by Madhurani Chavan | फेब्रुवारी 25, 2022 | English, मधुरानी
Betelgeuse is the ninth brightest star in the night sky and the second brightest in the constellation of Orion. It is also known by its official name or Bayer designation “alpha Orionis”. This is often shortened to alpha-Orionis or alpha ori. The star’s name is derived from the Arabic Yad al-Jauzā, which means “the hand of Orion”. It refers to the star’s position in the Orion constellation.
Classification
The star is classified as a red supergiant. It is one of the largest and most luminous observable stars. If Betelgeuse were in the solar system in place of the Sun, its surface would extend past the asteroid belt. It would possibly extend to the orbit of Jupiter and beyond. The resulting mass would be completely engulfing Mercury, Venus, Earth and Mars. Betelgeuse has a mass estimated to be around 30 times that of the Sun.
Variable brightness
It is one of the stars with greatly varying brightness. Sir John Herschel, in Outlines of Astronomy, first described the variation in Betelgeuse’s brightness in 1836. This makes it easy to spot and identify with the naked eye. It also has a distinctive reddish-orange color.
Eventual fate
Its fate depends on its mass. This is a critical factor that is not well understood. The most likely scenario is that the supergiant will continue to burn and fuse elements until its core is iron, at which point Betelgeuse will explode as a type II supernova. As of 2014, the most recent theory suggests that it will explode as a supernova within 1,00,000 years. The event is expected to leave a neutron star 20 km in diameter.
Compiled by: Madhurani Chavan
by Madhurani Chavan | फेब्रुवारी 25, 2022 | English, मधुरानी
Polaris is the brightest star in the constellation Ursa Minor and the 45th brightest star in the night sky. It is very close to the north celestial pole and is commonly used for navigation. Thus, it is also commonly known as the pole star, loadestar, or guiding star.
Star system of Polaris
It is actually a multiple-star system. It consists of one main star, Alpha Ursa Minoris (UMi) Aa and two smaller companions, Alpha UMi AB. There are also two distant components, Alpha UMi C and Alpha UMi D.
Classification and characteristics
Alpha UMi Aa is a yellow supergiant with a mass 4.5 times that of the Sun. The two smaller companions are as follows:
•Alpha UMi B – is a main-sequence star orbiting at a distance of 2400 AU and a mass 1.39 times that of the Sun.
• Alpha UMi Ab – is a very close main-sequence star at a distance of 18.8 AU and a mass 1.26 times that of the Sun.
Alpha UMi Aa is visible to the naked eye and even a modest telescope can see Alpha UMi B. The system is at an approximate distance of 434 light-years from Earth.
Pole star
Because Alpha UMi nearly lies in a direct line with the axis of Earth’s rotation “above” the North Pole, it stands almost motionless in the sky. As a result, all the stars of the Northern sky appear to rotate around Polaris. It makes an excellent fixed point to draw measurements for celestial navigation and astrometry.
The celestial North Pole is not fixed. It moves due to Earth’s motion. As a result, Polaris wants always a pole star and will not be one after a few centuries.
Compiled by: Madhurani Chavan
by Madhurani Chavan | फेब्रुवारी 25, 2022 | English, मधुरानी
Space begins where Earth’s atmosphere ends. There was a time when space was believed to be completely empty. However, this is not true. The vast gaps between the stars and the planets are filled with huge amounts of gases and dust. Even the emptiest parts of space contain at least a few hundred atoms or molecules per cubic meter.
• Space is black
There is neither air to breathe nor light to scatter in space, making it difficult for humans to survive. Space is black and not blue like a sky. This is because the number of oxygen molecules is comparatively less in space. It mainly consists of a vacuum and the molecules present are not sufficiently close because of which sound does not get transmitted.
• How big is it?
No one really knows how big space is. Long distances in space are measured in “light-year”, which represents the distance that light takes to travel in a year. This is roughly about 9.3 trillion km.
• Marvels of space
Besides vacuum, space consists of planets, stars, several hundred galaxies, matter, dust, gases and so on. Just like we have winds, there are solar winds that occur in space. Let us look at all the amazing things that exist high up in the heavens that leave us awestruck every time we explore them.
by Madhurani Chavan | फेब्रुवारी 25, 2022 | English, मधुरानी
Outer space is the empty void that exists between various celestial bodies, including Earth. Space is not completely empty. It consists of a hard vacuum with a low density of particles, mostly plasma of hydrogen and helium, as well as some electromagnetic radiation, magnetic fields, neutrinos, dust and cosmic rays.
Density and temperature
The baseline temperature in spaces is 2.7 Kelvin (K). We know this based on the background radiation from the Big Bang. There is a fourth state of matter called plasma, which is neither solid, liquid nor gaseous. Plasma accounts for most of the baryonic or ordinary matter in space. It has a density of less than one hydrogen atom per cubic meter and a temperature of millions of Kelvin. It lies in the space between the galaxies. The local concentrations of plasma have condensed into stars and galaxies.
Dark matter
Observations have provided evidence that 90% of the mass in most galaxies is in an unknown form called “dark matter”. Dark matter interacts with other matter through gravitational forces, but not electromagnetic forces. Current data indicates that the majority of the mass-energy in the observable universe is a poorly understood vacuum energy of space. Astronomers, over time, have labeled this as “dark energy”. Intergalactic space occupies the maximum volume of the universe.
Even space has laws
The Outer Space Treaty established the framework for international space law. This treaty was passed by the United Nations General Assembly in 1967. The treaty prevents any claims of national sovereignty and allows all the states to freely explore outer space. The 1979 Moon Treaty made the surfaces of objects like planets and the orbital space around these bodies, the jurisdiction of the international community covered by the Space Law.
Despite the drafting of the UN resolutions for the peaceful use of outer space, anti-satellite weapons have been tested in Earth’s orbit. Current legislation only prohibits weapons of mass destruction, like nuclear weaponry and atomic bombs being placed into outer space.
Space exploration
Humans began the physical exploration of space during the 20th century. The advent of high-altitude balloon flights followed by manned rocket launchers facilitated this exploration. Yuri Gagarin of the Soviet Union first achieved Earth’s Orbit in 1961. Unmanned spacecraft have reached all the known planets in the solar system since then. The high cost of getting into space means that manned spaceflights have been limited to the lower Earth orbit and the moon. Voyager 1 became the first human-made spacecraft to enter interstellar space, leaving the solar system in August 2012.
An expensive affair
The current economic burden prevents us from becoming a spacefaring civilization. Certain proposed concepts for doing this involve non-rocket space launchers such as rockoon, skyhook, a rocket sled and an air launch.
Other concepts include momentum exchange tethers that make use of centrifugal acceleration and ionic propulsion.
Space elevators are also one of the proposed means of conducting space travel without the use of expensive resources. A space elevator extends into the space attached to the surface of Earth with the help of a ribbon-like structure.
These proposed concepts look promising when it comes to reducing the financial implications of space travel and exploration as they aim at saving on fuel, energy and loss of equipment and human lives.
Ccompiled by: Madhurani Chavan
by Madhurani Chavan | फेब्रुवारी 25, 2022 | English, खगोलशास्त्र, मधुरानी
Outer space is a void that lies beyond the uppermost ranges of the atmosphere of Earth and between all other objects in the universe. Although it is considered to be a void, outer space can be thought of as an environment in itself. Radiation and objects pass freely through it. A human or another living being in the outer space environment without any protection would not survive even for a few moments.
Total vacuum
The basic environmental characteristic of outer space is the vacuum for the nearly total absence of gas molecules. The gravitational attraction of large bodies, such as planets and stars, pulls the gas molecules close to their surfaces, which leaves the space between them practically empty. Stray gas molecules are usually found between these bodies. Their density is so low that they can be thought of as being unreal.
Effect of pressure in outer space
On Earth, the atmosphere applies pressure in all directions. At sea level, it is 101 kilopascals but in space, it is almost zero. With no external pressure, the air within a human’s lungs, without any kind of protective shield, would immediately rush out into the vacuum.
Effect of pressure in space on humans
The sudden absence of external pressure that balances the internal pressure of the body would damage delicate tissues such as the eardrums and the capillaries. The body would swell, causing tissue damage and a lack of oxygen supply to the brain. This would result in unconsciousness in under 10 seconds. Dissolved gases in the body fluids would expand, causing the skin to stretch much like a pumped balloon. Bubbles would form in the bloodstream making it ineffective as transport of oxygen and nutrients to the body’s cells.
Temperature in space
The temperature in outer space is hazardous. The objects that receive sunlight in space and are at Earth’s distance from the Sun, can scale to over 120 °C while those on the shaded side can be as low as – 100 °C. Because of the space environment, a comfortable temperature range cannot be sustained, posing grave problems.
Other environmental factors
There are other environmental factors in space such as microgravity, radiation of the electrically charged particles from the Sun, ultraviolet radiation and meteoroids. Meteoroids are small bits of rock and metal leftover from the formation of the solar system about trillions of years ago and from comets and asteroids collisions. They are small but travel at very high velocities and can easily seep into the human skin. Debris from previous space missions is also very dangerous. A tiny paint chip traveling at thousands of kilometers per hour can do significant damage.
Compiled by Madhurani Chavan
