2016 is almost over, and I don’t think any of us are going to miss it, but for the last
year astronomers have been working hard to catch up on what happened in the universe
during the almost 13.8 billion years we weren’t around for.
And they’ve made some record-breaking discoveries along the way, including some of the farthest,
faintest, and youngest objects in the universe.
Back in March, astronomers working with the Hubble Space Telescope reported that they’d
spotted the farthest galaxy we’ve ever seen, in a study published in The Astrophysical
Journal.
The galaxy is called GN-z11, and it’s at least 13.3 billion years old.
It’s so old that in the billions of years the light from that galaxy has taken to get
to Earth, the universe has expanded to the point that the galaxy is actually 32 billion
light years away.
To measure its distance, the researchers calculated how the wavelength of the light from the galaxy
has shifted.
Since the galaxy is moving away from us, the wavelength of its light is shifted toward
the longer, redder side of the spectrum, in what’s known as redshift.
Figuring out how much its light has been redshifted helps determine a galaxy’s distance.
The previous record holder had a redshift of 8.68, but this galaxy has a redshift of
11.1.
For comparison, the first stars ever born — some of the most distant objects in the
universe — would have a redshift of around 20.
But when Hubble’s more powerful successor, the James Webb Space Telescope, launches in
the fall of 2018, scientists should be able to detect galaxies with even higher redshifts
that are even farther away.
So hopefully GN-z11 won’t be the record-holder for long.
But astronomers found more than just the farthest galaxy we’ve ever seen this year.
They also found the faintest satellite galaxy we’ve ever seen.
So far, astronomers have discovered around 50 satellite galaxies that orbit the Milky
Way.
And in November, in another study published in The Astrophysical Journal, researchers
announced that they’d found the dimmest one yet.
It’s called Virgo I, and it has an absolute magnitude of -0.8.
Absolute magnitude is a measure of an object’s brightness from around 33 light years away,
and the higher the number, the dimmer the object.
For comparison, the Andromeda Galaxy, the closest major galaxy to the Milky Way, has
an absolute magnitude of -20.9 — meaning that from 33 light years away, it would be
almost as bright as the Sun is from Earth.
Whereas Virgo I would be about as bright as some of the brightest stars in the night sky.
Virgo I was discovered using the Subaru Telescope in Hawaii, which could spot the galaxy because
it has a larger lens and a larger field of view than other telescopes that have been
used to look for satellite galaxies before.
And its discovery is helping solve a problem: current theories about how the universe formed
predict that there should be a lot more satellite galaxies than we’ve seen.
But Virgo I’s discovery might mean there are hundreds more faint satellite galaxies
out there, so astronomers might soon be finding more galactic neighbors.
In addition to some of the oldest things we’ve ever found, we’ve also found the youngest
exoplanet we have ever seen.
Welcome to the planetary family, K2-33b.
The discovery is super useful for astronomers trying to learn more about the life cycles
of planets.
Most exoplanets we’ve seen so far are at least a billion years old, which is middle-aged
by planetary standards.
But this new planet is just a baby: It’s only 5 to 10 million years old.
The research took some of the best instruments we have, and the results were published in
the journal Nature in June.
First, NASA’s Kepler space telescope recorded periodic dimming in the star K2-33, which
is around 473 light years from Earth in the constellation Scorpius.
Then, the W.M.
Keck Observatory in Hawaii confirmed the dimming was being caused by a planet.
Then NASA’s Spitzer space telescope took more readings about the planet’s neighborhood,
while data from Kepler was used to confirm its orbit, size, and mass.
So it was a team effort.
To find the age of the planet, researchers first used its parent star’s density and
temperature to figure out the star’s age.
They found that the star is between 5 and 10 million years old, and since stars come
before planets, the planet has to be in that range, too.
The baby exoplanet is about six times larger than Earth, and it orbits its star about every
five days.
And researchers hope studying this new planet and others like it will teach us more about
how planets form.
What were your favorite space discoveries this year?
Let us know in the comments, and we’ll see you in 2017.
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