The Alpha Centauri System

The Alpha Centauri system is a very typical star system. It is the closest system to the Earth and gets a lot of attention from us since it is relatively easy to observe. Like most star systems, its birthing process produced more than one star; it has three.

Alpha Centauri A and B are Sun-like yellow dwarf stars and form a binary star system. They rotate around a common point and are approximately as close to each other as Saturn and the Sun. The third star, Alpha Centauri C (also called Proxima Centauri) is a Class M red dwarf. It is not clear if Proxima Centauri is rotating around the two Alpha Centauri stars or just happens to be near them.

Is There Life in the Alpha Centauri System?

The most exciting about Proxima Centauri is that it has confirmed planets, one of which is an Earth-like planet within what is called the “habitable zone”, namely it may be the right temperature to support life as we know it. Unfortunately, Proxima Centauri is prone to emitting massive flares of energy at random intervals, which may render the planet unlivable.

What would it be like to live in a three-star solar system?

Alpha Centauri A and B may also have planets (the astronomers are not yet sure about this). If you lived on a planet orbiting Alpha Centauri A, it would appear similar to the Sun viewed from Earth, rising and setting on a regular daily schedule.

Alpha Centauri B would periodically appear in the sky, like the Moon, but much brighter. The two stars have an eccentric orbit that takes around 80 years to complete. At their closest approach, the secondary lighting from Alpha Centauri B on your planet would be as bright as typical indoor lighting. At their furthest approach, the light would be more like a dim porch light. Proxima Centauri, being a dim red dwarf, would just look like any other star in the sky.

Can we visit Alpha Centauri?

NASA is planning to send an unmanned spacecraft to the Alpha Centauri system in 2069, but it would probably take around 44 years before it arrived and another 4 years for its information to start arriving back at Earth, namely in the year 2117.

The Breakthrough Starshot program could, in theory, travel to the Alpha Centauri system in around 20 years. The Starshot program, which was co-founded by Stephen Hawking in 2016, is trying to create light sail spacecraft that can move at around 20% of the speed of light.

Suns are created by gravity. Clouds of debris and gas floating in space are slowly pulled together by gravity. If a sufficient amount of matter is compressed together by gravity, the process of fusion will begin and a new star will be born.

The Orion Nebula is a well-studied “birthing ground” of stars. It is a massive cloud of dust and matter that is slowly clumping together into new stars. Computer simulations based on observations of stars being born in the Orion Nebula suggest that first, a dense, spinning cloud of debris forms, and then in most cases, it breaks up into two or three clumps that develop into stars. These simulations explain why most stars seem to occur in pairs or triplets, like the Alpha Centauri system.

Although astronomers like to talk about things in space happening very slowly, the final deaths and births of stars may occur quite suddenly. For example, a brand-new star suddenly lit up in what is now called McNeil’s Nebula in January 2004. It had probably taken 50 million years for the dust to collapse and condense sufficiently to trigger fusion. Once fusion is triggered, the star stops collapsing because the energy flowing outward keeps the mass in a steady state.

Where does the debris that forms suns come from?

After burning for millions (blue stars) to billions (yellow stars) to tens of billions (red stars) of years, the star eventually runs out of fuel to support fusion, and the mass starts collapsing inward again, forming a hot, dense core and a hugely expanded cooler outer area, namely the star becomes a red giant. What happens next depends on how large the star was in the beginning. Smaller stars collapse into white dwarfs, larger ones explode and leave behind neutron stars, and the largest stars collapse into black holes.

Stars destined to form neutron stars collapse and fusion reactions that form heavy elements like iron take place until the star completely runs out of energy; then, the iron-heavy core collapses on itself and explodes in a massive supernova, which sprays debris in all directions. All of the known elements are created during the process that leads to supernova explosions. The center of what used to be a star collapses into a super dense neutron star and the debris created by the explosion becomes a new star birthing ground.

White Dwarfs vs Black Holes

White dwarfs hang around for a long time and can draw mass away from passing stars, causing them to suddenly ignite in periodic nova explosions. Neutron stars can do this as well. Neutron stars also have strong magnetic fields and they send out beams of radiation. As the star rotates, the beams sweep through space. From Earth, it appears as if periodic pulses of radiation are being sent in our direction; these neutron stars are called pulsars.

Black holes are formed from the largest stars. They go through the red giant and supernova phases, but after the explosion, their core collapses under their massive gravity, and instead of forming a neutron star, they form a black hole. Black holes can only be observed by their gravitational effects on nearby objects, such as neighboring stars, which they consume. During the consumption process, they emit radiation in the form of X and gamma rays, which can be detected.

In summary

New suns are formed from the debris created by old suns dying. It’s a circle of life. The Earth you are standing on was created from a supernova that destroyed an old sun.

The International Space Station (ISS) is so large that it’s visible from Earth without a telescope!  The International Space Station is approximately 250 miles above the surface of the Earth in Low Earth Orbit. Traveling at approximately 17,500 miles per hour, the ISS circles the globe once every ninety minutes. 

Why is the ISS moving across the sky? 

The ISS resides in Low Earth Orbit (LEO). Objects in LEO circle the globe. Objects in Geostationary Orbit (GEO) do not circle the globe and remain stationary above one location.

• Satellites in Low Earth Orbit travel at approximately  4.85 miles per second (7.8 km per second) with an altitude of approximately 160 km to 1000 km above the earth. LEO satellites circle the globe sixteen times each day. The ISS is in LEO.
• Satellites in Geostationary orbit travel approximately 2.26 miles per second (3.8 km per second) with an altitude of approximately 36,000 km above the earth. GEO satellites match the Earth’s rotation speed, appearing “stationary” above the Earth. 

Where do I look? 

The ISS is in a constant state of motion. Atmospheric drag and Earth’s gravity create orbital altitude degradation on the ISS. Changes in the ISS’s altitude modify its trajectory. In theory, the exact orbit path will repeat every three days. 

A good way to determine when the ISS will be traveling near you is to use NASA Spot the Station website. Entry your city, and the website generates a list of upcoming passes near your location. Don’t worry if your exact city isn’t listed. Pick a city that’s close to you. 

Date	Visible	Max Height*	Appears	Disappears
Today, 5:30 AM	5 min	23°	10° above S	10° above ENE
Today, 4:44 PM	2 min	11°	10° above SE	10° above ESE
Tomorrow, 6:18 AM	6 min	29°	10° above WSW	10° above NNE

Here’s an example of a flyby chart from the NASA Spot the Station website based on your current location. 

Which direction should I look?

Take a few moments to orient yourself outdoors. Which direction is N, S, E, W?  

Old School: 

1. Use a compass and orient yourself in the proper direction
2. Use your hands to determine approximate viewing height
   1. Make a fist, knuckles rolled forward, and raise it to eye height
   2. The approximate distance from your thumb to your pinky finger is 10°
   3. Make the “hang loose” or “aloha” symbol with your hand. It’s 25° from your pinky to your thumb.
   4. Pay close attention to the ISS Max Height above the horizon. Landscapes or buildings can easily (easily) cover up to 15-20° of the horizon. 

New School: 

1. Use your favorite cell phone app to orient yourself (N,S,E,W) 
2. Use the app to find the ISS
3. (-) cell phone brightness

There it is!

Now that you’re oriented and know where to look, it’s time to locate the ISS!  Be patient and relax.  Soon enough, you’ll see satellites, even if they’re not the ISS.

When viewing conditions are “correct,” it’s possible to see a string of satellites traversing the nighttime sky lined up in a row.   This unusual sight is known as a Satellite Train.

The number of Low Earth Orbit (LEO) satellites launched is growing each year. The increased number of satellites in orbit has a direct impact on how we view our nighttime skies. Starlink has approximately 3,800 satellites circling the Earth.

Where are the satellites now?

Heavens-Above and Constellation Starlink have fantastic interactive 3D models. The sheer volume of Starlink Satellites is stunning. Select Live Map and locate the satellite train that’s closest to you on Findstarlink, 

Geostationary and Low Earth Orbiting Satellites

• Geostationary (GEO) Satellites are 36,000 km above the Earth.
  • Slow upload/download times.  (High latency.)
• LEO satellites are approximately 160 km to 1000 km above the Earth.
  • Fast upload/download times. (Low latency.)

What’s a Starlink Satellite?

A Starlink Satellite transmits internet signals from a satellite to a ground transceiver. The ground transceiver sends a signal to a router. The end user connects to the internet through the router. 

LEO satellites are constantly “on the move” as they circle the Earth.  This includes crossing over the oceans that cover 71% of the globe.

The best way to ensure global coverage is to place additional satellites into orbit. Each Starlink launch adds approximately 50-60 Starlink Satellites. Starlink is planning on weekly launches.

Who needs it?

Starlink plans to provide high-speed internet access to communities with poor internet service.  Poor service may be due to geographic location or lack of infrastructure.

How Many?

Starlink is the first company to place satellites, in bulk (3,271), into LEO. Starlink currently has FCC approval for 12,000 satellites. Starlink’s projected build-out is closer to 42,000 satellites. A baseline expectation is 100,000 satellites in LEO, (all companies/nations combined) by 2030.

What’s a Starlink Satellite train?

Starlink satellites begin orbit at the approximate height of 350 km and move to an altitude of 550 km. They travel “in a row” as they orbit the Earth. The satellites are visible to the naked eye when they’re at a lower elevation.

A Starlink Satellite train is a row of Satellites traveling across the sky “in a row” or a “string of pearls.”

Astronomers express concern

Astronomers worry that the satellite trains will impact scientific research.  Papers are being published highlighting the satellite train’s negative impact on astronomy.

Astronomers are reflecting on the Kessler syndrome as a real possibility: A satellite breaks or shatters into smaller pieces. A second satellite files through the debris field. The second satellite breaks or shatters into smaller pieces.  Snowball effect.

Moving forward

Faster internet connections may be the beginning of an economic equalizer for less developed regions. Increasing the number of satellites in low earth orbit may cause considerable scientific angst. What’s the right answer?  

The science of astronomy has defined a galaxy as a system of stars, planets, dust, and other materials that revolve around a common center of mass. A galaxy can be very large and include billions of stars.

Many galaxies have names. The names are often based on the constellation or the location of the star. Some galaxies have more interesting names than others. Most of these are named by astronomers who discovered them.

Spiral Galaxies

Spiral galaxies are the brightest galaxies that are far away. They are made up of stars and planets that are rotating in the opposite direction to shape the galaxy. There are lots of colors in the material in these galaxies. Another type of galaxy is an elliptical galaxy. These galaxies are shaped like grains of rice.

Galaxies are grouped together based on their gravitational attraction. Many galaxies are also grouped into clusters. One of these groups is the Local Group of 54 galaxies. This group includes our own Milky Way galaxy. It consists of hundreds of billions of stars.

Types of Galaxies

Most modern catalogs of galaxies contain thousands of objects. The New General Catalog of Principal Galaxies, for example, has over 73,000 objects in it. When a new catalog is published, most of the objects have catalog designations. For instance, the Whirlpool Galaxy is a Messier object. Another example is the Pinwheel Galaxy, which is located in the Coma Benerices constellation.

Galaxies can be classified into three basic types. These are barred spiral, barred elliptical, and elliptical. While most are categorized by their size, some are still grouped by their shape. In general, a galaxy is a collection of planets and stars, but can also be a system of nebulae and dust.

The names of galaxies can vary, depending on how the catalog is compiled. Some galaxies are not included because they do not show up as separate objects in the sky. Others are only part of larger galaxy clusters. An example is the Sagittarius Dwarf Spheroidal Galaxy, which is not listed because it is not seen as a separate galaxy.

There are also a number of unusually shaped galaxies. These include galaxies in the process of colliding, and galaxies with active nuclei. These objects are thought to be in a transitory phase of galactic development.

Where Do Galaxies Get Their Names?

Several ancient cultures named ten thousand stars. However, there are only a few thousand that are bright enough for human observation with the naked eye. Using the names of stars and constellations is a great way to learn about outer space and the universe. You can also visit a planetarium to see displays of deep-space features.

Although it can be challenging to identify certain galaxies, the International Astronomical Union has produced several official catalogs. The New General Catalog of Nebulae and Star Clusters is the most widely used catalog. Other popular catalogs are the Atlas of Peculiar Galaxies, the Extragalactic Catalog, and the Markarian Catalog.

It’s always interesting to hypothesize about where various moons come from. In some cases, the creation of a moon is easy to determine, but with the origin of Mars’ moons, that is not the case. With some planets, it’s pretty obvious that a moon was formed due to an impact, such is believed to be the case with Earth’s moon, but what about its next-door neighbor, Mars? The origin of Mars’ moons don’t appear to come from this type of source, and there’s one main reason that astronomers theorize this: the composition of the moons.

What Are Mars’ Moons Made out of?

The composition of Mars’ moons put them in a category that astronomers call “C-Type asteroids”. These are the most common type of asteroids in the Solar System, making up for over 80% of all asteroids, especially those in the outer part of the asteroid belt. The “C” in the name stands for carbon and refers to the predominant material found throughout the moons surface.

Astronomers are far more certain about the material composition of the larger, innermost moon. This is for a few reasons, and not just because there is more surface area to explore. Stickney, the large crater, allows for the investigation of the fine dust and boulders that the impact left behind, which allows for the scientists to further conclude that this moon is very likely made up of a carbonaceous material.

It is a little more difficult to ascertain the material of the smaller, outermost moon. Due to its size, its gravitational pull is much, much weaker. This presents a problem. Typically, when small meteors hit the surface, surface material is thrown up and it returns down, creating the dusty and rocky features that make up the barren moons that you are used to seeing.

It is believed that this small moon’s gravity is so low that the ejected material simply doesn’t come back down, leaving its surface much smoother, but this makes it more troublesome to be certain that it is also the same carbonaceous material, though scientists are pretty sure that it is, based on the similarities to the other moon.

Discovering the Origin of Mars’ Moons

The truth is that the origins of these moons still remain a debate among astronomers to this day. Many believe that, in some way, they originated in the nearby asteroid belt. The question is when they came to Mars’ side. Some astronomers believe that these moons came to the planet after it had formed and established its gravitational pull, dragging the asteroids out of the belt on their own. Others believe that the asteroids had already drifted out around the time that Mars was beginning to form and came along for the ride with Mars’ formation. The true origins still remain controversial.