The broad spectrum sounds recorded in the summer of 1997 are consistent with icequakes generated by large icebergs as they crack and fracture. NOAA hydrophones deployed in the Scotia Sea detected numerous icequakes with spectrograms very similar to “Bloop”. The icequakes were used to acoustically track iceberg A53a as it disintegrated near South Georgia Island in early 2008. Icequakes are of sufficient amplitude to be detected on multiple sensors at a range of over 5000 km. Based on the arrival azimuth, the iceberg(s) generating “Bloop” most likely were between Bransfield Straits and the Ross Sea, or possibly at Cape Adare, a well know source of cryogenic signals.
What if the Earth had two, or more, moons? While the prospect may appeal to science fiction writers and romantics, life on the surface, to put it mildly, would be far less stable than it is now. If there were life on the surface in the first place, that is.
If we had a second moon show up, things would change in a hurry. Our tides would go haywire and cause massive storms, volcanoes and earthquakes to pop up from the added forces put on the Earth’s crust. Unfortunately for most things alive on Earth at the time, this would mean chaos, death and possible extinction. That includes us, but maybe not the bacteria or cockroaches. The second moon would also cause chaos on our first moon, causing similar geologic changes, although not as severe since Moon #1 is a lot more dormant on the inside.
And here’s another reason to be thankful Earth has only the one natural satellite. Like many of the other planets in the solar system, Uranus has several (27 actually) moons, or at least it does for now. At some point the future though a number of them are slated to collide with each other, events that will cause all sorts of chaos:
In the first act, Cupid smacks into the larger moon Belinda sometime between 1000 and 10 million years from now, depending on initial conditions. What happens next depends a lot on the moons’ as-yet-unknown compositions. They could bounce off each other, stick together or break apart into tiny pieces. In some settings, French and Showalter assume Cupid and Belinda will merge to form a single moon called CupBel. From there, the next pair of doomed moons is Cressida and Desdemona, fated to crash in 100,000 to 10 million years. If those moons merge, the resulting body, Cresdemona, takes out the moon Juliet, and CupBel collides with Perdita.
Since 1972 seven orbiting Landsat satellites have taken turns to photograph the Earth’s surface. Needless to say if they could talk they’d be able to tell a few stories, as seen by this series of then and now photos, showing how cities such as Tokyo, Chicago, Istanbul, and Santiago have changed over the last forty years.
The image of Santiago (move the centre dividing slider back and forth to see the contrasts) is especially interesting. Note the presence of what looks to be snow/ice in the bottom right-hand corner of the 1985 image and then compare the same region with the 2010 photo.
Place a satellite into a geosynchronous orbit above the Earth, being 36,000 kilometres or so up, and it will, all things remaining equal (a big ask at the best of times, but that’s another story), remain there perpetually. As it is there are hundreds of such probes, many no longer functioning, floating in this zone, giving rise to the term “graveyard orbit”.
What better place then to store a record of artworks created on Earth that will still be about long, long, after life on the surface has disappeared?
That’s the thinking of behind US artist Trevor Paglen’s “The Last Pictures” project, that will see trillions of images depicting artworks from across the globe, stored on very long life discs, aboard a satellite that will be launched into a permanent graveyard orbit this September.
Life would be: Migratory and on shorter day-night cycles, if existent at all. Huge tides generated by the moon – which orbited much closer to Earth when it formed – washed the chemical building blocks for life from land into the oceans and helped “stir up the primordial soup,” said Neil Comins, a professor of physics at the University of Maine.
Everyone knows that alien spaceships don’t have to clumsily lumber down a runway before takeoff – they lift off vertically with perfect balance and then propel in whatever direction they choose. Helicopters have the vertical takeoff aspect down, but even the best designs can be foiled by ground landings, as was the stealthy MH-60 Black Hawk helicopter used in the raid that killed Osama bin Laden. A Discrotor helicopter is actually a helicopter/airplane blend that can take off and land vertically, but also enter into high-speed flying mode by retracting its rotating blades and relying on fixed wings, allowing it to move like a plane. Will that help against aliens? We certainly hope so.
A difficult question to address really, considering we’d likely have no idea at all as to what we were up against.
Geologists have long known that Earth’s core, some 1,800 miles beneath our feet, is a dense, chemically doped ball of iron roughly the size of Mars and every bit as alien. It’s a place where pressures bear down with the weight of 3.5 million atmospheres, like 3.5 million skies falling at once on your head, and where temperatures reach 10,000 degrees Fahrenheit – as hot as the surface of the Sun. It’s a place where the term “ironclad agreement” has no meaning, since iron can’t even agree with itself on what form to take. It’s a fluid, it’s a solid, it’s twisting and spiraling like liquid confetti.
Just over 70 per cent of the Earth’s surface is covered with water, yet if that were amassed – together with every last drop on the planet, lakes, rivers, plants, etc, even the water that makes up us – into a single body, it would form a sphere with a diameter of almost 1,400 kilometres, which is about 40 percent of the Moon’s diameter.