Anish Moonka@anishmoonka
Went down the rabbit hole on this. You traveled about 17 million kilometers in your sleep last night, roughly 45 trips to the Moon in a single nap.
The 600 km/s in this post is a real number. Satellites measured it by comparing our motion against the faint glow left over from the birth of the universe. But the speed alone is only half the picture. Where we're headed is the part that got me.
Your body is riding four things at four different speeds, all at once. Earth spins at 1,670 km/h. Earth whips around the Sun at 107,000 km/h. The Sun circles the center of our galaxy at 828,000 km/h. And the Milky Way is tearing through space at 2.1 million km/h. You don't feel any of it.
All the galaxies near us, about 100,000 of them, are being dragged toward one spot. Astronomers call it the Great Attractor. It sits about 250 million light-years away and has the combined gravitational pull of thousands of galaxies. We can't see it, because our own galaxy's dust and stars block the view completely. That whole section of sky is so obscured that astronomers named it "the Zone of Avoidance." We only know something is there because every galaxy near us curves toward the same blind spot. Infrared and X-ray telescopes eventually confirmed a massive pile-up of galaxies hiding behind the curtain.
I kept digging. The Great Attractor is itself being yanked toward something even larger called the Shapley Supercluster, about 650 million light-years out. The thing pulling us is also being pulled.
In 2014, an astronomer at the University of Hawaii named Brent Tully mapped all these galaxy flows and realized we're part of one enormous structure. He named it Laniakea (Hawaiian for "immense heaven"). 500 million light-years wide, about 100,000 galaxies, all draining toward the same gravitational low point like water running downhill. But Laniakea won't hold together. The expansion of the universe is speeding up, slowly ripping the whole structure apart. Our cosmic address has an expiration date.
While all this plays out, the Milky Way is also drifting toward the Andromeda galaxy at about 400,000 km/h. Those two will merge in roughly 4 billion years. But that crash is happening at a fifth of the speed we're falling toward the Great Attractor. Even the collision is a subplot.
You went to bed, stayed completely still for 8 hours, and woke up 17 million km from where you fell asleep. Tonight you'll do it again.