it false, as the CMB provides evidence of the scenario of our early universe.

The above image shows the Nucleus of Galaxy Centaurus A.

Source: Hubblesite.org
Some of the crucial discoveries made by the COBE were:

• COBE revolutionized our understanding of the early cosmological structure.
• It measured and mapped the oldest light in the universe -- the cosmic microwave background. This was similar to seeing a baby picture of the universe.
• The cmb spectrum was measured with a precision of 0.005%.
• The results confirmed the Big Bang theory of the origin of the universe.
• The very precise measurements helped eliminate a great many theories about the Big Bang.
• The mission urged scientists into a new age of precision measurements, providing ground for new research into microwave background by NASA's WMAP mission and ESA's Planck mission, that latter provided much more detailed measurements.

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Goodbye for now and see you next time.

Pluto on the Horizon

NASA completed a historic mission of New Horizons to the Pluto system this month, which consisted of exploring Pluto and its moon's; Charon, Styx, Nix, Kerberos and Hydra. To get this mission approved it took around 14 years spanning from 1989 to 2003. 

Clyde Tombaugh discovered Pluto in 1930 at Lowell Observatory in Flagstaff, Arizona. In Tombaugh's time one could only determine Pluto's orbit and color. Pluto's orbit is 284 Earth years and is very elliptical. At perihelion, Pluto is closer to the Sun than Neptune. Pluto's orbit is locked in a 3:2 ratio with that of Neptune's.

In 1978, Christy & Harrington discovered Charon, Pluto's largest moon.  Pluto and Charon have a rocky core which is encapsulated with water ice mantle. They both are also tidally locked, each having a hemisphere that faces the other. 

Not much detail is known about Pluto, but the New Horizon's mission should shed more light in the coming months. Currently around 90% of the data is still aboard the space craft and yet to be transmitted back to NASA communications back on Earth.

 

http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/pluto.htm 

Pluto's surface is an icy mix of frozen water, carbon dioxide, nitrogen, methane and carbon monoxide. Pluto also has a very thin atmosphere which holds gasses that freeze when Pluto is further away from the Sun, but when it is closer these gasses heat up.

First look at Pluto by the Hubble Space Telescope.

   Source: Hubblesite.org

Pluto and Charon are perhaps a product of an impact between Kuiper belt objects. Both at one time were thought to be close a double planet system.
 

Pluto has many interesting features with the dark and light patches in the south mainly consisting of large icy solids.

Pluto is at a distance of 5.9 billion kilometers and has a temperature of -229 °C.

Amazing features with alot of details can been seen from this image. The ice glaciers would perhaps flow similar to those on Earth.

Icy mountain ranges of Pluto stretch for hundreds of kilometers.

Pluto and Charon from final approach of New Horizon's.

Size of Pluto and Charon compared with Earth.

Pluto has a diameter of 2372 km according to recent measurements taken by the New Horizons spacecraft. When we compare this with Earth's 12,742 km, we get an idea of how tiny Pluto really is. Pluto maintains a surface gravity of just 0.063g, while Earth's is 1g.

A spectacular view of Pluto with the Sun's light creating  a halo.

Image of Pluto from New Horizon as it made its approach through the years.

Pluto comparison with other moons and Planets.

Simulation view of Nix

Nix is a satellite of Pluto which was discovered in 2005 by the Hubble Space Telescope. New Horizons measured Nix to be 32 Kilometers in diameter.

Simulation view of Kerberos with Pluto and Charon in view.

 Kerberos is another small moon which orbits Pluto.

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Until next time goodbye for now.

Interstellar Star Formation

A star is a dense cloud of gas that produces energy in its core by fusing lighter atoms into heavier ones. This high level of energy production causes the outer layers to shine as these layers are heated to thousands of degrees Celsius. Our nearest star the Sun produces and converts around 500 million tons of hydrogen and helium every second, with only 5 million that escapes from the core and reaches us as sun light.  A few days of energy from the Sun would be enough power for all of our needs for thousands of years. Of course the challenge lies in how to preserve and manage this solar energy?

What is is the interstellar medium? The interstellar medium is the space between stars and galaxies. This matter includes a collection of gas, dust and cosmic rays. It is a region of birth for stars.

By measuring a stars color we can determine its age. Blue stars are relatively short-lived compared to the redder stars. The blue stars die off over a period of a few hundred million years, but the redder stars continue to shine for billions of years. Therefore, as a star cluster ages, its color gradually shifts from blue to red.


Source: Hubblesite.org
Perhaps one of the most iconic images by Hubble, the above image of the Eagle Nebula shows large pillars of molecular gas and dust. In this region there are many young stars, the largest pillar in the image is about 3.86243exp13 kilometers or 24 trillion miles in size.



Source: Hubblesite.org 
The above image shows area of young star formation.
These clouds are held together by self-gravity and by the intense pressure that builds up in between the clouds. This in effect causes these molecular clouds to collapse into a center, which draws gas towards inside the cloud. When the density is high enough the clouds end up fragmenting and collapsing into itself. From these clouds of dust and gas are born stars and planets.

Source: Hubblesite.org  

The above is an area in our local Large Magellanic Cloud (LMC), where there is low-mass stars with giants beside it, known as LH 95 it is about 160,000 Ly away from Earth. The image was taken by Hubble's Advanced Camera for Surveys.

From these high detail Hubble images we are looking at regions of interstellar clouds. Self-gravity is a gravitational attracting among all parts of the same object. The sum of all these forces on every other particle is exerted towards the center. This gravity can be balanced by its own structural pressure similar to how Earth is made up from rocks, or by the outward force acting on the inward force creating a balance known as hydrostatic equilibrium. If either force is unstable the star can either expand outwards on inwards into itself. However in most clouds the internal pressure pushes outward more than inward.

From the above simulation we can get an idea of where the highlighted grey blob is the Large Magellanic Cloud (LMC)  and the milky way largely visible on the right.

Source: Hubblesite.org

The densest coolest interstellar clouds are called molecular clouds because they are mainly composed of hydrogen molecules. Once these molecular clouds begin to collapse the innermost becomes a star and outer parts can become planets. The innermost part of cloud is called a protostar. The surface of a protostar is thousands of times larger then the Sun and as a result is also more luminous.




Source: Hubblesite.org

LRLL 54361 a binary protostar, it demonstrates some unknowns about star formation. The protostar emits a burst of light at intervals perhaps caused by the eccentric orbit that it may exhibit.


Source: Hubblesite.org

The above is a spectacular image of blue newly formed stars in the Small Magellanic Cloud. The Small Magellanic Cloud is in the constellation of Tucana around 200,000 Ly away. This dwarf galaxy has far less stars than compared to our own galaxy.


Even though a protostar is so bright its often the case that we cannot even see it in visible light. One of the reasons is that this light is in the infrared spectrum. Also a protostar is often buried deep within molecular clouds thus making it identifiable a difficult process. The mass of a protostar determines if it will actually become a star, as it slowly collapses, the temperature in the center rises. A newly born star continues to readjust its structure until its energy that is being radiated is the same as energy being created inside of it, this hydrostatic equilibrium is crucial.

 Simulation of Milky Way being viewed from the Small Magellanic Cloud.

Simulation of close up a globular cluster of stars, NGC 6338.

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Until next time goodbye for now.

The Movement of Stars

For thousands of years ground based observers had speculated from their understanding that stars were immobile and that they were stationary relative to Earths perspective. This curiosity of mankind to ask such questions as, how far is that star? how big is it? and how bright is it?. These questions have brought great discoveries. Our nearest star Alpha Centauri also known as Rigil Kentaurus or Toliman is at a distance of 4.22 light-years. Rigil Kentaurus comes from the Arabic term meaning 'centaur's foot', this figure was visualized by Arab astronomers in the stars of this region.


With 1 Ly equal to 9.4605284 × 10¹² km, 4.22 Ly would make it a journey of 3.992342985 x 10¹³
km, making it a very long journey even with our current technology it would take over 100 years to reach our nearest star. Considering our galaxy the Milky Way is estimated to have around 400 Billion stars reaching our closest neighbor is still yet so far.


In 1718 research from English astronomer Edmond Halley proved the proper motion of star, he observed three bright stars Sirius, Arcturus and Aldebaran.
Proper motion is the angular change in position of a star across our line of sight on Earth. It is measured by astronomers and scientists by optical methods of photography several years apart and then measuring the movement of a star with respect to the stars in the distance or behind it over a period of time.



Sirius which is the brightest star in Earth's night sky with a magnitude of -1.46, is located in the constellation of Canis Major south of the celestial equator. It is perceived to be a single star but in fact is a binary star system consisting of Sirius A and Sirius B. Sirius is moving closer to our Solar System and will slowly increase in luminosity over the next 60,000 years.

[Simulation of orbit of Sirius A and Sirius B, Sirius A on right and Sirius B on left]

Arcturus is a star with a visual magnitude of -0.05 at a distance of 37 Ly. It is fourth brightest star of the northern hemisphere and is estimated to be about 25 times our Sun's diameter and 100 times as luminous.

[Simulation of Arcturus]

Aldebaran is a orange giant star about 65 Ly away. It marks the eye of Taurus the bull. It is about 150 times more luminous then the Sun. The name Aldebaran comes from the Arabic meaning 'the follower', it appears to follow the Pleiades cluster across the night sky.

[Aldebaran with the Pleiades cluster behind it]

Edmond Halley noticed that these three stars were more than 0.5 degrees away from previous positions given by the Greek astronomer Hipparchus who is famous for his discovery of the equinoxes in the second century BC. This shift of 0.5 degrees was apparent in the sky if observed over time. This is now called proper motion, which is defined as the change of position of a star on the celestial sphere. Proper motion is denoted by the Greek symbol Mu.


Despite being most famous first to calculate the orbit of a comet named after him Halley's comet. The discovery and study of proper motion is critical to understanding the celestial bodies of stars in our universe. It took 2000 years for this motion to change and become apparent to scientists. With this we can see that stars that have a large proper motion as with Barnard's star tend to be nearer to our position and stars that are further away have a much smaller proper motion.

Barnard's star is perhaps the best example of proper motion it travels 10.3 seconds of arc each year, an arc is a unit of angular measurement equal to one-sixtieth (¹⁄₆₀) of one degree

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Until next time goodbye for now.

The solar eclipse March 20th, 2015

[Picture of solar eclipse March 20th 2015 9:20am, Picture by Sidra Malik, Dundalk, Ireland ]

Millions of people around the world witnessed a spectacular phenomenon, the solar eclipse 2015. The Moon passed directly in front of the Moon to bring a solar eclipse to observers. Across United Kingdom, Ireland and eastern Europe experienced a partial eclipse. The Moon covered about 60 percent of the Sun.

[Simulation of solar eclipse viewed from space]

One of the most prominent features of the sky is the Moon. Over the thousands of years man has looked up at the night sky and has always seen he same side of the Moon. However the one thing that does change in appearance, is the sides that are illuminated so its appearance changes regularly throughout the day and seasons.

Whether it is today, tomorrow, next week or next year, the same side of the Moon and same patterns will still be observed. Many people make a false observation by thinking the Moon does not rotate however in fact the Moon does rotate on its axis. It rotates once for every revolution it makes around the earth and always keeping the same face towards the earth. This is quite an amazing phenomenon called synchronous rotation as the revolution and rotation are synchronized with perfection. The rotation is slightly elongated causing the near side always face towards the earth.

[Simulation of rotation of Moon around Earth]

The other side of the Moon which we seldom see in fact the far side or dark side of the Moon spends around the same amount of time in sunlight as the near side. This was unknown to man until recent advancement in space flight and technology.

[(simulation) Far side of moon receiving light from the Sun]

"Blessed is He Who made constellations in the skies (Space),
And placed therein a lamp (Sun)
And a Moon which has reflected light." - Al Quran

Unlike the Sun, the Moon does not have a source of light of its own, it reflects and shines by the light  received from the Sun.

There are three types of solar eclipse; total, partial and annular. A total solar eclipse occurs when the Moon completely blocks the disk of the Sun. This is one of the most amazing sights man can witness in nature.
A partial solar eclipse occurs when the Moon only partially covers the Sun.
An annular solar eclipse occurs when the Moon is slightly further away from the Earth in its orbit and appears smaller in sky, it goes over the sun but does not completely block it.

   [A total solar eclipse]

   [A partial solar eclipse]

   [An annular solar eclipse]

However you may be wondering despite all of this how is it that the Moon and the Sun seem to be the same size ?

This is due to a remarkable phenomenon by where the Sun and Moon appear to be the same size when we view from Earth. The Sun has a diameter which is about 400 times greater than the Moon but at the same time the Sun is also about 400 times farther away. The diameter of the Sun is 1,391,684 km, distance of Sun from Earth is 149,600,000 km. The diameter of the Moon is 3,476 km with a distance of 384,400 km.

A remarkable coincidence indeed!

One of the important astronomers of the years 858-929 was Al-Battani, Abu'Abudallah Muhammad ibn Jabir also know as Albateginus. An Arab astronomer who demonstrated that the Sun's distance from the Earth, its apparent angular size, varies which explained why both lunar and solar eclipses are made possible. He made the first truly accurate calculations of the solar year (365.24 days). 

[Crater on Moon named in honor of Albateginus]

He also produced a number of important trigonometric equations that are now commonly used across many disciplines of Engineering and other Sciences . Data produced by Albateginus continues to be used even today.


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To see a total solar eclipse you must be located at at a very narrow band where the Moon's shadow is cast onto the face of the Earth.
NASA's SDO (Solar Dynamics Observatory) which makes its path around earth in 24 hours is situated in a geosynchronous rotation around earth and is in unique situation where it views an eclipse where the Moon is covering the Sun and another eclipse where the Earth eclipses the Sun. 

We are not as lucky to see such eclipses simultaneously but the next eclipse to occur and be visible from Ireland will be in the year 2026 and hopefully it wont be cloudy day with such poor visibility as we had this time, so until next time goodbye!