Today in History

Comet Hale-Bopp (formally designated C/1995 O1) was probably the most widely observed comet of the twentieth century, and one of the brightest seen for many decades. It was visible to the naked eye for a record 18 months, twice as long as the previous record holder, the Great Comet of 1811.
Hale-Bopp was discovered on 23 July 1995 at a very large distance from the Sun, raising expectations that the comet could become very bright when it passed close to the Sun. Although comet brightnesses are very difficult to predict with any degree of accuracy, Hale-Bopp met or exceeded most predictions for its brightness when it passed perihelion on April 1 1997. The comet was dubbed the Great Comet of 1997.
The passage of Hale-Bopp was notable also for inciting a degree of panic about comets not seen for decades. Rumours that the comet was being followed by an alien spacecraft gained remarkable currency, and inspired a mass suicide among followers of a cult named Heaven's Gate.

Discovery
The comet was discovered by two independent observers, Alan Hale and Thomas Bopp, both in the United States. Hale had spent many hundreds of hours searching for comets without finding one, and was tracking known comets from his driveway in New Mexico when he chanced upon Hale-Bopp, with an apparent magnitude of 10.5, near the globular cluster M70, in the constellation of Sagittarius, just after midnight. Hale first established that there was no other deep-sky object near M70, and then consulted a directory of known comets, finding that no known objects were in this area of the sky. Once he had established that the object was moving relative to the background stars, he emailed the Central Bureau for Astronomical Telegrams, the clearing house for astronomical discoveries.
Bopp did not own a telescope. He was out with friends near Stanfield, Arizona observing star clusters and galaxies when he chanced across the comet(Mikkel) while at the eyepiece of his friend's telescope. He realised he might have spotted something new when he checked his star atlases to find out what other deep-sky objects were near M70, and found that there were none. He contacted the Central Bureau of Astronomical Telegrams via telegram. The following morning, it was confirmed that this was a new comet, and it was named Comet Hale-Bopp, with the designation C/1995 O1. The discovery was announced in International Astronomical Union circular 6187.

Is anyone looking for extraterrestrial life?

Despite the fact that alien life forms have never been discovered, the search for extraterrestrial intelligence (or SETI, as it is called) remains a popular pursuit. Astronomers (scientists specializing in the study of matter in outer space) believe that if life does exist on other planets, we now possess the technological capability of finding it and perhaps even communicating with it.
Most modern SETI missions use radio telescopes—instruments consisting of a large concave dish with an antenna at the center, tuned to a certain wavelength, that receive and process radio waves. The radio telescopes, tuned to nearby stars, listen for signals that may have been sent by alien civilizations.
The first large-scale SETI experiment, called Project Ozma, was begun by astronomer Frank Drake (1930-) in 1960. Drake conducted Project Ozma at the National Radio Astronomy Observatory at Green Bank, West Virginia. The object of the experiment was to search for signs of life in distant solar systems through intergalactic radio waves.

Unidentified flying object (UFO) expert J. Allen Hynek (1910-1986) developed the following scale to describe encounters with extraterrestrial beings or vessels:
Close Encounter of the First Kind— sighting of a UFO at close range with no other physical evidence.
Close Encounter of the Second Kind—sighting of a UFO at close range, but with some kind of proof, such as a photograph, or an artifact from a UFO.
Close Encounter of the Third Kind— sighting of an actual extraterrestrial being.
Close Encounter of the Fourth Kind— abduction by an extraterrestrial spacecraft.

Who invented the telescope?

Hans Lippershey (ca. 1570-1619), a German-Dutch lens grinder and spectacle (glasses) maker, is generally credited with inventing the telescope. This is because in 1608 Lippsershey became the first scientist to apply for a patent for the telescope. (A patent is a grant made by a government that allows the creator of invention the sole right to make, use, and sell that invention for a set period of time.) Two other inventors, Zacharias Janssen and Jacob Metius, also developed telescopes around this time. Modern historians consider both Lippershey and Janssen to be likely candidates for the title of "inventor of the telescope," with Lippershey possessing the strongest claim.

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.