Intergalactic terrors
The moon may disappear into the dark night sky, the stars engulf one another, and comets may scatter our inner solar system.
Josh Colwell, UCF Pegasus Professor and co-host of the podcast Walkabout the Galaxy, explores the disturbing cosmic entities that dwell within our universe.
Each year, the moon recedes 3.8 centimeters from our Earth, caused by a tidal interaction. From this interaction, the moon takes away bits and pieces of Earth’s angular momentum, slowing Earth’s rotation and slowly drifting away and eventually taking solar eclipses with it.
“Because as the moon gets further away, it's smaller in the sky, which means it's going to have a harder time fully covering the sun,” Colwell said. “So, at some point, those solar eclipses will get less and less frequent, because more and more of them will be annular or partial solar eclipses. But it's at least hundreds of millions of years before the last total solar eclipse.”
While those on Earth have nothing to worry about, future inhabitants on Mars face a bigger threat in 10 million to 100 million years as the opposite effect will send its moon, Phobos, crashing towards the surface of the dusty planet.
And aside from lunar impacts, another threat occurs among the stars – those with cannibalistic tendencies.
Stars are typically in multi-star relationships, meaning two or three stars orbit and interact closely with one another, Colwell said. Bigger stars in the sequence tend to be ‘gas guzzlers’, swelling up and eventually becoming giant stars.
“If your neighbor star was a little bit less massive, it will not have become a red giant,” Colwell said. “At that same time, it'll still be merrily burning along what we call the main sequence. When that neighbor star, your other star in the system, swells up, it can engulf the other star in the system. You can have, if they survive, you can have one star basically pulling material off of the other.”
In 4 billion to 5 billion years in a similar manner, our Sun will swell up by a few hundred times, but we may not be completely doomed, Colwell said.
Recent studies show that as the Sun expands, it will lose material from strong stellar winds as the Earth’s orbit gradually expands at a safe distance, Colwell said. While it may not incinerate the Earth, it could make the planet and cold and unpleasant place to be in the next billions of years.
In the near future, about 50 to 100 years, the Sun’s stellar neighbors may stir up commotion in our Orc Cloud, the reservoir of comets on the outskirts of our solar system, and trigger comet showers within our inner solar system. Colwell said these showers could increase major impacts on the Earth and may explain past impacts that have caused mass extinctions.
But not to worry, as Colwell said the mapping, identification and tracking of these near-earth objects’ orbits are being monitored by revolutionary equipment and tools.
“We've made tremendous strides in identifying the population of these objects, mapping them,” Colwell said. “There are new space observatories that are being planned that will be launched this decade to map those out. It's not something like, once you're done you check the box and say, ‘Okay, I don't need to worry about this anymore.’ Their orbits are always evolving, and so it has to be a constant monitoring process.”
How can a black hole have a heart?
Similar to the heartbeat in Poe’s floorboards, one cosmic phenomenon is also thumping deep in our universe. If black holes weren’t scary enough, scientists have detected a heartbeat within some black holes.
Dr. Stephen Eikenberry, UCF applied optics professor and physics professor, tells the tale of the accidental detection of black hole X-rays like those in medical tests. The first X-ray astronomy satellite mission, Uhuru, initially aimed to understand the composition of the moon via scattered light; instead, they detected the first X-ray binary from the constellation, Scorpius.
Equipped with a regular telescope, scientists observed what they thought was just an X-ray dense star, called Cygnus X-1, Eikenberry said. This galactic X-ray source, unexplainable by cosmic possibilities, became the first identified black hole.
Eikenberry said although these X-ray dense phenomena have been detected fairly often, only recently have there been two with this unique pulsation. These black holes shoot out streams of highly magnetized plasma as the surrounding material, or accretion disk, fragments and falls into the deep center, creating heart-like pulses.
“What we can tell when we look at that source is sometimes it looks like a human heart EKG, so that's why we call them heartbeats— there's a little blip about once a second, it just goes, blip, blip, blip,” Eikenberry said. “It might be once a second, once every few seconds, something like that, but it's sort of a quasi-regular beating of some kind of signal coming from the black hole.”
Scientists have only been studying these heartbeats, or “quasi periodic oscillations” for a few years, leaving many questions unanswered. How these vampiric anomalies go thump in the night depends on the right circumstances between the material flowing inside and the victim companion star the black hole is feeding on.
“It's pulling material off of its neighbors, or off of, in a case of a supermassive black hole, a whole bunch,” Eikenberry said. “It can even eat entire stars in one gulp. These are monsters out there that are definitely sucking the life out of their neighbor stars and using that to survive and make the bright X-ray light we see.”
Luckily these black holes are very far away, so we won’t have to worry about falling victim to the vampiric entities any time soon, Eikenberry said.
“We can use them to study the most extreme conditions in the universe, and this becomes a real testing ground for us to probe the laws of physics as we know it,” Eikenberry said. “So, we're using them to try to check out Einstein's theory of general relativity in the most extreme cases that we can where we're more likely to see if there are any flaws or exceptions to his physical description of the universe.”
