- 2942 - STAR OF BETHLEHEM - December 21,2020. This Review covers the depths of science to the depths of religion. We need both faith and knowledge. Gravitational waves are our newest technology to explore the universe with science. The Star of Bethlehem is the story of the birth of Christ and the stars are again in alignment this year, 2020.
------------------ 2942 - STAR OF BETHLEHEM - December 21,2020
- On August 17, 2017, a gravitational wave traveling across space-time, betrayed the cataclysmic merger of two neutron stars out in the cosmos to scientists here on Earth. The initial signal was caught by the “Laser Interferometer Gravitational-Wave Observatory” (LOGO) and the “Virgo detector“.
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- Shortly after, 70 other observatories across the world confirmed the colossal merger. The fact that our detectors had managed to make multiple observations of one cosmic collision was unprecedented to astronomy.
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- By combining all the data gathered from this neutron-star merger astronomers have made the most accurate measurement yet of a fundamental property of the universe: The rate at which the universe is expanding is called the “Hubble Constant of expansion“.
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- Since the Big Bang birthed the universe around 13.7 billion years ago, the universe has continued to expand. The universe expansion rate, measured through the Hubble Constant, is calculated in one of two ways:
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-------------------- Tracking the distances between galaxies and the Earth over time. Looking at the light from nearby variable stars,
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-------------------- The form of radiation called the “cosmic microwave background“, in different galaxies.
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- These two measures are at odds with each other because the two methods produce different results, and scientists are not sure which is right.
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- The merger of two neutron stars produced a host of astronomical observations in different mediums. Neutron stars are the super dense remains of stars which exploded in supernovae. These stars have a mass about 1.4 times that of the Sun, but it is all packed tightly into a small, dense sphere the size of a city.
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- Scientists have never been able to recreate in a lab matter as dense as that found in neutron stars. As a result, observing explosive mergers between these stellar beings is the only way scientists can observe the properties of matter in this strange state.
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- These two neutron stars spiraled around each other, attracted by each other's gravitational pull, and emitted gravitational waves that lasted for about 100 seconds. As the two stars collided, they emitted a flash of light in the form of gamma rays, which was observable from Earth around two seconds after the gravitational waves hit our LIGO detectors.
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- Scientists around the world also made X-ray, ultraviolet, optical, infrared and radio waves observations of the merger, adding to the data trove. Using this host of data, the researchers were able to measure the mass and radius of each neutron star, and determined how far they were from Earth.
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- Astronomers were then able to compare the stars' distance to the apparent rate of recession away from Earth. The results do favor the cosmic microwave background method results.
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As scientists struggle to understand the universe we exist within, some of the most fundamental questions about the nature of the universe remain obscure. How big is it? How did it come to be? Filled with galaxies, stars, planets, dust, and gas, the cosmos is full of extreme features extreme masses, extreme structures, and extreme features.
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- The answers to these questions have eluded scientists for hundreds of years. How hot is the universe? The average temperature of the hot gases in the large-scale structures, including galaxies and galaxy clusters, of the universe is 2 million Kelvin. These gases make up the bulk of the visible matter in the universe.
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- Different, individual objects in the universe have different temperatures. The internal temperatures of the Sun reach 15,700,000 degrees Kelvin. The Cosmic Microwave Background (CMB) radiation, the stuff left over from the Big Bang, is only 2.75 Kelvin, however.
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- Scientists believe that the temperature of the universe may have been nearly infinite at the moment of Big Bang. Unlike now, the universe was probably almost completely homogeneous composed of a quark-gluon soup out of which protons and neutrons eventually emerged as the soup expanded and cooled.
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- When the universe began to rapidly expand after the Big Bang 13,800,000,000 years ago, the temperature cooled dramatically and quickly. As the universe became less homogenous and differentiated into the structures that are recognizable today, such as galaxies, temperature regimes throughout the universe became more diverse.
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- The CMB radiation dropped from 10,000 Kelvin to the contemporary 2.75 Kelvin. Collapsing gas clouds formed stars which heated up when nuclear reactions began to transpire in their interiors.
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- The temperature of the CMB cooled as it expanded because the expansion process stretches out the wavelengths of the photons in the CMB. Longer wavelengths are associated with less energy, and thus, a lower temperature.
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- This same expansion process created a new source of heat due to the action of gravitational forces. The temperature of the Cosmic Microwave Background can help reveal how temperature has changed in the universe over time. As the Universe evolves, gravity pulls dark matter and gas in space together into galaxies and clusters of galaxies.
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- The drag is violent, so violent that more and more gas is shocked and heated up. This process has been responsible for tripling the average temperature of the hot gases in the universe over the last 8 billion years.
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- Researchers can measure the temperature of the hot gases in the large-scale structures of the universe by studying distortions in photons that travel to Earth from the CMB. As the photons pass through hot gas, they take on some of the energy from the gas. They can detect and measure this change, using it to calculate the temperature of the gases.
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- This is not necessarily the same as knowing the temperature of everything in the universe. Studying the temperature of the universe is an important part cosmologist as they to understand the origin of the universe and how it changes over time.
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- Gaining new insights into the temperature regimes of the universe helps them test and develop cosmological models. Heat has to come from some kind of physical or energetic process. Evaluating temperature data in the context of the known laws of physics, can help researchers develop theories that best explain how the universe works.
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- At the other extreme closer to our end of the Universe this is the best month to see the Full Moon, a meteor shower, or Mars. This week in December 21, 2020, you can see a rare celestial encounter between Jupiter and Saturn, one that has not occurred in nearly 400 years, when the pair will appear to shine as one, bright star in the night sky on Monday.
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- Jupiter and Saturn's respective orbits will align on Monday, bringing the two planets the closest they have been in nearly 400 years. This rare alignment hasn't occurred over night in more than 800 years.
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- The planets' alignment will take place on the night of winter solstice, the longest night of the year. It takes Jupiter 12 years to orbit the Sun. Saturn takes a slower, more distant route that takes the planet 29 years to complete.
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- In this rare alignment of their orbits, Jupiter essentially laps Saturn, speeding up past the gas giant in their respective trips around the Sun. You can imagine the solar system to be a racetrack, with each of the planets as a runner in their own lane and the Earth toward the center of the stadium. From our vantage point, we’ll be able to be to see Jupiter on the inside lane, approaching Saturn all month and finally overtaking it on December 21.
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- The planets' conjunction takes place every 20 years. But because of where we are in our orbit, this is the closest they will appear to us from Earth since 1623. The last time the conjunction appeared so close to Earth in the night sky was 1226.
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- When it happens, the two planets will look as though they are incredibly close to one another, appearing as one single bright spot in the sky. But the actual physical distance between the two planets will not have changed.
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- Rather, it's an optical illusion. The planets are not on a perfect orbital plane, and their respective orbits around the Sun are slightly inclined to one another.
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- When the conditions are just right, as they are this year, the planets appear at their chummiest in several hundred years. But in reality, they are still millions of miles apart.
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- To view this spectacular display in the sky, look towards the southwest shortly after sunset. You must also have a clear view of the sky as the two planets are setting, so it is best to get as high up as you can. Even tree tops might interfere with your view.
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- Jupiter will appear as a bright star and be easily visible, while Saturn will be a little less bright, visible slightly above and to the left of Jupiter. It’s an unmistakable sight as soon as you look towards the southwest. They’re one very bright light and one quite bright light very close to each other.
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- You can stare at this rare celestial event with the naked eye, but a telescope may enable you to see Jupiter's larger moons. The next time these two planets will appear this close in the night sky will be on March 15, 2080 so be sure to look up on Monday night if you don't want to miss it.
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December 18, 2020 STAR OF BETHLEHEM - December 21,2020 2942
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--------------------- --- Friday, December 18, 2020 ---------------------------
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