A Mercury Transit Sequence
(via APOD; Image Credit & Copyright: Dominique Dierick )
This coming Monday, Mercury will cross the face of the Sun, as seen from Earth. Called a transit, the last time this happened was in 2006. Because the plane of Mercury’s orbit is not exactly coincident with the plane of Earth’s orbit, Mercury usually appears to pass over or under the Sun. The above time-lapse sequence, superimposed on a single frame, was taken from a balcony in Belgium shows the entire transit of 2003 May 7. The solar crossing lasted over five hours, so that the above 23 images were taken roughly 15 minutes apart. The north pole of the Sun, the Earth’s orbit, and Mercury’s orbit, although all different, all occur in directions slightly above the left of the image. Near the center and on the far right, sunspots are visible. After Monday, the next transit of Mercury will occur in 2019.
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
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.
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.
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.
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
Yep, dope haha!
“Apparent magnitude of the Sun as veiwed from the various Planets.” From an 1869 edition of The Atlas of Astronomy by Alexander Keith Johnston.
(David Rumsey Map Collection)
Saturn’s Rings
Telescope view of Jupiter and the 4 Galilean moons: Io, Europa, Ganymede, & Callisto.
The fantastical planets in Star Wars preceded our discovery of real planets outside our solar system…but fiction isn’t too far from the facts. When we send our spacecraft into the solar system and point our telescopes beyond, we often see things that seem taken right out of the Star Wars universe.
Saturn’s moon, Mimas, has become known as the “Death Star” moon because of how its 80-mile wide Herschel crater creates a resemblance to the Imperial battle station, especially when seen in this view from our Cassini spacecraft.
The most recently revealed exoplanet dubbed as Earth’s bigger, older cousin, Kepler-452b, might make a good stand-in for Coruscant — the high tech world seen in several Star Wars films whose surface is encased in a single, globe-spanning city. Kepler-452b belongs to a star system 1.5 billion years older than Earth’s! That would give any technologically adept species more than a billion-year jump ahead of us.
At 3,600 degrees Fahrenheit, CoRoT-7B is a HOT planet. Discovered in 2010 with France’s CoRoT satellite, it’s some 480 light-years away, and has a diameter 70% larger than Earth’s, with nearly five times the mass. Possibly the boiled-down remnant of a Saturn-sized planet, its orbit is so tight that its star looms much larger in its sky than our sun appears to us, keeping its sun-facing surface molten! This scorching planet orbiting close to its star could be a good analog for planet Mustafar from Star Wars.
Luke Skywalker’s home planet, Tatooine, is said to possess a harsh, desert environment, swept by sandstorms as it roasts under the glare of twin suns. Real exoplanets in the thrall of two or more suns are even harsher! Kepler-16b was the Kepler telescope’s first discovery of a planet in a “circumbinary” orbit (a.k.a, circling both stars, as opposed to just one, in a double star system). This planet, however, is likely cold, about the size of Saturn, and gaseous, though partly composed of rock.
Fictional Hoth is a frozen tundra that briefly serves as a base for the hidden Rebel Alliance. It’s also the nickname of real exoplanet OGLE-2005-BLG-390, a cold super-Earth whose surface temperature clocks in at minus 364 degrees Fahrenheit.
Kepler-22b, analog to the Star Wars planet Kamino…which was the birthplace of the army of clone soldiers, is a super-Earth that could be covered in a super ocean. The jury is still out on Kepler-22b’s true nature; at 2.4 times Earth’s radius, it might even be gaseous. But if the ocean world idea turns out to be right, we can envision a physically plausible Kamino-like planet.
Gas giants of all stripes populate the real exoplanet universe; in Star Wars, a gas giant called Bespin is home to a “Cloud City” actively involved in atmospheric mining. Mining the atmospheres of giant gas planets is a staple of science fiction. We too have examined the question, and found that gases such as helium-3 and hydrogen could theoretically be extracted from the atmospheres of Uranus and Neptune.
Endor, the forested realm of the Ewoks, orbits a gas giant. Exomoon detection is still in its infancy for scientists on Earth. However, a possible exomoon (a moon circling a distant planet) was observed in 2014 via microlensing. It will remain unconfirmed, however, since each microlensing event can be seen only once.
Discover more about exoplanets here: https://exoplanets.jpl.nasa.gov/
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Partial Solar Eclipse in White Light.
Credit: Unknown
Just a socially awkward college student with an interest in the celestial bodies in our universe.
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