Parts of a day!

whatdidulearntoday:

I was under the impression that there were only 4 parts to day- morning, afternoon, evening and night. It blew my mind when i found out that technically there are ten parts to it!.

1.Dawn

The first appearance of light ( very weak light ) in the sky.

image

2.Twilight

It is the time between Dawn and Sunrise.

image

3.Sunrise

The instant at which the upper edge of the Sun appears over the eastern horizon in the morning.

image

4.Morning.

Morning is the period of time between dawn and noon ( 12 ‘o’ clock in the daytime).

image

5.Daylight.

Constitutes all the time that the sun is right above our heads.

image

6.Evening.

The period of the day between late afternoon and night.

image

7.Sunset

The time of sunset is defined in astronomy as the moment when the trailing edge of the Sun’s disk disappears below the horizon.

image

8. Twilight

The time between Sunset and Dusk.

image

9.Dusk.

Dusk is the darkest stage of twilight in the evening.

image

10.Night.

The complete absence of direct sunlight. (Since moon light is a form of indirect sunlight )

image
Advertisements

astronomicalwonders:

The Fairy of The Eagle Nebula – M16

“The dust sculptures of the Eagle Nebula are evaporating. As powerful starlight whittles away these cool cosmic mountains, the statuesque pillars that remain might be imagined asmythical beasts. Pictured above is one of several striking dust pillars of the Eagle Nebula that might be described as a gigantic alien fairy. This fairy, however, is ten light years tall and spews radiation much hotter than common fire. The greater Eagle Nebula, M16, is actually a giant evaporating shell of gas and dust inside of which is a growing cavity filled with a spectacular stellar nursery currently forming an open cluster of stars. The above image in scientifically re-assigned colors was released in 2005 as part of the fifteenth anniversary celebration of the launch of the Hubble Space Telescope.”

Credit: NASA/Hubble/APOD

The Week at FYP!

The horse head nebula.

1. Baffling Polymer Balls behavior.

2. Bullet leaving barrel at 1 million frames per second.

3. Milky Way Time Lapse.

4. Stephen Hawking’s words of wisdom.

5. Celestial Wonders- Binary stars.

6. ISS is the third brightest object in the night sky.

7. Liquid Oxygen is magnetic.

ISS is the third brightest object in the night sky!

It often comes as a surprise to people when i tell them that the space station can be seen with the naked eye! Flying at 400 km above your head, the ISS looks like a really fast moving airplane in the sky.

The ISS isn’t brighter than the day sky and hence cannot be seen during the day. But in the night, it’s the third brightest object in the sky! It reflects the sunlight off the solar panels on its surface.

Spot the station!

If you would like to see the ISS for yourself, NASA ‘s Spot the station! is at your disposal. Register with your email address/mobile number and every time the ISS passes by your town/city, you will get a notification with the time, duration and inclination.

image

Have fun!

(Extras: There are mobile phone apps which you could use too, like the ISS detector satellite detector for android. At the end of the day all that matters is what is convenient to you.

ISS tracker– Real time tracking of the ISS)

Celestial Wonders- Binary Stars.

image

The twins of the stellar world are binary star systems.A binary star is a star system consisting of two stars orbiting around their common center of mass.When two stars appear close together in the sky, the situation is known as an “optical double”. This means that although the stars are aligned along the same line of sight, they may be at completely different distances from us. This occurs in constellations; however, two stars in the same constellation can also be part of a binary system.

image

Artist’s impression of the sight from a (hypothetical) moon of planet HD 188753 Ab (upper left), which orbits a triple star system( yes, a Triple Star system!). The brightest companion is just below the horizon.

image

Binary star systems are very important in astrophysics because calculations of their orbits allow the masses of their component stars to be directly determined, which in turn allows other stellar parameters, such as radius and density, to be indirectly estimated. This also determines an empirical mass-luminosity relationship (MLR) from which the masses of single stars can be estimated.

It is estimated that approximately 1/3 of the star systems in the Milky Way are binary or multiple, with the remaining 2/3 consisting of single stars.

The Brightest star in the sky is a binary.

image

This is true. When it was discovered in 1844 by the German astronomer Bessel, the system was classed as an astrometric binary, because the companion star, Sirius B, was too faint to be seen. Bessel, who was also a mathematician, determined by calculations that Sirius B existed after observing that the proper of Sirius A (the main star) followed a wavy path in the sky, rather than a uniform path. Sirius can now be studied as a visual binary because, with improving technology and therefore improved telescopes, Sirius B was able to be seen, although not for 20 years after Bessel had correctly predicted its existence.

Black Holes in a binary System ?

image

The term “binary system” is not used exclusively for star systems, but also for planets, asteroids, and galaxies which rotate around a common center of gravity. However, this is not a trick question; even in star binaries, the companion can be a black hole. An example of this is Cygnus X-1.

The universe is pretty amazing huh?…

Why did the Earth start spinning?

Our Solar System formed about 4.6 billion years ago when a huge cloud of gas and dust started to collapse under its own gravity. 

As the cloud collapsed, it started to spin. Some of the material within this cloud gathered into swirling eddies and eventually formed into planets. As the planets formed, they kept this spinning motion. This is similar to what you see when skaters pull in their arms and spin faster. As material gathered in more closely to form a planet, like Earth, the material spun faster. 

Why does the Earth still Spin?

To put it bluntly, the earth is still spinning because there are no forces acting to make it stop spinning! This is known as Inertia – an inherent law of nature.

Inertia is the tendency of an object to remain in motion unless and until acted upon by an unbalanced force.

( Source : http://coolcosmos.ipac.caltech.edu/ask/59-Why-does-Earth-spin-)