Tag Archives: Discovered

Discovered : A Belt of Antimatter Surrounding Earth

Anti-particles are not as exotic as many think and here’s further proof. The PAMELA spacecraft has detected a ring of anti-protons around the Earth, confined in that region by Earth’s magnetic field. These may be confined in that small region for hours before annihilating with matter and producing radiation.

This ground-breaking discovery was reported by PAMELA spacecraft recently. PAMELA, acronym for Payload for Anti-Matter Exploration and Light-nuclei Astrophysics, is a satellite that was launched to further cosmic ray astrophysics on 15th June 2006. It was specifically built to focus on the occurrence and interactions of positrons (anti-electrons) and anti-protons in the space around Earth.

The PAMELA spacecraft

Some theoretical considerations

Anti-matter is a theoretical necessity, which can be deduced from the symmetry of theories in physics. It was first predicted by the great Paul Dirac in 1931, following the interpretation of results given by his own equation (unsurprisingly called, the Dirac Equation) to describe the electron. His wild prediction of the positron was soon experimentally verified the following year by Carl Anderson, who detected it in his lab. (Remember, that the neutron was not yet known. It was also discovered in 1932 late in the year.) The scientific impact and importance can be gauged from the fact that Anderson went onto win the Nobel Prize in 1936, just four years after the discovery. Now, we know that every particle must have its anti-particle.

When particles and anti-particles collide, they annihilate producing (two) gamma rays. As always in physics, the reverse can also happen. Given certain conditions, a gamma ray can give rise to two particles a particle and an anti-particle obeying Einstein’s famous equation E=mc2. (Due to other strong constraints imposed by symmetries of physics, two particles or two anti-particles cannot be produced.)

The Van Allen Radiation Belts (Courtesy: Addison Wesley Longman)

In our atmosphere too, the same phenomenon happens. High energy cosmic rays bombard the Earth’s atmosphere producing matter and anti-matter particles. These can be kept separated out from each other due to the presence of Earth’s magnetic field, since moving particles of opposite charge behave very differently in magnetic fields. Furthermore, magnetic fields can confine these particles in pockets. They can remain stable for hours on average, before encountering matter particles and annihilating. Theoreticians have long predicted the presence of anti-protons in the Van Allen Belts (belts of charged particles surrounding Earth), in addition to positrons, because of the high energy of the bombarding cosmic rays. Anti-protons are much more massive than anti-electrons and thus require more energy to be produced. Most radiation can produce electron-positron pairs, but do not have enough energy to produce proton-antiproton pairs.

Enter PAMELA

PAMELA collected data over 850 days from the South Atlantic anomaly (a region over the South Atlantic ocean, where the Van Allen belts come closest to the Earth’s surface) and confirmed this theoretical prediction.

As this news spreads, there will be inevitable attempts at grabbing eyeballs by projecting this as the new cheap, easily available energy source. You can lend an ear to that at your own risk.

Discovered: A Super Massive Black Hole Weighing As Much As Two Billion Suns

This is a big astrophysical find, literally big! The Chandra X-Ray telescope has detected the signature of a supermassive black hole by observing the hot gases falling into it. The estimated mass of the black hole is a huge 2 Billion times the mass of the Sun!

The compact object lies at the heart of the galaxy known as NGC 3115, located at a distance of 32 million light-years away from Earth, making this the closest billion-solar-mass object to Earth. Astronomers have long been interested in the activity in this region, especially the gas falling into the central object. There have been various observations in the various frequencies, but this is only the first time when the X-Ray signatures have been clearly observed. The Chandra data suggests a huge mass for the black hole, given the temperature of the glowing gas falling into it. Only if the gas glows extremely intensely, does it give off X-Rays. NGC 3115 is about a million times brighter in X-Rays than in visible light.

How They Found Out the Mass

There is a term, called Bondi radius, named after the astrophysicist Hermann Bondi, which describes how the gas is affected by the black hole gravity. It is defined as the distance at which the gravity first starts dominating the random kinetic motion of the gas and the gas starts spiraling into the black hole.

The NGC 3115 galaxy

The data from the Chandra telescope suggests that the Bondi Radius is 700 light years away from the black hole!! In comparison, the closest star to Earth, after the Sun, is about 4 light years away. This gives an estimate of the mass of the black hole and the calculation suggests 2 billion solar masses!!

Any Use?

This finding is not only one for public consumption, but also scientific fodder. It may help to explain how matter flows into a black hole, as a tremendous amount of data is available due to the luminosity of the black hole.

It also brings up questions. Scientists still don’t know how such extremely massive black holes stay dim. As Dr. Jimmy Irwin, assistant professor of University of Alabama’s Physics Department says:

A leading mystery in astrophysics is how the area around massive black holes can stay so dim, when there’s so much fuel available to light up.

It is often said that astronomy is a humbling science. This just confirms that saying.

Discovered: A Small Asteroid Which Shares Orbit With Earth

A tiny asteroid, having roughly the same orbit as the Earth, has been discovered. The companion asteroid is about 300 yards across. It leads the Earth as both the objects orbit the Sun. However, the asteroid has variable speed and a more eccentric orbit, often leading the Earth by as much as half-an-orbit.

The finding is due to work by Martin Connors of Canada’s Athabasca University and his colleagues. The findings have been published in the journal Nature.

The new object

The asteroid has been named 2010 TK7, and was discovered last year by NASA’s WISE satellite. This is the first time such a companion rocky body has been discovered to share the orbit with Earth. Many such bodies are known to either share the orbit with Jupiter or Saturn or become their moons. In fact, the fate of many objects sharing orbits with such large planets is that they eventually become satellites.

Asteroids are giant rocks in space, orbiting the Sun, believed to be remnants of the planet forming era. These are leftovers, those chunks which did not form planets. Among the big asteroids in the Solar System is Ceres, which has its own orbit between Mars and Jupiter. It is believed to be remnants of a planet which broke up, probably after being struck by a large comet.

Earth is not alone

Rocky bodies which share an orbit with a planet are called Trojans’. This object 2010 TK7 is the first Trojan found for Earth. Jupiter is known to have about 5000 Trojans, rocks brought to it by its intense gravitational pull. Mars, Neptune and Saturn also have their share, though the number is much less than that of Jupiter.

Trojans around Jupiter (green dots)

There is no fear of an asteroid crashing onto the Earth in the immediate future. It’s just a harmless body accompanying the Earth on its annual journey around the Sun.

Hubble Discovers a Fourth New Moon of Pluto

Hubble has done it again. It has captured a hitherto unknown fourth moon of Pluto, the dwarf planet. The three known moons of Pluto are Charon, Nix and Hydra. The fourth one, discovered just recently on 3rd July, 2011, and officially announced today by NASA and SETI, is temporarily known as P4.

Pluto was stripped of its planet tag on 24th August, 2006 and was relegated to the status of dwarf planet’ along with Eris and Ceres. Eris is, in fact, more massive than Pluto.

An animation showing Pluto. Done using images from Hubble (Photo: NASA)

Charon is the most well-known moon of Pluto and was the only moon discovered till 2005. It is quite large, with a size comparable with Pluto. In 2005, two newer moons were discovered and named Nix and Hydra. It is not known whether this recently discovered moon, P4, was there at the time of the discovery of the previous moons or was captured more recently.

The photo captured by Hubble. (Courtesy: SETI/NASA)

It was due to the wonder called the Hubble Space Telescope that a cold object, tiny in size and moving fast around a very distant body could be photographed. Mark Showalter of SETI Institute in Mountain View, California has this to say:

I find it remarkable that Hubble’s cameras enabled us to see such a tiny object so clearly from a distance of more than 3 billion miles (5 billion km).

The diameter of the new moon is just 8-21 miles, while Charon, by comparison, is a giant at 648 miles. Nix and Hydra are both about 50 miles in diameter.

NASA aims to discover more about the body least known to man with the upcoming New Horizons mission. New Horizons will hope to fly past Pluto in 2015, using inputs from Hubble’s photos to chart out its path.