Animation: The Black Hole Collision That Created Today’s Gravitational Wave Announcement

Einstein was right. A hundred years ago, he predicted that really big objects in space can create ripples in the fabric of space-time. Today, scientists announced that these gravitational waves have been detected directly for the first time.

The confirmation came from the Laser Interferometer Gravitational-Wave Observatory (LIGO), based in Louisiana and Washington State.

The signal announced today came from the collision of two black holes. As Popular Science‘s Sophie Bushwick explains, the two black holes twirled around one another as they approached each other. The closer they got, the faster they spun, until they finally merged together into one giant black hole. The violent union released gravitational waves that LIGO detected as a “chirp” signal.

Below, this animation from Sketchfab user moroplogo explains what the black hole collision, and resulting gravity waves, may have looked like. Click around for a closer view.

A New Ninth Planet May Have Been Detected, Scientists Say

Sad that Pluto isn’t a planet anymore? Don’t worry, Caltech researchers may have discovered a new planet lurking in the outer reaches of our solar system.

They’re calling it “Planet Nine” for now. The planet, if it exists, has a mass 10 times that of Earth and takes between 10,000 and 20,000 years to orbit the sun.

An artist’s rendering of Planet Nine. Caltech/R. Hurt (IPAC)

Planet Nine has not actually been observed. Instead, evidence of the planet was discovered through mathematical modeling and computer simulations.

“Although we were initially quite skeptical that this planet could exist, as we continued to investigate its orbit and what it would mean for the outer solar system, we become increasingly convinced that it is out there,” Konstantin Batygin, an assistant professor of planetary science at Caltech, said in a statement.

The research from Batygin and Mike Brown, whose discoveries led to the downgrading of Pluto to a “dwarf planet,” was published Wednesday in The Astronomical Journal.

It all started in 2014 with the investigation of 13 objects in the Kuiper Belt — a region of the solar system beyond Neptune filled with comets and other icy bodies, as well as dwarf planets including Pluto.

Six of those objects had an orbit that suggested they were circling some distant object, which the researchers now believe is the ninth planet in our solar system. Although they believe they know the planet’s orbit, they hope to actually locate it using a large telescope.

“This would be a real ninth planet,” Brown said. “There have only been two true planets discovered since ancient times, and this would be a third. It’s a pretty substantial chunk of our solar system that’s still out there to be found, which is pretty exciting.”

Milky Way

 

MILKY WAY

The Milky Way is a galaxy that contains our Solar System.[18][19][20][nb 1] Its name “milky” is derived from its appearance as a dim glowing band arching across the night sky whose individual stars cannot be distinguished by the naked eye. The term “Milky Way” is a translation of the Latin via lactea, from the Greek γαλαξίας κύκλος (galaxías kýklos, “milky circle”).[21][22][23] From Earth the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis,[24] observations by Edwin Hubble showed that the Milky Way is just one of many galaxies—now known to number in the billions.[25]

The Milky Way is a barred spiral galaxy that has a diameter usually considered to be roughly 100,000–120,000 light-years[26] but may be 150,000–180,000 light-years.[27] The Milky Way is estimated to contain 200–400 billion stars,[28] although this number may be as high as one trillion.[29] There are probably at least 100 billion planets in the Milky Way.[30][31] The Solar System is located within the disk, about 27,000 light-years from the Galactic Center, on the inner edge of one of the spiral-shaped concentrations of gas and dust called the Orion Arm. The stars in the inner ≈10,000 light-years form a bulge and one or more bars that radiate from the bulge. The very center is marked by an intense radio source, named Sagittarius A*, which is likely to be a supermassive black hole.

Stars and gases at a wide range of distances from the Galactic Center orbit at approximately 220 kilometers per second. The constant rotation speed contradicts the laws of Keplerian dynamics and suggests that much of the mass of the Milky Way does not emit or absorb electromagnetic radiation. This mass has been given the name “dark matter”.[32] The rotational period is about 240 million years at the position of the Sun.[15] The Milky Way as a whole is moving at a velocity of approximately 600 km per second with respect to extragalactic frames of reference. The oldest stars in the Milky Way are nearly as old as the Universe itself and thus must have formed shortly after the Big Bang.[9]

The Milky Way has several satellite galaxies and is part of the Local Group of galaxies, which is a component of the Virgo Supercluster, which again is a component of the Laniakea Supercluster.
OBSERVATION DATA

Type Sb, Sbc, or SB(rs)bc[1][2] (barred spiral galaxy)

Diameter 100–180 kly (31–55 kpc)[3]

Thickness of thin stellar disk ≈2 kly (0.6 kpc)[4][5]

Number of stars 200–400 billion (3×1011 ±1×1011)[6][7][8]

Oldest known star ≥13.7 Gyr[9]

Mass 0.8–1.5×1012 M☉[10][11][12]

Angular momentum ≈1×1067 J s[13]

Sun’s distance to Galactic Center 27.2 ± 1.1 kly (8.34 ± 0.34 kpc)[14]

Sun’s Galactic rotation period 240 Myr[15]

Spiral pattern rotation period 220–360 Myr[16]

Bar pattern rotation period 100–120 Myr[16]

Speed relative to CMB rest frame 552 ± 6 km/s[17]

Escape velocity at Sun’s position 550 km/s[12]

Dark matter density at Sun’s position