When Will the Sun Die and 6 Other Space Facts
1.
Each second about four million metric tons of matter is converted to energy within the
Sun’s core.
This gives the Sun a lifetime as a main sequence star of about 10 billion years with about
5 billion years to go.
2.
The surface temperature of the Sun is about 5780 K, which is equivalent to just under
10,000 F and 5,500 C. The temperature at the core is much hotter, close to 14 million Celsius
degrees or 25 million degrees Fahrenheit.
This extreme pressure and heat allow the Sun to generate its energy from nuclear fusion
at its core, fusing hydrogen nuclei into helium.
This nuclear fusion is self-regulating.
If the Sun’s diameter gets smaller while maintaining the same mass, the pressure at
the core increases creating more nuclear fusion which in turn causes it to expand.
If it expands maintaining the same mass, the pressure lessens in the core resulting in
less nuclear fusion going on.
So a natural equilibrium has resulted in this process with the Sun, though there are stars
that can be observed going through a process of massive expansion and contraction at very
steady rates.
3.
Sirius-A is the brightest extrasolar star visible to the naked eye from Earth, being
almost twice as bright as the second brightest, Canopus.
Sirius-A and Sirius-B combine to form a binary system and appear as one star to the naked
eye, though the vast majority of luminosity to the naked eye comes from Sirius-A, Sirius-B
being a white dwarf which is only around 30 AU (astronomical units) away from Sirius-A.
It is also theorized that there is a Sirius-C, but to date, this has not been proven.
Sirius A and B (and possibly C) combine to form a bright point known as Sirius or the
“Dog Star”, which is of course the inspiration for Sirius’ Black’s name in Harry Potter.
4.
Sirius-A is a white main sequence star (A1V) that is about twice the size of our Sun.
The extreme brightness from our point of view comes not so much because it is a particularly
bright star, but rather because it is only 8.6 light years away (2.6 parsecs).
That’s a really long ways away by standards of distance we normally deal with (about 50
trillion miles or so), but by galactic standards, it’s just next door and is one of our nearest
neighbors.
5.
One day on Mercury (i.e -the time it takes to rotate around its axis once) lasts 176
earth days.
A year on Mercury (i.e – the amount of time for Mercury to orbit the sun once) is 87.97
earth days.
In that sense, it remains daytime for a full year on Mercury and it stays night for one
full year also.
6.
Unlike Earth and most other planets in our solar system, Venus rotates clockwise.
The leading theory as to why this is the case is that it initially rotated counterclockwise,
but the planet flipped at some point.
7.
A white dwarf is a former star that is nearing the end of its life-cycle, with no further
nuclear fusion going on at its core.
Once most stars have used up the fuel at their core, they go into a red-giant or red super-giant
phase and expand to incredible sizes.
At the end of this phase, when the star has used up all its fuel that it can use via nuclear
fusion, if it has enough mass, it will extremely rapidly collapse and create one of the most
powerful explosions in the universe, the supernova.
The burst of energy from a single supernova can briefly out-shine an entirely galaxy full
of billions of stars.
If the red giant doesn’t have enough mass, it will simply collapse into a white dwarf
and spend a couple billion years slowly dimming as it gives off its stored energy.
Some star remnants are too small to begin with and so don’t ever go into a red giant
phase.
When they do go into their “red” phase, they are called “red dwarfs”.
However, the lifespan of these stars is longer than the universe has existed.
Thus, every star that will eventually become a red dwarf is still around today and has
not reached the red dwarf phase.
As a general rule with stars, the bigger and brighter it is, the faster it burns out.
The smaller it is, the longer it lives.