Imagine Captain Kirk, Spock and Dr. McCoy beaming down to the surface of the planet Jupiter from the orbiting Enterprise. No sooner would they materialize when poof ... they would plummet directly toward the center of the planet, screaming the entire way down. That is, until they were crushed by the tremendous pressure or immolated by the intense heat.
Jupiter
There is no surface on Jupiter, as it's made up virtually entirely of gases. Estimates vary slightly, but approximately 90% of the composition of the planet is hydrogen, with the remaining 10% helium and trace elements. These percentages are very similar to the composition of the Sun itself. There may be a rocky core approximately the size of the Earth at its center. Speaking of the center, it's known that the planet generates over twice as much energy as it receives from the sun and as such, the thermodynamic relationship between gravity, pressure and heat results in a core temperature of approximately 54,000 degrees Fahrenheit. By comparison, the Earth's core has an estimated temperature of 9,000 degrees Fahrenheit. Coincidentally, so does the surface of the Sun.
In summary, Jupiter has the following traits similar to those of the Sun:
- Comprised of mostly hydrogen and helium
- Massive gravity
- Substantial heat generation
- No solid surface
- Strong magnetic field
- Turbulent weather
These traits beget the following question: how close to becoming a star did Jupiter actually get?
Brown dwarf
Per the Merriam-Webster Dictionary, a brown dwarf is defined as follows: a celestial object that is much smaller than a normal star and has insufficient mass to sustain nuclear fusion but that is hot enough to radiate energy especially at infrared wavelengths.
Brown dwarfs, in summary, are generally considered to be failed stars: not large enough in terms of mass to spark nuclear fusion, but they experience chemical differentiation with depth and have convective flows. They were first theorized in the 1960's, with the first discovery in 1988. Our understanding of them is evolving; when first theorized, the lowest end of the size spectrum was considered to be 75 Jupiters. Just this year, however, the coolest brown dwarf ever discovered was found, with a mass of just six times that of Jupiter. It is not yet known what the low-end limit with respect to mass must be.
The Subaru Telescope in Hawaii made the discovery of the new brown dwarf, and the press release on their official web site stated: "Its mass is comparable to those of giant planets, yet it doesn't circle a star," said Aleks Scholz of the Dublin Institute for Advanced Studies in Ireland. Scholz is lead author of one upcoming paper reporting the team's findings. "How it formed is a mystery."
Failed brown dwarf
Mass is the key to the birth of either a star, a brown dwarf or merely a planet. Jupiter certainly had nowhere near the mass for the interstellar gas to collapse with sufficient gravitational force to form a star. However, given the expansion of the conventionally-considered lower limit on the size required to form a brown dwarf, it may not be a stretch to consider Jupiter to be a failed brown dwarf — in a netherworld between conventional planet and that of a protostar — given how our understanding of the latter is changing rapidly.
What about the Other Gas Giants?
Saturn is also a giant gas planet, but despite being less than 20% smaller as measured by diameter, is less than one-third as massive as Jupiter. Thus, although it, too, radiates significantly more heat into space than it receives from the Sun, it produces significantly less: the core temperature is estimated to be approximately 21,000 degrees, or about a third of the core temperature of Jupiter. Uranus is less than half the diameter of Saturn, but mysteriously, has no internal heat source. Neptune's internal temperature is approximately 12,600 degrees. Although Jupiter may or may not have been close to the mass necessary to develop into a brown dwarf, none of the others appear to be able to make that claim.
Earth Could Have Been Tatooine
In the Star Wars series, the fictional planet Tatooine was part of a binary star system. Such systems, evidence suggests, may be the norm in the universe, not the exception. Were the cloud of gas that eventually became Jupiter about a hundred times or so bigger, we might be watching two sunrises and two sunsets every day. Global warming would take on an entirely new meaning.
Sources
- StarrySkies.com
- NinePlanets.org
- HyperPhysics.phy-astr.gsu.edu
- News.Softpedia.com
- CoolCosmos.jpac.caltech.edu
- UniverseToday.com
- Space.com
- Naoj.org
- SpaceToday.org
- Science.jrank.org
- csep10.physics.utk.edu
Walter McLaughlin - I am a 47-year old commercial banker living in the Seattle area. I am an avid sports fan, but also greatly enjoy writing satirical, ...
