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Saturn is a gas giant planet, and the sixth planet from the Sun in our solar system. It is the second-largest planet in our solar system.

The radius is about nine times that of Earth, so it’s volume is about 95 times larger than Earth.

It has only one-eighth the average density of Earth.

Named after the Roman god of wealth and agriculture.

Its astronomical symbol (♄) represents Saturn’s sickle.

Saturn's satellites and ring structures

Planets: Gas giants and Ice giants

3D app – Saturn And It’s Major Moons, from 3dwarehouse

Possible habitat for life on Enceladus, a moon of Saturn

How Saturn and the other planets got their names


The Drake Equation

“The Drake Equation is a way to estimate the number of communicating advanced civilizations (N) inhabiting the Galaxy. It is named after Frank Drake who first summarized the things we need to know to answer the question, “how many of them are out there?” The equation breaks this big unknown, complex question into several smaller (hopefully manageable) parts. Once you know how to deal with each of the pieces, you can put them together to come up with a decent guess.”

– Nick Strobel, Astronomy Notes

drake equation SETI

Image from universetoday.com, drake-equation


Luciano Ingenito Drake Equation SETI

Luciano Ingenito | CC by-nc-nd 4.0


The Drake Equation interactive PBS NOVA



SETI notes

The search for extraterrestrial intelligence (SETI) is a collective term for any scientific searches for intelligent extraterrestrial life. It is primarily done by monitoring radio signals for signs of transmissions from civilizations on other planets.

What are radio waves?

Radio waves are just a part of the EM (electromagnetic) spectrum.

Gamma rays Spectrum Properties NASA

That sounds dandy, except, what exactly is the “electromagnetic spectrum”?

All parts of the EM spectrum – radio, visible light, etc. – are oscillating electric and magnetic fields. To learn the details, see Light is an electromagnetic field.


How are radio waves different from other parts of the EM spectrum?

They’re made of the same thing, behaving in exactly the same way. Only difference is that radio waves are hundreds of meters to thousands of meters long. Other parts of the spectrum have shorter waves.

What creates radio waves?

With a radio receiver we can hear radio waves coming from all around us. They are naturally produced, and comes from all over the Earth, and outer space. Radio waves are naturally created by:

* Wind whipping over a surface, creating static electricity

* Lightning

* atoms trapped in the magnetic fields around the Earth, and around all other planets as well.

* The Sun (puts out all frequencies of EM radiation!)

* All stars

* Ionized interstellar gas surrounding bright, hot stars

* Supernovas

* There are even more complex radio waves naturally generated, you can read this paper: Natural and man-made terrestrial electromagnetic noise

By the late 1800’s humans had learned not only how to receive radio waves, but how to generate them. Today we artificially create radio waves for all sorts of purposes, including

  • Traditional, over-the-air, radio stations (AM and FM radio)

  • Traditional, old-fashioned, TV (television)

  • Wi-Fi

  • Bluetooth

  • Cellphone communication (cell towers and the phones)

Cornell.edu: Observational-astronomy. SETI and extraterrestrial life

Kaiserscience – All about the electromagnetic spectrum

What is a radio telescope?

The technology of how we detect radio waves.


radio telescope

Image from website of James Schombert, Dept of Physics, Univ. Oregon

How does an antenna pick up radio waves?

“If we place a conducting material on the path of such a wave, the passing wave will create an oscillating electric field inside the material; and that field will accelerate charges back and forth through the conductor.”

radio antenna dipole oscillating electric field



History of SETI

This section has been adapted from “Search for extraterrestrial intelligence.” Wikipedia, The Free Encyclopedia. 4 Mar. 2019

There have been many earlier searches for extraterrestrial intelligence within the Solar System. In 1896, Nikola Tesla suggested that an extreme version of his wireless electrical transmission system could be used to contact beings on Mars. He conducted an experiment at his Colorado Springs experimental station.

In the early 1900s, Guglielmo Marconi, Lord Kelvin and David Peck Todd also stated their belief that radio could be used to contact Martians, with Marconi stating that his stations had also picked up potential Martian signals.

On August 21–23, 1924, Mars entered an opposition closer to Earth than at any time in the century before or the next 80 years. In the United States, a “National Radio Silence Day” was promoted during a 36-hour period from August 21–23, with all radios quiet for five minutes on the hour, every hour.

At the United States Naval Observatory, scientists used a radio receiver, miles above the ground in a dirigible, to listen for any potential radio messages from Mars.

A 1959 paper by Philip Morrison and Giuseppe Cocconi first pointed out the possibility of searching the microwave spectrum, and proposed frequencies and a set of initial targets.

In 1960, Cornell University astronomer Frank Drake performed the first modern SETI experiment, named “Project Ozma”, after the Queen of Oz in L. Frank Baum’s fantasy books. Drake used a radio telescope at Green Bank, West Virginia, to examine the stars Tau Ceti and Epsilon Eridani.

Soviet scientists took a strong interest in SETI during the 1960s and performed a number of searches. Soviet astronomer Iosif Shklovsky wrote the pioneering book in the field, Universe, Life, Intelligence (1962), which was expanded upon by American astronomer Carl Sagan as the best-selling book Intelligent Life in the Universe (1966).

In the March 1955 issue of Scientific American, John D. Kraus described an idea to scan the cosmos for natural radio signals using a radio telescope. Ohio State University soon created a SETI program.

In 1971, NASA funded a SETI study that involved Drake, Bernard M. Oliver of Hewlett-Packard Corporation, and others. The resulting report proposed the construction of an Earth-based radio telescope array with 1,500 dishes known as “Project Cyclops”. It was not built, but the report formed the basis of much SETI work that followed.

Why don’t any organisms detect radio waves?

(Honors Biology topic)

Whyevolutionistrue.wordpress.com : Why-don’t-any-organisms-detect-radio-waves?

How difficult will this be?

It is very difficult to pick up Earth’s radio waves from another solar system. As such, we can imagine that it would  very difficult to pick up radio waves here, from some other solar system. That’s why we aren’t really looking for random radio waves that happen to escape out into space. Rather, the current projects are looking for much more powerful signals, that we hope would be sent out on purpose.


“That’s a rather extraordinary claim, so I spoke to SETI expert and scifi novelist David Brin about it — and he’s not convinced detection is this easy. He told me that, even if an ETI had a one square kilometer array, they would have to point it a at Earth for the duration of an entire year. “Because it would take that long,” he told io9. “But why stare if you don’t already have a reason to suspect?”

Like SETI Institute’s Seth Shostak, Brin believes that Earth is not detectable beyond five light years. “With one exception: Narrow-focused, coherent (laser-like) planetary radars that are aimed to briefly scan the surfaces of asteroids and moons,” he says, “And not to be confused with military radars that disperse.””

How can we differentiate between natural or artificial (intelligent) signals?

Consider listening to the sound of radio static. Compare that to the sound of a song, or a person giving a speech. Both are sounds – how are they similar? How are they different?

Come up with ideas on how we could differentiate between natural or artificial (intelligent) signals.

“Humanity has received some odd signals in the past. We’ve also sent out some signals ourselves. How could we determine that a signal we’d received was artificial in origin? Or of course inversely, how could an extraterrestrial civilization determine a signal we had sent out was was artificial?”

Space.stackexchange.com – What-evidence-would-be-needed-to-determine-a-signal-was-artificial-in-origin?

Listening for Extraterrestrial Blah Blah: At the cosmic dinner party, intelligence is the loudest thing in the room. By Laurance R. Doyle, Illustrations by Tianhua Mao

Listening for Extraterrestrial Blah Blah

The Water hole: What radio frequencies should we listen to?


Hailing Frequencies Open, Captain! What is the “water hole”?


Misconceptions about listening with radio telescopes

Radio signals diminish in strength very rapidly with distance – they decrease according to the inverse square law. What does that mean Consider cooking spray. Oil is sprayed through an opening. In this image, the cooking spray hits a piece of toast and deposits an even layer of butter, 1 mm thick.

Hewitt Inverse Square Law Butter gun

Hewitt textbook

When the butter gets twice as far, it becomes only 1/4 as this.
If it travels 3 times as far, it will spread out to cover 3 x 3,
or 9, pieces of toast.
So now the butter will only be 1/9th as thick.
(1/9 is the inverse square of 3)
This pattern is called an inverse-square law.
The same is true for a can of spray paint: as the paint travels further, it covers a wider area, so the paint per area is inversely less thick.

Hewit inverse square law spray paint

Hewitt Conceptual Physics worksheets

The same pattern of spreading out and weakening, the inverse square laws, is true for radio waves.

Inverse Square Law GIF

Animations of the inverse-square law – animated clip: Inverse-square law for light

Okay – so by the time that radio signals reach even the next solar system they would be unbelievably weak. The radio signals would be even millions of times weaker by the time they travelled across even 1% of the galaxy. Our radio telescopes could never pick up such radio signals.

So if that’s the case, what then are SETI researchers listening for?We are looking for a civilization that wants to be known, one that has deliberately built a high power radio beacon, aimed in one direction at a time. A tightly beamed signal would be millions of times stronger – if by chance we happen to be in its path.

Do SETI researchers believe that someone out there is deliberately sending a signal to us here on Earth specifically? No. However, we know that there are billions of stars, and tens of billions of planets. Many of these planets might support life. Therefore, at any given time there could be many thousands of other worlds with intelligent life

The hope is that some of them would want to communicate, sending a tight, beamed radio signal out into space. If so, then one day we might intercept such a communication.

Article: Is there anybody out there? Jason Davis, October 25, 2017, The Planetary Society

Planetary.org – Is there anybody out there?

Goldilocks Zone/Circumstellar habitable zone

This section from evolution.berkeley.edu, A Place for Life: A special astronomy exhibit of Understanding Evolution

From the known properties of stars and of the chemistry of water, astronomers can define “habitable zones” around stars where liquid water (and hence life) could exist on the surface of planets.

Too close to the star, and water will boil; too far, and it will freeze. This so-called Goldilocks zone, where the temperature is just right, depends on both the distance from the star and the characteristics of the star itself.

The habitable zone around luminous giant stars is further from the star than the habitable zone around faint dwarfs.

Of course, as noted previously, life may also exist outside these zones, for example in subsurface oceans on icy moons heated from the moon’s interior.

We know that there are around 200 billion stars in our Galaxy. Recent research has revealed that most of them have planets, and that tens of billions of these planets are likely similar in size to Earth, made of rock, and orbit in their stars’ habitable zones.

The question that remains to be answered is what fraction of those potentially habitable worlds host life.


Image converted using ifftoany

from the NASA Kepler Mission



Habitable Zones of Different Stars. NASA/Kepler Mission/Dana Berry.


Habitable zones for binary star systems

What about planets in a solar system with two stars?

Most stars in the Galaxy have at least one stellar companion—binary or multiple star systems. Stars like our Sun with no stellar companion are in the minority.

It would probably be difficult for there to be stable, only slightly elliptical planet orbits in a binary or multiple star system.

Complex life (multi-cellular) will need to have a stable temperature regime to form so the planet orbit cannot be too eccentric. Simple life like bacteria might be able to withstand large temperature changes on a planet with a significantly elliptical orbit but complex life is the much more interesting case.

Suitable binary stars would be those systems where either:

(a) the binary stars orbit very close to each other with the planet(s) orbiting both of them at a large distance (called a “circumbinary planet”)

or (b) the binary stars orbit very far from each other so the planet(s) could reside in stable orbits near each of the stars—the one star’s gravity acting on a planet would be much stronger than that of the other star.

Goldilocks habitable zone binary star

Image by Nick Strobel

image from https://www.astronomynotes.com/lifezone/s2.htm

A cool article on this subject:  I Built a Stable Planetary System with 416 Planets in the Habitable Zone


Strong magnetic fields may be necessary

Earth has a strong magnetic field. Turns out that this might be necessary on a planet if complex life is to evolve.

magnetic_field Earth


Why does Earth have such a strong magnetic field? Earth’s core is still hot and molten. Metal still moves inside it, and moving metal has moving free electrons. Electrons moving around – by definition – are an electrical current. And it turns out that electrical currents create their own magnetic field!

Electric current creates magnetic field

Image from S-cool revision. GCSE » Physics » Magnetism and Electromagnetism

Inside the earth

This field protects the Earth’s atmosphere from some of the Sun’s radiation.

Without such a field most of a planet’s atmosphere is likely to be blown away into space, as happened to Mars.

Mars now has very little atmosphere, and its surface is constantly irradiated by solar radiation.

Mars Earth biosphere due to magnetic field

The Drake Equation

An equation named after Frank Drake, who first summarized the things we need to know to answer the question, “how many possible extraterrestrial civilizations are out there?” The equation breaks this complex question into several smaller (hopefully manageable) parts.

The Drake Equation

Learning Standards

(for the entire SETI unit)

Common Core, English Language Arts Standards » Science & Technical Subjects

CCSS.ELA-LITERACY.RST.9-10.1 – Cite specific textual evidence to support analysis of science and technical texts, attending to the precise details of explanations or descriptions.

CCSS.ELA-LITERACY.RST.9-10.2 – Determine the central ideas or conclusions of a text; trace the text’s explanation or depiction of a complex process, phenomenon, or concept; provide an accurate summary of the text.

CCSS.ELA-LITERACY.RST.9-10.4 – Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context.

CCSS.ELA-LITERACY.RST.9-10.5 –  Analyze the structure of the relationships among concepts in a text, including relationships among key terms (e.g., force, friction, reaction force, energy).

CCSS.ELA-LITERACY.RST.9-10.6 – Analyze the author’s purpose in providing an explanation, describing a procedure, or discussing an experiment in a text, defining the question the author seeks to address.

2016 Massachusetts Science and Technology/Engineering Curriculum Framework

HS-PS2-5. Provide evidence that an electric current can produce a magnetic field and that a changing magnetic field can produce an electric current.

6.MS-PS4-1. Use diagrams of a simple wave to explain that (a) a wave has a repeating pattern with a specific amplitude, frequency, and wavelength, and (b) the amplitude of a wave is related to the energy of the wave.

HS-PS4-1. Use mathematical representations to support a claim regarding relationships among the frequency, wavelength, and speed of waves traveling within various media. Recognize that electromagnetic waves can travel through empty space (without a medium) as compared to mechanical waves that require a medium.

HS-PS4-5. Communicate technical information about how some technological devices use the principles of wave behavior and wave interactions with matter to transmit and capture information and energy.

Next Generation Science Standards: Science & Engineering Practices
● Ask questions that arise from careful observation of phenomena, or unexpected results, to clarify and/or seek additional information.
● Ask questions that arise from examining models or a theory, to clarify and/or seek additional information and relationships.
● Ask questions to determine relationships, including quantitative relationships, between independent and dependent variables.
● Evaluate a question to determine if it is testable and relevant.
● Ask and/or evaluate questions that challenge the premise(s) of an argument, the interpretation of a data set, or the suitability of the design

Common Core Math Standards (Inverse-square law)

CCSS.Math.Content.7.RP.A.2a ( Grade 7 ): Decide whether two quantities are in a proportional relationship, e.g., by testing for equivalent ratios in a table or graphing on a coordinate plane and observing whether the graph is a straight line through the origin.
CCSS.Math.Content.7.RP.A.2c ( Grade 7 ): Represent proportional relationships by equations.

The Physics of Interstellar Travel

Why should humanity eventually colonize the stars?

“Ask ten different scientists about the environment, population control, genetics and you’ll get ten different answers, but there’s one thing every scientist on the planet agrees on. Whether it happens in a hundred years or a thousand years or a million years, eventually our Sun will grow cold and go out. When that happens, it won’t just take us. It’ll take Marilyn Monroe and Lao-Tzu, Einstein, Morobuto, Buddy Holly, Aristophanes .. and all of this .. all of this was for nothing unless we go to the stars.”

– Writer J. Michael Straczynski, from a character’s speech (Commander Sinclair) in Babylon 5, season 1, “Infection”

This a resource for a future lesson on physically possible ways of interstellar travel.


Lawrence H. Ford and Thomas A. Roman. Sci Am article.


Ways that currently only exist in science fiction:

In Star Trek, spaceships have a warp drive.

In Star Wars, spaceships have a hyperdrive, to send a ship through hyperspace.

Some sci-fi novels postulate a technology called a jump drive – This allows a starship to be instantaneously teleported between two points.

In Stargate the characters use a traversable wormhole – the idea is based on the Einstein–Rosen bridge.

Current space travel technology

Rockets powered by chemical reactions

New Horizons mission has rocket thrusters fueled with hydrazine. Chemical reaction powered rockets are good for manned or unmanned missions within our solar system.

Ionic propulsion

This is the slowest method, but also the most efficient, as it needs much less fuel. Uses engines such as the Hall-effect thruster (HET). Used in European Space Agency’s (ESA) SMART-1 mission. Good for unmanned missions within our solar system.


Matt Williams writes

Nuclear Thermal and Nuclear Electric Propulsion (NTP/NEP)

Another possibility for interstellar space flight is to use spacecraft equipped with nuclear engines, a concept which NASA has been exploring for decades. In a Nuclear Thermal Propulsion (NTP) rocket, uranium or deuterium reactions are used to heat liquid hydrogen inside a reactor, turning it into ionized hydrogen gas (plasma), which is then channeled through a rocket nozzle to generate thrust.

A Nuclear Electric Propulsion (NEP) rocket involves the same basic reactor converting its heat and energy into electrical energy, which would then power an electrical engine. In both cases, the rocket would rely on nuclear fission or fusion to generates propulsion rather than chemical propellants, which has been the mainstay of NASA and all other space agencies to date.

Although no nuclear-thermal engines have ever flown, several design concepts have been built and tested over the past few decades, and numerous concepts have been proposed. These have ranged from the traditional solid-core design – such as the Nuclear Engine for Rocket Vehicle Application (NERVA) – to more advanced and efficient concepts that rely on either a liquid or a gas core.

However, despite these advantages in fuel-efficiency and specific impulse, the most sophisticated NTP concept has a maximum specific impulse of 5000 seconds (50 kN·s/kg). Using nuclear engines driven by fission or fusion, NASA scientists estimate it would could take a spaceship only 90 days to get to Mars when the planet was at “opposition” – i.e. as close as 55,000,000 km from Earth.

But adjusted for a one-way journey to Proxima Centauri, a nuclear rocket would still take centuries to accelerate to the point where it was flying a fraction of the speed of light. It would then require several decades of travel time, followed by many more centuries of deceleration before reaching it destination. All told, were still talking about 1000 years before it reaches its destination. Good for interplanetary missions, not so good for interstellar ones.

Realistic extensions of current technology

Fusion Rockets

[One could use] thermonuclear reactions to generate thrust. For this concept, energy is created when pellets of a deuterium/helium-3 mix are ignited in a reaction chamber by inertial confinement using electron beams (similar to what is done at the National Ignition Facility in California). This fusion reactor would detonate 250 pellets per second to create high-energy plasma, which would then be directed by a magnetic nozzle to create thrust.

Like a rocket that relies on a nuclear reactor, this concept offers advantages as far as fuel efficiency and specific impulse are concerned. Exhaust velocities of up to 10,600 km/s are estimated, which is far beyond the speed of conventional rockets. What’s more, the technology has been studied extensively over the past few decades, and many proposals have been made.

For example, between 1973 and 1978, the British Interplanetary Society conducted feasibility study known as Project Daedalus. Relying on current knowledge of fusion technology and existing methods, the study called for the creation of a two-stage unmanned scientific probe making a trip to Barnard’s Star (5.9 light years from Earth) in a single lifetime.

The first stage, the larger of the two, would operate for 2.05 years and accelerate the spacecraft to 7.1% the speed of light (o.071 c). This stage would then be jettisoned, at which point, the second stage would ignite its engine and accelerate the spacecraft up to about 12% of light speed (0.12 c) over the course of 1.8 years. The second-stage engine would then be shut down and the ship would enter into a 46-year cruise period.

Project Daedalus spacecraft, by Adrian Mann

According to the Project’s estimates, the mission would take 50 years to reach Barnard’s Star. Adjusted for Proxima Centauri, the same craft could make the trip in 36 years. But of course, the project also identified numerous stumbling blocks that made it unfeasible using then-current technology – most of which are still unresolved.

For instance, there is the fact that helium-3 is scare on Earth, which means it would have to be mined elsewhere (most likely on the Moon). Second, the reaction that drives the spacecraft requires that the energy released vastly exceed the energy used to trigger the reaction. And while experiments here on Earth have surpassed the “break-even goal”, we are still a long way away from the kinds of energy needed to power an interstellar spaceship.

Speculative technologies for space travel

Fusion Ramjet

Also known as the Bussard Ramjet, this theoretical form of propulsion was first proposed by physicist Robert W. Bussard in 1960. Basically, it is an improvement over the standard nuclear fusion rocket, which uses magnetic fields to compress hydrogen fuel to the point that fusion occurs. But in the Ramjet’s case, an enormous electromagnetic funnel “scoops” hydrogen from the interstellar medium and dumps it into the reactor as fuel.

As the ship picks up speed, the reactive mass is forced into a progressively constricted magnetic field, compressing it until thermonuclear fusion occurs. The magnetic field then directs the energy as rocket exhaust through an engine nozzle, thereby accelerating the vessel. Without any fuel tanks to weigh it down, a fusion ramjet could achieve speeds approaching 4% of the speed of light and travel anywhere in the galaxy.

However, the potential drawbacks of this design are numerous. For instance, there is the problem of drag. The ship relies on increased speed to accumulate fuel, but as it collides with more and more interstellar hydrogen, it may also lose speed – especially in denser regions of the galaxy. Second, deuterium and tritium (used in fusion reactors here on Earth) are rare in space, whereas fusing regular hydrogen (which is plentiful in space) is beyond our current methods.

Antimatter-Matter annihilation powered rocket

Fans of science fiction are sure to have heard of antimatter. But in case you haven’t, antimatter is essentially material composed of antiparticles, which have the same mass but opposite charge as regular particles. An antimatter engine, meanwhile, is a form of propulsion that uses interactions between matter and antimatter to generate power, or to create thrust.

In short, an antimatter engine involves particles of hydrogen and antihydrogen being slammed together. This reaction unleashes as much as energy as a thermonuclear bomb, along with a shower of subatomic particles called pions and muons. These particles, which would travel at one-third the speed of light, are then be channeled by a magnetic nozzle to generate thrust.

The advantage to this class of rocket is that a large fraction of the rest mass of a matter/antimatter mixture may be converted to energy, allowing antimatter rockets to have a far higher energy density and specific impulse than any other proposed class of rocket. What’s more, controlling this kind of reaction could conceivably push a rocket up to half the speed of light.

Pound for pound, this class of ship would be the fastest and most fuel-efficient ever conceived. Whereas conventional rockets require tons of chemical fuel to propel a spaceship to its destination, an antimatter engine could do the same job with just a few milligrams of fuel. In fact, the mutual annihilation of a half pound of hydrogen and antihydrogen particles would unleash more energy than a 10-megaton hydrogen bomb.

It is for this exact reason that NASA’s Institute for Advanced Concepts (NIAC) has investigated the technology as a possible means for future Mars missions. Unfortunately, when contemplating missions to nearby star systems, the amount if fuel needs to make the trip is multiplied exponentially, and the cost involved in producing it would be astronomical (no pun!).

How Long Would It Take To Travel To The Nearest Star?

NASA PDF PowerPoint: Realistic Interstellar Travel

Ask Ethan: Is Interstellar Travel Possible? Forbes


What technologies would we need to develop?

Chemical rocket spaceships

Solar sail spaceships

Nuclear fission powered spaceships

Nuclear fusion powered spaceships

Matter-Anti-matter spaceships

How long would it take a spaceship to get from one star to another?

To get to the center of our galaxy?


The Big Problem With Interstellar Travel, YouTube, RealLifeLore

Interstellar Travel: Approaching Light Speed. Jimiticus

Interstellar Travel – Speculative Documentary HD

Warp drive

Many people are familiar with warp drive as a form of FTL (Faster Than Light travel.) Its most popular use is in the science-fiction series Star Trek. According to the laws of physics could this potentially be possible?

Possibility of a real life warp drive, The Alcubierre drive. (KaiserScience)

Warp Drive Research Key to Interstellar Travel, Scientific American


External resources and articles

Physics of interstellar travel Michio Kaku

Space.com articles on interstellar travel

Pros and Cons of Various Methods of Interstellar Travel, Universe Today

Space.StackExchange – [interstellar-travel]

Concepts for Deep Space Travel: From Warp Drives and Hibernation to World Ships and Cryogenics“, Current Trends in Biomedical Engineering and Biosciences


Learning Standards

Massachusetts Curriculum Frameworks Science and Technology/Engineering (2016) 

6.MS-ESS1-5(MA). Use graphical displays to illustrate that Earth and its solar system are one of many in the Milky Way galaxy, which is one of billions of galaxies in the universe.

A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (2012)

By the end of grade 8. Patterns of the apparent motion of the sun, the moon, and stars in the sky can be observed, described, predicted, and explained with models. The universe began with a period of extreme and rapid expansion known as the Big Bang. Earth and its solar system are part of the Milky Way galaxy, which is one of many galaxies in the universe.

Next Generation Science Standards

4-PS3 Energy, Disciplinary Core Ideas, ETS1.A: Defining Engineering Problems

 Possible solutions to a problem are limited by available materials and resources (constraints). The success of a designed solution is determined by considering the desired features of a solution (criteria). Different proposals for solutions can be compared on the basis of how well each one meets the specified criteria for success or how well each takes the constraints into account. (secondary to 4-PS3-4)

Common Core State Standards Connections: ELA/Literacy

RST.6-8.8 Distinguish among facts, reasoned judgment based on research findings, and speculation in a text. (MS-LS2-5)

RI.8.8 Trace and evaluate the argument and specific claims in a text, assessing whether the reasoning is sound and the evidence is relevant and sufficient to support the claims. (MS-LS-4),(MS-LS2-5)

WHST.6-8.2 Write informative/explanatory texts to examine a topic and convey ideas, concepts, and information through the selection, organization, and analysis of relevant content. (MS-LS2-2)


Detecting Planet X

Social media and internet searches show a plethora of articles on “Planet X”, a vaguely worded term for some supposedly mysterious planet of apparently great importance.There are also conspiracy theories about the government or NASA supposedly hiding “Planet X” for some nefarious reason.

In science, we generally never use this phrase. When a scientist does say “Planet X” he/she merely means “any undetected planet in our solar system”.

Planets beyond Pluto

Scientists never quite said “Pluto isn’t a planet anymore.” That’s a misleading statement which muddies the waters. Here’s what really is going on.

Old view

Solar system is made of one star, several planets, comets, meteors, and gas & dust particles.

More recent, yet now outdated view

Solar system is made of one star, several planets, comets, meteors, and gas & dust particles.
The planets are either terrestrial (“Earth like”) or gas giants.

New view

Solar system is made of one star, several planets, comets, meteors, and gas & dust particles.
The planets are now in categories:
terrestrial, gas giants, ice giants, or dwarf planets.

So all that really happened is that Pluto was moved from one general group, into a more specific group (dwarf planets.)

Here are some of the planets beyond Pluto, in our own solar system, already discovered. For size comparison they are shown as if they are near each other.

Ceres, Charon, Eris, Dysnomia, Pluto, Haumea, Makemake,


This picture shows the sizes of the original three dwarf planets (Eris, Ceres, and Pluto) as compared to Earth. It also shows Pluto’s large moon Charon (and its two small moons Nix and Hydra) and Eris’s moon Dysnomia to scale. The image also shows Earth’s Moon (Luna) and the planet Mars for comparison. None of the distances between objects in this image are to scale. Images courtesy of NASA, ESA, JPL, and A. Feild (STScI).

also see

Dwarf Planets Pluto Makemake Haumea Eris

Credit: Konkoly Observatory/András Pál, Hungarian Astronomical Association/Iván Éder, NASA/JHUAPL/SwRI

Why is it difficult to find new worlds?

Out there, space gets dark alarmingly fast. Planets twice as far away look 16 times dimmer: The intensity of the sunlight weakens by a factor of four going out and then four times again coming back.

At an orbital distance of 600 astronomical units (an AU is the distance between Earth and the sun), Planet Nine would be 160,000 times dimmer than Neptune is at 30 AU.

At 1,000 AU, it would appear more than 1 million times weaker.

“There’s really a brick wall, basically, at 1,000 AU,” said Kevin Luhman, an astronomer at Pennsylvania State University.” That’s partly why laying eyes on the planet has proven so tough.

Why Can’t We Find Planet Nine? Quanta Magazine

Possible large planet orbiting beyond Pluto


Planet X detection new planets

Related articles

Evidence that we’re seeing effects of a 10th planet

Looking for Planet Nine, Astronomers Gaze into the Abyss

How Astronomers Are Going to Find Planet Nine

XKCD Possible Undiscovered Planets Comic: Funny yet scientifically accurate

Swarm of asteroids instead of another plant

No Need for Planet Nine? Small Objects’ Gravity Could Explain Weird Orbits

A New Study Could Explain Away Some Evidence for Planet Nine

Goodbye, Planet Nine! New and better data disfavors the existence of a giant world beyond Neptune.

General resources



Science Bulletins: The Hunt for Planet X. American Museum for Natural History.

Astronomers find evidence of a ninth planet in the solar system – Caltech, Robert Hunt, Reuters



Learning Standards

Next Generation Science Standards
Connections to Nature of Science: Science Models, Laws, Mechanisms, and Theories Explain Natural Phenomena.
A scientific theory is a substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment, and the science community validates each theory before it is accepted. If new evidence is discovered that the theory does not accommodate, then the theory is generally modified in light of this new evidence. (HS-ESS1-2),(HS-ESS1-6)

A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (2012)

Some objects in the solar system can be seen with the naked eye. Planets in the night sky change positions and are not always visible from Earth as they orbit the sun. Stars appear in patterns called constellations, which can be used for navigation and appear to move together across the sky because of Earth’s rotation…. The solar system consists of the sun and a collection of objects, including planets, their moons, and asteroids that are held in orbit around the sun by its gravitational pull on them. This model of the solar system can explain tides, eclipses of the sun and the moon, and the motion of the planets in the sky relative to the stars.


The Expanse is a series of science fiction novels, novellas and stories by James S. A. Corey – the pen name of authors Daniel Abraham and Ty Franck. The first novel, Leviathan Wakes, was nominated for the Hugo Award for Best Novel in 2012. In 2017 the series as a whole was nominated for the ‘Best Series’ Hugo Award.

These novels are the basis of an American science fiction television series developed by Mark Fergus and Hawk Ostby. The series received positive reviews from critics, who highlighted its visuals, character development, and political narrative. It received a Hugo Award for Best Dramatic Presentation as well as a Saturn Award nomination.

  • Wikipedia

James A Corey The Expanse Leviathan Wakes Caliban's War







Related works

  • “The Butcher of Anderson Station” (The Expanse short story) (2011)
  • Gods of Risk (The Expanse novella) (2012)
  • “Drive” (The Expanse short story) (2012)
  • The Churn (The Expanse novella) (2014)
  • The Vital Abyss (The Expanse novella) (2015)
  • Strange Dogs (The Expanse novella) (2017)

Television series


Possible rocket engines

from ATOMIC ROCKETSHIPS OF THE SPACE PATROL or “So You Wanna Build A Rocket?” by Winchell D. Chung Jr..

Here is your handy-dandy cheat-sheet of rocket engines. Use this as a jumping-off point, there is no way I can keep this up-to-date. Google is your friend!

I’ll point out a few of the more useful items on the sheet:

  • Aluminum-Oxygen is feeble, but is great for a lunar base (the raw materials are in the dirt).

  • VASIMR is the current favorite among ion-drive fans. Use this with orbit-to-orbit ships that never land on a planet. It can “shift gears” like an automobile.

  • Solar Moth might be a good emergency back-up engine.

  • Nuclear Thermal Solid Core is better than feeble chemical rockets, but not as much as you’d expect.

  • Nuclear Thermal Vapor Core is what you design along the way while learning how to make a gas core atomic rocket.

  • Nuclear Thermal Gas Core Open-Cycle is a full-blown honest-to-Heinlein atomic rocket, spraying glowing radioactive death in its exhaust.

  • Nuclear Thermal Gas Core Closed-Cycle is an attempt to have the advantages of both nuclear solid core and gas core, but often has the disadvantages of both. It has about half the exhaust velocity of an open-cycle atomic rocket.

  • Orion Nuclear Pulse is a rocket driven by detonating hundreds of nuclear bombs. If you can get past freaking out about the “bomb” part, it actually has many advantages. Don’t miss the Medusa variant.

  • Magneto Inertial Fusion This is the best fusion-power rocket design to date.

  • Zubrin’s Nuclear Salt Water This is the most over-the-top rocket. Imagine a continuously detonating Orion drive. There are many scientist who question how the rocket can possibly survive turning the drive on.


The only human being in existence not in this photo

Michael Collins is the only human being in the history of the world, living or dead, who is not contained in the frame of this picture.

Michael Collins (born October 31, 1930), Major General, USAF, Ret., is an American former astronaut and test pilot. …His first spaceflight was on Gemini 10, in which he and Command Pilot John Young performed two rendezvous with different spacecraft and Collins undertook two EVAs. His second spaceflight was as the Command Module Pilot for Apollo 11 [July 16-24, 1969]. While he stayed in orbit around the Moon, Neil Armstrong and Buzz Aldrin left in the Lunar Module to make the first manned landing on its surface. Collins is one of only 24 people to have flown to the Moon. Michael Collins (Wikipedia)

Michael Collins is the only human NASA astronaut