Gliese 710 and the Oort Cloud

Planet Earth and our Sun, as well as the other (now 7) planets are often depicted as larger and larger rings in space, but the Kuiper Belt and the Oort Cloud are made up of billions of comets, meteors and asteroids in three dimensions. But to get an idea of the true makeup of our Solar System, first consider that the entire mass of the gravitational influence of our Solar System is more than 100,000 times the orbit of the Earth, and shaped more like a sphere than a disk.

Light travels from the surface of the Sun to Earth in just over eight minutes, and to Neptune in four hours. The distance from the center of the Sun to the center of the Earth is defined as one Astronomical Unit, or AU. The edges of the Oort cloud are 50,000 AU from the Sun, which would be the radius, the diameter being 100,000 AU.

Within our planetary orbits lies the main asteroid belt. A handful of celestial bodies make up the vast bulk of the mass of this belt. This belt is more disc shaped. But further out from the orbit of our main planets is a much larger mass of billions of objects making up the spherically shaped Oort Cloud.

Here lies the problem with Gliese 710, and its expected approach to our Solar System. In 1.4 million years, Gliese 710 will have traveled over 60 light years at 50,000 mph towards the 100,000 Astronomical Unit diameter mass of our Solar System. While it is unlikely that calculations can be made accurately enough to predict whether Gliese 710, roughly more than half the mass of the Sun, will impact Earth, the Sun or any other planet, it only needs to travel within 25,000 AU or so of the Oort Cloud to start a chain reaction of events.

The billions of objects in the Oort cloud have had billions of years to settle into predictable orbits that keep the bulk of them from intersecting in orbits with Earth or the inner planets. But once gravitational forces from Gliese 710 act on the cloud, billions of objects will have these orbits stretched to different dimensions. While there orbits around the Solar System have periods of many thousands of years, there will at that point be billions of objects whose disrupted orbits over hundreds or thousands of years will now threaten the inner ranks of the Solar System.

Additionally, if Gliese 710 intersects more closely with the Sun, in the neighborhood of a few dozen AU or less, the impact on the orbits of the inner planets would be severe. Then there is the incredibly remote possibility that its path intersects with Earth or the Sun. That would surely be noticed.

Kepler-186f

Habitable Worlds



Other than Earth, Wikipedia lists 17 planets that could have sunshine and liquid water in our solar system, at distances ranging from 4.2 lightyears to 2500 lightyears away. If this were a complete list, we could break down our solar system into habitable areas of 2500 lightyears in diameter.

We would further consider that life could not be sustained in the interior of the Milky Way, due to Gamma Rays, Black Holes and other DNA squashing regularities of the interior.

So this would leave around 200 quadrants around the edge of the Milky Way, with several more in the arms such as where the Earth resides. Since no life has been detected in our local quadrant, other than Earth, we have little information with which to fill in the variables of the Drake Equation. Perhaps most of these quadrants have no life. But others contain two, or three civilizations.

We don’t know. Perhaps our own quadrant contains life that is closer to bacteria than to human. What is the likelihood that there is some primitive bacterial, stromatolite or even sponge like life in our quadrant. Some might say the odds are high.

But the odds of another civilization in our Milky Way are still difficult to ascertain. Two more civilizations? Five more? Certainly we have enough data to think it is unlikely that there are hundreds, or even a dozen civilizations in the Milky Way, and we still have no proof that there must be more than one.



Dark Matter

Scientists are searching for Wimps. Weakly interacting massive particles are a particle that we think is sub-atomic, accounts for 85% of matter in the universe, and we just can’t find the stuff.

The most obvious clues of dark matter began coming in as soon as we had telescopes capable of observing remote galaxies. In the 1920’s astronomers were fascinated by the Milky Way and the stars in the night sky, but indications arose that there were more galaxies than just the Milky Way.

With less powerful telescopes, we looked at the night sky and believed everything was a star. We knew that the Milky Way was a dense galaxy of stars, but it was the more powerful telescopes that showed us that some things that we thought were stars were other galaxies.

Lord Kelvin advanced the theory that objects unseen were subjecting gravitational pull within the Milky Way in a talk given in 1884. He speculated that a large percentage of star bodies were dark in the Milky Way. In 1906 Frenchman Henri Poincare advanced the notion of matiere obscure, or dark matter.

In the 1920’s Dutch astronomers Kapleyn and Oort further advanced the theory of Dark Matter and Fritz Zwicky in 1933 was working at the California Institute of Technology and had access to the Mount Wilson Observatory and the Palomar Observatory. He made records of the rotation of galaxies other than the Milky Way and advanced the idea that the rotation of galaxies would cause them to fly apart without Dark Matter.

Brightest Star

Let’s get super Sirius, the brightest star in the night sky is Sirius, 8 light years from Earth and twice the mass of the Sun. Known by many as the Dog Star, it is part of the constellation Canis Major which is south of the Zodiac belt.

In North America, winter is the best season for viewing Canis Major, also known as Greater Dog. The star Sirius is the nose of the dog. Early in the winter, Leo, Cancer and Gemini occupy the 2AM sky from Denver, along the ecliptical plane and towards the east. To the west in the Zodiac belt are Taurus, Aires and Pisces. In the middle of November in the middle of North America, Taurus dominates the night sky.

If your born between April 20 and May 21, Taurus is your sign. The Earth is on the opposite side of the sun from constellations from the opposite sphere of the Zodiac, like Sagittarius and Capricorn. During the course of a year, we gradually see the constellations from the twelve signs of the Zodiac dominate the equatorial plane of the night sky.

Sirius and the constellation Canis Major likewise are best viewed when the planet earth is on the correct side of the Sun. It is more easily seen from the southern hemisphere, although if you look toward the horizon or get on top of a mountain, you improve your chances. Gemini is next to Taurus, and may be the easiest ecliptic constellation to spot, as two bright stars at ten and 11 o’clock, and another bright star a four o’clock. It is supposed to be twins with their feet at the lower left and their heads at the upper right as you throw your head back while facing north.

Below and to the right of Gemini is Orion, and near that is the famous star Betelgeuse and below them more in line with Gemini is Canis Major. Sirius, the brightest star in the sky is the nose of the hound.

Brown Dwarf Stars

The planet Jupiter is a large mass of gasses, and brown dwarf stars are a large mass of gasses. But the difference lies a little bit in the diameter and a lot in the mass. Jupiter is a massive planet, 10 times as thick and a thousand times heavier than Earth. Mercury is the smallest planet, less than 1/2 the width of Earth and five percent the weight of Earth.

But in other solar systems, more massive planets than Jupiter have been discovered. These gas planets are getting near the size of a brown dwarf in their width. But they still do not have enough gas to be a brown dwarf. There is debate in the scientific community as to the difference between a really large gas planet and a brown dwarf. Brown dwarf stars do not have an active stellar fusion reaction in process, but the coolest brown dwarfs are as warm as Earth. This is peculiar because we know that the Earth gets heat from the Sun, and heat from internal nuclear reactions. Brown dwarfs seem to have neither the heat of a nearby star or the heat of a nuclear reaction to rely on.

In the cold depths of space, Jupiter has a surface one hundred degrees below zero. But we think the deepest interior of Jupiter is very hot. This is likely caused by the friction of compressed gasses, compacted by the force of gravity.

A brown dwarf has a surface far warmer than Jupiter. We think some brown dwarfs harbored some fusion at some point. We also believe they are cooling, and often a radiant brown dwarf is very young, much younger than Earth. Theories about the existence of brown dwarfs are decades old, but the best real astronomical evidence is within the last two decades.

We once thought there may be as many brown dwarfs as there are stars, but now we think stars outnumber brown dwarfs by at least five to one. But astronomically, stars give us a bright light to study, as opposed to only a tiny glow.

Black holes were once just a theory, and physicists studying gravity and the mass of large gas planets and small stars thought that something like a brown dwarf existed. Now we have seen them, but questions remain. How many of them lit fusion at a point, are cooler and darker ones still not seen? A key element to study in brown dwarfs is lithium. Lithium is present in some brown dwarfs, and may indicate some fusion at some point.

But if many more brown dwarfs are much older, much cooler, darker and harder to see, we don’t really know yet how much we know about brown dwarfs.

Wikipedia has more up to date information about brown dwarfs.