When it comes to sustaining life, some planets in our solar system are too close to the sun
and some are too far away, but Earth is just right.
How did we get so lucky?
Turns out we may not be so special.
Like, at all.
Hello again, I’m Julian and this is DNews.
Earth is pretty great.
It’s got huge bodies of water just lying all over it, and they allowed life as we know
it to exist and thrive.
So when we’re looking for life out there among the stars, liquid water is the holy
grail.
Not all planets can have liquid water, it depends on how far the planet is from its
star.
Too close and the water evaporates, too far and it all freezes.
In between is the Habitable Zone.
The zone’s size and location varies from star to star depending on its luminosity.
Luminosity is a function of the star’s temperature and size.
If it’s hot and/or big, it’s more luminous and the habitable zone is farther away and
bigger.
In 2009 NASA launched the Kepler space telescope to scan the night sky for Goldilocks planets
orbiting other stars, and the numbers scientists are extrapolating from its findings are pretty
staggering.
The problem with the way Kepler works is, to find planets they need to be big, fairly
close to the star, and pass between us and the star.
If a planet is farther away in the habitable zone, Kepler probably can’t see it.
To get around this problem researchers from the Australian National University and the
Niels Bohr Institute in Copenhagen applied the Titius-Bode law to a sample of 151 stars
Kepler had found with 3 to 6 planets.
The Titius-Bode law was proposed in 1766 by Johann Daniel Titius and described mathematically
by Johann Ellert Bode in 1772.
Yes, everyone was named Johann back then.
It predicts the orbits of planets in stable planetary systems, but “law” is a bit
of a strong word and it’s really more a rule of thumb.
It was used to predict the orbit of Uranus before it was discovered in 1781, but overestimated
what Neptune’s orbit should be by about 10 AUs.
Still, there’s a high probability that a planetary system will follow the rule and
indeed 124 of the 151 systems researchers looked at were bang on.
So if more planets were added following Bode’s law, the stars should have between 1 and 3
each.
To be more conservative, 31 of the star systems either already had observable planets in the
habitable zone, or only needed one more planet to have one.
Researchers predict an average of 2 planets in the habitable zone around these stars,
and furthermore a “good share” of those will be solid and could host liquid water.
To see if the idea holds water the astronomers are looking for 77 predicted planets that
Kepler should be able to see in 40 star systems.
A “good share” of 62 planets out of 151 solar systems may not sound like much, but
remember the universe is a pretty big place.
In just our galaxy, that translates to potentially hospitable planets numbering in the billions.
With a B.
Once we find the planets though, the next step is finding water.
Trace covers how we do that down here.
Check the description for the link if you’re on your mobile.
So, potentially billions of planets that could sustain life right here in our back yard.
Still think we’re alone?
Let us know in the comments or find me on twitter @JHug00 and I’ll see you next time
on DNews.