Tag Archives: Astrophysics

A Brief History of the Universe

The universe is the biggest and oldest thing we know. It contains all existing matter and space. And its origin marks the beginning of time as far as we understand it. We don’t know what made the formation of the universe possible, nor why it occurred. The visible universe is currently about 93 billion light years wide.

A light-year is a distance that light travels in a year, which makes the universe about 880 trillion trillion metres wide. The visible universe is, however, still expanding, and we can measure that rate of expansion. Then, working backwards, we can figure out when the universe would have begun. To the best of our knowledge, the universe formed about 13.8 billion years ago in what is commonly referred to as the Big Bang.

This image shows the universe about 370000 years after the Big Bang, which is the oldest light that we’ve been able to record with the greatest precision. The image records ancient light or cosmic microwave background. The colours show tiny temperature fluctuations from an average temperature. These indicate areas of different densities, which became the stars and galaxies of today. Red spots are a bit hotter and blue spots a bit cooler. The image was recorded between 2009 and 2013, during the Planck mission, when the space observatory was operated by the European Space Agency, in conjunction with NASA, the National Aeronautics and Space Administration. Today, the universe is very cold. On average, it is 2.7Kelvin. Kelvin is a measure of temperature with the same magnitude as degrees Celsius. But 0 Kelvin equals minus 273.15 degrees Celsius.

In the universe, the hot parts, such as stars, make up only a tiny fraction. If we wind the clock backwards, the universe gets smaller. And this means the universe was hotter in the past. When matter gets hot, solids melt and liquids boil. The hot matter glows – red at first, but it becomes bluer as the temperature goes up. Eventually, all matter is gas. So we have a bright, glowing blob of gas. Going further back in time, as the gas gets hotter, the electrons are separated from the nuclei and a plasma is made. The temperature at this point is about 3000 to 6000 Kelvin and the glowing blob is white hot. As we go back further in time, the universe gets even smaller and hotter.

The nuclei themselves, containing protons and neutrons, are broken up. The reason for the breakup of nuclei is that the individual particles and the energy of the radiation are so great that the collisions of all this hot stuff are incredibly violent. The light is no longer in the visible spectrum. It is energetic enough to be x-rays and even gamma rays. Between just 10 seconds and 1000 seconds after the Big Bang, subatomic particles, including neutrons and protons, were formed. Neutrons live for just 9 minutes when they are free. Hence only those that stuck to protons during this period survived. All of the ordinary matter present today formed in this short window of time.

At about 1 microsecond after the Big Bang, the universe was very hot, at 10 to the 10 Kelvin, and quarks formed stable particles called hadrons. Before 1 picosecond, or 10 to the minus 12 seconds, the universe was an exotic place. The gas was hotter still and the laws of physics appeared different to how we see them today. The distinction between matter and radiation, such as light, cannot be detected. The forces of electromagnetism and the weak nuclear force also become indistinguishable. At the very earliest times, the universe was so hot and dense that we cannot yet describe them accurately.

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Venus and the Triply Ultraviolet Sun

Venus and the Triple Ultraviolet Sun
Image Credit: NASA/SDO & the AIA, EVE, and HMI teams; Digital Composition: Peter L. Dove (http://www.flickr.com/photos/pldove/)

Explanation: An unusual type of solar eclipse occurred in 2012. Usually, it is the Earth’s Moon that eclipses the Sun. That year, most unusually, the planet Venus took a turn. Like a solar eclipse by the Moon, the phase of Venus became a continually thinner crescent as Venus became increasingly better aligned with the Sun. Eventually, the alignment became perfect and the phase of Venus dropped to zero. The dark spot of Venus crossed our parent star. The situation could technically be labelled a Venusian annular eclipse with an extraordinarily large ring of fire. Pictured here during the occultation, the Sun was imaged in three colours of ultraviolet light by the Earth-orbiting Solar Dynamics Observatory, with the dark region toward the right corresponding to a coronal hole. Hours later, as Venus continued in its orbit, a slight crescent phase appeared again. The next Venusian transit across the Sun will occur in 2117. </center>

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Why Alien Life Would be our Doom – The Great Filter

New video by Kurzgesagt – In a Nutshell. Sharing this as it’s very interesting for all to know 🙂


The first 688 people to use this link will get 20% off their annual membership: http://brilliant.org/nutshell

Finding alien life on a distant planet would be amazing news – or would it? If we are not the only intelligent life in the universe, this probably means our days are numbered and doom is certain.

Kurzgesagt Newsletter: http://eepurl.com/cRUQxz

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The MUSIC of the video:

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Astronomy Picture of the Day – Global Aurora at Mars

See Explanation.  Clicking on the picture will download
 the highest resolution version available.Global Aurora at Mars 
Image Credit: MAVENLASP, University of ColoradoNASAExplanation: A strong solar event last month triggered intense global aurora at Mars. Before (left) and during (right) the solar storm, these projections show the sudden increase in ultraviolet emission from martian aurora, more than 25 times brighter than auroral emission previously detected by the orbiting MAVEN spacecraft. With a sunlit crescent toward the right, data from MAVEN’s ultraviolet imaging spectrograph is projected in purple hues on the right side of Mars globes simulated to match the observation dates and times. On Mars, solar storms can result in planet-wide aurora because, unlike Earth, the Red Planet isn’t protected by a strong global magnetic field that can funnel energetic charged particles toward the poles. For all those on the planet’s surface during the solar storm, dangerous radiation levels were double any previously measured by the Curiosity rover. MAVEN is studying whether Mars lost its atmosphere due to its lack of a global magnetic field.


Source: https://apod.nasa.gov/apod/ap171006.html


Quasar’s light yields clues to outflow

This artist’s impression shows the light of several distant quasars piercing the northern half of the Fermi Bubbles, an outflow of gas expelled by the supermassive black hole in the centre of the Milky Way. The NASA/ESA Hubble Space Telescope probed the quasars’ light for information on the speed of the gas and whether the gas is moving toward or away from Earth. Based on the material’s speed, the research team estimated that the bubbles formed from an energetic event between 6 million and 9 million years ago.

The inset diagram at bottom left shows the measurement of gas moving toward and away from Earth, indicating the material is traveling at a high velocity.

Hubble also observed light from quasars that passed outside the northern bubble. The box at upper right reveals that the gas in one such quasar’s light path is not moving toward or away from Earth. This gas is in the disc of the Milky Way and does not share the same characteristics as the material probed inside the bubble.



NASA, ESA, and Z. Levy (STScI)