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Happy leap day!!!

Leap Day…Why Does It Exist?

Once every four years, an extra calendar day is added: a leap day. But why?

The reason for adding leap days to the calendar is to align the calendar year with the actual year – which is defined by the time it takes Earth to circle the sun. It is equal to 365 days, 5 hours, 48 minutes and 46 seconds, or 365.24219 days.

If all calendar years contained exactly 365 days, they would drift from the actual year by about 1 day every 4 years. Eventually, July would occur during the northern hemisphere winter! Wouldn’t that be weird?

To correct (approximately), we add 1 day every 4 years…resulting in a leap year.

By making most years 365 days but every fourth year 366 days, the calendar year and the actual year remain more nearly in step.

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Celestial Wonders- Binary Stars (#1)

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 as seen from the Earth when viewed through  an optical telescope, 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  

Why study Binary stars ?

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.

Also,it is estimated that 75% of the stars in the Milky Way galaxy are not single stars, like the Sun, but multiple star systems, binaries or triplets.

The Brightest star in the sky is a binary.

This is true. Sirius (aka the Dog star)  - the brightest star in the sky is actually a binary star system.

When it was discovered in 1844 by the German astronomer Bessel, the system was classed as an astro-metric 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 ?

Hell Yeah! 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.

A binary Black Hole system ?

Definitely! A binary black hole (BBH) is a system consisting of two black holes in close orbit around each other.

In fact the LIGO experiment which confirmed the existence of Gravitational waves was able to acquire its data when two Binary Black Holes Collided and merged into one. This phenomenon sent ripples in the fabric of space-time which we call as a Gravitational Wave.

The Universe is amazing huh?

If you found this interesting, check out:

A Denied stardom status - Jupiter

Black Holes are not so Black (Part 3) - Gravitational Waves

Tiggghhhttt

Neil knows what's up

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