How a giant black hole races through the cosmos, creating a stream of stars

 When I look up at the starry sky on a beautiful spring evening, much of it is familiar. For example, I see the distinctive 'W' of the constellation Cassiopeia, the saucepan of the Big Dipper or the bright dot of our neighboring planet Venus. Then grab a star map and you can even find very precise celestial locations at which you, as a hobbyist, can point a telescope to see galaxies or fanning gas nebulae.

All this gives the feeling that we know that night sky a little bit. That we numbered everything, gave it names and checked it off on our star charts. However, that is an erroneous idea, as it turned out again recently, when Nasa reported something special. Something that the Hubble Space Telescope had seen in the depths of the Universe with its much sharper than human eye.

One of the photos from the telescope showed a small streak of light. Such an irrelevant-looking thing that at first scientists thought they were dealing with a speck, an anomaly, perhaps a stray sliver of cosmic rays that had collided with Hubble's cameras. Until it turned out that that stripe is something very special: a supermassive black hole racing through space with a stream of stars in its wake.

It is the first time that scientists have seen such a huge hole moving alone through the universe, they write in the journal The Astrophysical Journal Letters . You normally find such cosmic monsters in the center of galaxies. Our own home galaxy, the Milky Way, also has one: Saggitarius A*, photographed last year by the Event Horizon telescope. Astronomers have long thought that when two galaxies collide, a supermassive black hole in them might eject. No one had ever seen anything like it before, but now it seemed right.

That little dash is really huge, with all the staggering numbers associated with cosmic discoveries. For example, the black hole has the mass of twenty million suns and moves through the universe at a mere 5.7 million kilometers per hour. So fast that it can fly from Earth to the Moon in 4 minutes.

Such a monster moving through the universe at a killer pace is a terrifying thought, but at the same time turns out to be a source of cosmic creation. As the black hole collides with the gas in front of it, it is compressed in such a way that new stars are formed. That's the source of the stream of stars dragging the colossus: a tail 200,000 light-years long, twice the diameter of the Milky Way.

This bizarre spectacle takes place in a small part of the night sky, somewhere between all those familiar stars and planets. An illustration that what we see there is really only the minuscule vanguard of everything else that the cosmos hides from the naked eye.

improve alter emerge occur freeze rate increase wind exhibit constitute prefer halt turn recall dispose consist