Georges Lemaître

Scientific research shows that the universe has been expanding at an accelerating rate; this is said to be due to the dark energy that makes up some 70 percent of the total energy density of today's universe. This discovery further bears out the big bang theory, which had been first proposed by astrophysicist and cosmologist Georges Lemaître in 1927. LeMaître, who was born on this date in 1894, stated that the universe began some 20 billion years ago with the violent explosion of a small mass of matter at extremely high density and temperature.

Georges Henri Joseph Éduard Lemaître (July 17, 1894 – June 20, 1966) was a Belgian Roman Catholic priest, honorary prelate, professor of physics and astronomer at the Université catholique de Louvain.
Lemaître proposed what became known as the Big Bang theory of the origin of the Universe, which he called his 'hypothesis of the primeval atom'.

After studying humanities at a Jesuit school (Collège du Sacré-Coeur, Charleroi), Lemaître entered the civil engineering school of the Catholic University of Leuven at the age of seventeen. In 1914, at the beginning of World War I, he paused his studies to engage as a volunteer in the Belgian army. At the end of hostilities, he received the Military Cross with palms.
After the war, he undertook studies in physics and mathematics and began to prepare for priesthood. He obtained his doctorate in 1920 with a thesis entitled l'Approximation des fonctions de plusieurs variables réelles (Approximation of functions of several real variables), written under the direction of Charles de la Vallée-Poussin. He was ordained a priest in 1923.
In 1923, he became a graduate student in astronomy at the University of Cambridge, spending one year at St Edmund's House (now St Edmund's College, Cambridge). He worked with the astronomer Arthur Eddington who initiated him into modern cosmology, stellar astronomy and numerical analysis. He spent the following year at Harvard College Observatory in Cambridge, Massachusetts with Harlow Shapley, who had just gained a name for his work on nebulae, and at the Massachusetts Institute of Technology, where he registered for the doctorate in sciences.

On March 17, 1934, Lemaître received the Francqui Prize, the highest Belgian scientific distinction, from King Léopold III. His proposers were Albert Einstein, Charles de la Vallée-Poussin and Alexandre de Hemptinne. The members of the international jury were Eddington, Langevin and Théophile de Donder. Another distinction that the Belgian government reserves for exceptional scientists was allotted to him in 1950: the decennial prize for applied sciences for the period 1933-1942.

In 1936, he was elected member of the Pontifical Academy of Sciences.
In 1941, he was elected member of the Royal Academy of Sciences and Arts of Belgium.
In 1946, he published his book on L'Hypothèse de l'Atome Primitif (The Primeval Atom Hypothesis), a book which would be translated into Spanish in the same year and into English in 1950.
In 1953 he was given the very first Eddington Medal award of the Royal Astronomical Society.
During the 1950s, he gradually gave up part of his teaching workload, ending it completely with his éméritat in 1964.
At the end of his life, he was devoted more and more to numerical calculation. He was in fact a remarkable algebraicist and arithmetical calculator. Since 1930, he used the most powerful calculating machines of the time like the Mercedes. In 1958, he introduced at the University a Burroughs E 101, the University's first electronic computer. Lemaître kept a strong interest in the development of computers and, even more, in the problems of language and programming. With age, this interest grew until it absorbed him almost completely.
He died on June 20, 1966 shortly after having learned of the discovery of cosmic microwave background radiation, proof of his intuitions about the birth of the Universe.

Three Great Space Telescopes

The Spitzer Space Telescope (formerly the Space Infrared Telescope Facility or SIRTF) The name chosen was that of Dr. Lyman Spitzer, Jr., the first to propose placing telescopes in space, in the mid-1940s. The US$ 800 million Spitzer was launched on Monday 25 August 2003 at 1:35:39 (EDT) from Cape Canaveral Air Force Station, Florida.
Launch vehicle: Delta II 7920H ELV
Mission length: 2.5-5+ years
Mass: 950 kg (2090 lb)
Orbit Location: the Sun
Orbit period: 1 year
Diameter: 0.8 m
Focal Lenght: 10.2 m



The Chandra X-ray Observatory is a satellite launched on STS-93 by NASA on July 23, 1999. It was named in honor of Indian-American physicist Subrahmanyan Chandrasekhar who is known for determining the mass limit for white dwarf stars to become neutron stars. "Chandra" also means "moon" or "luminous" in Sanskrit.
Launch vehicle: Space Shuttle Columbia STS-93
Mission length: 4 days, 22 hours, 50 minutes, 18 seconds
Mass: 4,790 kg (10,600 lb)
Orbit period: 64.2 hours
Diameter: 1.2 m (3.9 ft)
Focal Lenght: 10 m (33 ft)


The Hubble Space Telescope (HST; also known colloquially as "the Hubble" or just "Hubble") is a space telescope that was carried into orbit by a Space Shuttle in April 24 1990. It was named in honor of the American astronomer, Edwin Hubble. Although not the first space telescope, the Hubble is one of the largest and most versatile, and is well known as both a vital research tool and a public relations boon for astronomy. The HST is a collaboration between NASA and the European Space Agency, and is one of NASA's Great Observatories, along with the Compton Gamma Ray Observatory, the Chandra X-ray Observatory, and the Spitzer Space Telescope
Mass: 11,110 kg (24,250 lb)
Orbit period: 96–97 minnutes
Diameter: 2.4 m
Focal Lenght: 57.6 m
Orbit location: low Earth orbit

Hubble Deep Field

Hubble Ultra Deep Field is the most important image ever taken by humanity.

In late September 2003 Hubble Space Telescope took this picture about 47 billion light years away.

In this NASA handout, a view of deepest view of the visible universe ever achieved are seen in a Hubble Telescope composite photograph released March 9, 2004. The Hubble Ultra Deep Field (HUDF) photograph is a composite of a million one-second exposures and reveals galaxies from the time shortly after the big bang.

Dark Energy, Dark Matter

What is dark energy? More is unknown than is known — we know how much there is, and we know some of its properties; other than that, dark energy is a mystery — but an important one. Roughly 70% of the Universe is made of dark energy. Dark matter makes up about 25%. The rest - everything on Earth, everything ever observed with all of our instruments, all normal matter adds up to less than 5% of the Universe. Then again, maybe it shouldn't be called "normal" matter since it is a small fraction of the Universe!

Ocean and Earth System

Just by looking at images of Earth from space, it's clear that the ocean is a significant piece of the Earth's story. In fact, the ocean represents over 70% of the Earth's surface and contains 97% of all water on Earth. The ocean stores heat like a "fly wheel" for climate. Its huge capacity as a heat and water reservoir moderates the climate of Earth. Within this Earth system, both the physical and biological processes of the ocean play a key role in the water cycle, the carbon cycle, and climate variability.

Even if you live nowhere near the ocean, you will still experience the ocean's influence in our Earth system. Most of the rain that falls on landcomes from the tropical ocean. The ocean is the primary driver of weather and climate and can give us clues to global phenomenon such as El Niño. The phytoplankton (microscopic plants) that live in the ocean are responsible for almost half the oxygen you inhale and play a vital role in the carbon cycle. Far inland from the ocean, fields of crops enjoy rainwater that traveled through the water cycle and spent a few days or perhaps thousands of years cycling through the ocean.

Parallax

Try this: your "point of view" makes a difference!Hold up your thumb at arm's length. With one eye closed, line up your thumb with an object in the distance. Now switch eyes so that only the other eye is open. Does your thumb suddenly change position? Move your thumb closer to your nose and try again. Can you see your thumb jump even more?
Astronomers call this effect "parallax." The closer an object, the more it appears to shift against the distant background, when viewed from two different spots.

The Moon

Did you ever notice that the Moon always looks the same? Sure, it waxes and wanes from a new moon to a full moon, but the bright and dark patches on the Moon always look the same. In fact, these features are so familiar that people call it the Man in the Moon.
This is because the Moon always points the same face towards the Earth. The Moon does actually rotate on its axis, it's just that the amount of time it takes to make a complete orbit around the Earth matches the amount of time it takes to complete one rotation. In both cases, this is 27.3 days.
So, when you hear people refer to the far side of the Moon, they're talking about the part of the Moon that always faces away from the Earth. Until we sent spacecraft into orbit around the Moon to take pictures, nobody on Earth had ever seen what the far side of the Moon looks like.
But why does this happen? Over the few billions years since its formation, the Moon has become tidally locked with the Earth. In the distant past, the Moon had different rotation and orbital speeds, and it showed all of its sides to our planet. But the gravity of the Earth tugged at the irregular shapes on the Moon, causing it to slow its rotation down until it was exactly the same length as its orbit.
The Earth, on the other hand, has so much mass that the force of gravity from the Moon pulling on Earth can't overcome its rotational speed. The Moon does create the tides, though, and causes the ground to rise and fall - it's just such a small amount that you can't feel it.
Sometimes people mistakenly call this the dark side of the Moon. But there is no dark side of the Moon. Think about it, when we're seeing a new moon, that's because the familiar part that we can always see is in shadow. But at that point, the far side will be bathed in sunlight.

How Does the Earth Protect Us From Space?

Answer: Our Earth keeps us very safe from a dangerous Universe that's always trying to kill us in new and interesting ways.
Risk: Cosmic rays are high energy particles fired at nearly the speed of light by the Sun, supermassive black holes and supernovae. They have the ability to blast right through your body, damaging DNA as they go. Long term exposure to cosmic rays increases your chances of getting cancer. Fortunately, we have our atmosphere to protect us. As cosmic rays crash into the atmosphere, they collide with the oxygen and nitrogen molecules in the air.
Risk: Gamma rays and X-rays. As you know, radiation can damage the body. Just a single high-energy photon of gamma rays can cause significant damage to a living cell. Once again, though, the Earth's atmosphere is there to protect us. The molecules in the atmosphere absorb the high-energy photons preventing any from reaching us on the ground. In fact, X-ray and gamma ray observatories need to be built in space because there's no way we can see them from the ground.
Risk: Ultraviolet radiation. The Sun is bathing the Earth in ultraviolet radiation; that's why you get a sunburn. But the ozone layer is a special region of the atmosphere that absorbs much of this radiation. Without the ozone layer we would be much more exposed here on the surface of the Earth to UV rays, leading to eye damage and greater incidence of skin cancer.
Risk: Solar flares. Violent explosions on the surface of the Sun release a huge amount of energy as flares. In addition to a blast of radiation, it often sends out a burst of plasma traveling at nearly the speed of light. The Earth's magnetosphere protects us here on Earth from the effects of the plasma, keeping it safely way from the surface of the planet. And our atmosphere keeps the X-ray/gamma ray radiation out.
Risk: Cold temperatures. Space itself is just a few degrees above absolute zero, but our atmosphere acts like a blanket, keeping warm temperatures in. Without the atmosphere, we'd freeze almost instantly.
Risk: Vacuum. Space is airless. Without the Earth, there'd be no air to breath, and the lack of pressure damages cells and lets water evaporate out into space. Vacuum would be very, very bad.

Q & A

Q: What element is most plentiful on the Sun?
A: Hydrogen. The Sun is made up of about 75% hydrogen and 25% helium. About 0.1% is metals (made from hydrogen via nuclear fusion). This ratio is changing over time (very slowly), as the nuclear reactions continue, converting smaller atoms into more massive ones.

Q & A

Q: Why can't we see gravity?
A: First of all, we can only see the light that is reflected from things (we don't see the thing itself), and gravity doesn't reflect light. Gravitational lensing, however, is the displacement of light due to the warping of space by a gravitational lens (a massive object in space that bends light that passes by it, due to the gravitational forces). This is a way that gravity can be "seen."