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We’ve thrown a lot of disasters at Earth over the years: from asteroids and aliens, to the Sun’s death. But hey, the Universe is a dangerous place, and we’re not done yet. Now we’re going to throw a black hole into the mix, and not just any black hole, but a blazar. Black holes are usually found at the center of the galaxy. The Milky Way has a black hole that is four million times the mass of the Sun. But that’s small compared to other black holes out there. How old is the oldest blazar? Why can we see some blazars, but not others? What is the Doppler effect and how would it let us know that a blazar is on its way? What are active galactic nuclei? Do radiation and gamma rays from blazars affect the Earth? How far is Markarian 421 from us?
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What If is a mini-documentary web series that takes you on an epic journey through hypothetical worlds and possibilities. Join us on an imaginary adventure through time, space and chance while we (hopefully) boil down complex subjects in a fun and entertaining way.
For decades, orbiters and tiny vehicles have roamed Mars, searching for signs of life. Get the latest scoop from Curiosity, a car-sized Mars rover with an impressive arsenal of scientific tools.
Season Five of Cosmic Vistas journeys into our solar system to experience unparalleled views of the sun, planets, and distant worlds. Cutting-edge scientific thinking and incredible imagery provide a brand new perspective on the cosmos.
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What is our place in the Milky Way? And our place in the Universe? In ancient times, many people had the idea our planet Earth to be at the centre of the Universe, as stated by Aristotle and Ptolomeus in their ptolemaic – aristotelic concept of universe: according to this model, Earth is at the center of the universe and all the other celestial bodies orbit around it. Today lots of people think the same. But is this really the case? To answer this question, let’s try to to a travel in the universe, through space and time; we will start our travel from our planet to reach, in the end, the extreme boundaries of the universe.
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During the 1600s, Galileo Galilei, the famous Italian astronomer, was one of the first people, during modern age, to have some doubts about the geocentric model of universe: thanks to telescopic observations, he was able to demonstrate our Earth is not at the rotation centre of planets and the Sun, but really it is the Sun itself. Moreover, observing planet Jupiter, he discovered that the giant planet is the rotation center for its moons. So, Galileo became aware that the center of the Solar System was the Sun, not the Earth!
The Solar System is made by a star, the Sun, eight planets and different types of minor celestial bodies, like comets, asteroids and dwarf planets.
Well, the Earth isn’t at the center of the Solar System, maybe is the closest planet to our Sun? No it isn’t, because it is only the third planet from the Sun: the closest planet to our star is Mercury, followed by Venus and then Earth. The Earth moves around the Sun, our star, just like all the other celestial bodies in the Solar System do: this implies that the Sun, and not our planet, is the center of rotation of the Solar System! The Earth takes a year, 365 days, to travel its orbit, and its average distance from the Sun is 150 million kilometers, which is the measure unit of distances in the Solar System known as the astronomical unit and abbreviated AU. Why do we talk about average distance? Because the orbit traveled by the Earth around the Sun is not circular but elliptical, and this means that there will be an aphelion (i.e. the point of the Earth’s orbit farthest from the Sun, just over 1 AU away from it) and a perihelion (the point of Earth’s orbit closest to the Sun, just under 1 AU). An alternative way to define the astronomical unit passes through the light time, in particular we can say that the average distance Earth – Sun is equal to about 8 light minutes: this means that sunlight takes 8 minutes to arrive on Earth, so that the sunlight we see at a certain moment is not that of that moment but it is the sunlight which left from the Sun 8 minutes earlier! In other words: if the sun went out for example at 2.30 pm, we would only notice it at 2.38 pm! Or again: if you could travel aboard the Star Wars Millennium Falcon it would take you only 8 minutes to travel from the Sun to the Earth (when in reality it takes a few years). To give a more concrete idea of the dimensions of the Solar System: if the Sun were a sphere with a diameter of 14 cm, Pluto would be at 700 m from the Sun, like seven regular soccer fields!
The nearest celestial body to Earth is the Moon, our satellite: to reach it you should take three days off! It’s the same time taken by Apollo astronauts to cover the distance of nearly 400 thousand kilometers that separate Moon and Earth. But if you had Star Trek Enterprise, and travel at maximum curvature, you would only take less than 2 seconds to reach the Moon!
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In recent years, people’s interest in all countries on the planet in space exploration has soared.
Many controversies have been raised regarding whether money should be spent on Space research while there are many problems in our inhabited planet, earth and especially in Humanity. There is poverty, financial issues. And still so much attention into Space exploration. Why?
Join me I show you reasons why Space research is very important.
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We have seen NASA announcing findings in other planets, solar systems and companies such as SpaceX undergo space projects. For instance we have determined the approximate age of the universe, we found water on Mars, we discovered the first exoplanets in 1992, between the years of 2004 and 2005 three new dwarf planets that exist in our solar system came into our attention and so much more.
But many keep on claiming. What is the point in all of this?
In order for a space exploration to happen, much money needs to be spent. For this reason many people seem to raise questions when it comes to space exploration whether money should be spent on space missions while there are many issues that are happening in our planet that we haven’t solved, and need financial support. So instead of exploring space, money should be spent for Earth’s needs.
Some others consider that, since we already visited the moon in 1969, we don’t need space travel anymore. isn’t it enough?
Well, there are many reasons why space exploration is important and I will try to explain my point of you on this topic and why space research is more significant than we think and vital to humanity.
Before we continue with the significance of space exploration, be sure to like or dislike the video so that we can continue improve and make these videos better for you the viewer. Plus, be sure to subscribe to the channel so that you don’t miss any of our weekly videos!
Now let’s start analyzing our topic.
Can you imagine the feeling the astronauts who first landed on the moon must felt looking back at the earth? Breaking through into space travel, leaving earth and defeating gravity, taking steps on the moon?
I bet the feeling would be unique! As they had the opportunity to see earth from a distance and be the first ones to acknowledge it! Imagine being in there position! I think many are jealous that they didn’t live this experience. For them this incident can’t be compared with anything else, and while we didn’t know at this time, this mission advanced our Humanity, and raised the interest on figuring out the Universe! Only goo results can come out of this as we are learning who we are and becoming strong.
But what is the real motive behind exploration. Why do you want to explore and go out of our comfort zone instead of carrying only about what is going on on Earth?
Well, the main reason why moon landing happened in 1969 and, is because humans are driven to explore the unknown, discover new worlds and push the boundaries of the scientific limits. Like it or not, we are by nature explorers who want tο push further and challenge the boundaries of what we already know and we want to learn always something new that can cause a whole new reality. We love exploring the world, travelling abroad visiting other countries and places, collecting memories and experiencing feelings. The same happens on a bigger level by exploring the universe. We are never satisfy and we always want more. People try to achieve these feats for reasons that are not necessarily rational. A few years ago we confirmed the existence of dark matter and we couldn’t do that without space exploration. What is the value of this knowledge? It’s hard to guess today.
And what keeps us going is the fact that we can discover everyday something new and in this way we advance human race. Imagination remains our most powerful attribute and we don’t want to stay stable in only one thing. That is what we do. We always explore. We overcome obstacles not because we have to, but because we want to. We can’t live without progress and curiosity is in our blood.
In this point we need to make clear that exploration isn’t just only about curiosity though, as exploration is necessary for advancement in general. If it wasn’t for the Space exploration we wouldn’t have advanced technologies.
The space research has led us to expand our scientific knowledge and have development of various technologies that improve our lives on Earth and also the economy. The world that we have created today, is the result of several years worth of knowledge, much of which has been built through exploration.
What would happen if the moon disappeared?
Our moon had a great status from the beginning of human civilization, it was immortalized by
various religions all around the world. In greek mythology there was a moon goddess named
Selene the daughter of the Titans Hyperion and Theia, it was worshiped and respected the
same way as the sun god Helios which indicates that our ancestors placed the moon and the
sun on equal footing. Moon is also worshiped in Hindu mythology by those who have
fluctuations in their life, ups and downs and by those who wish to have sons.
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The moon is featured in Van Gogh’s masterpiece “The starry night” , Frank Sinatra’s delightful song “Fly me
to the moon” and many other captivating art works. Art and history have always been enchanted
by the moon but today we intend to highlight the important role of the moon in elevating our
civilization from a scientific perspective. Our aim is to answer the question “ what would happen
if the moon disappeared? “
Before answering that question here are some facts about the moon:
1- The moon is the nearest and brightest celestial object orbiting the Earth in an elliptical path. It
may not follow the same path every cycle due to the fact that its orbit orientation is not entirely
fixed in space but rotates over time resulting in precession and inclination. Its apparent size
differs from the actual size due to the relative motion to an observer on the earth, you can
understand this as follows, the nearer an object to you the bigger you will see it.
2- The moon was formed 4.51 billion years ago approximately after 60 million years of the entire
formation of the solar system. There are several models regarding the moon formation but the
prevailing model is that the Earth-Moon system was formed due to an extremely huge impact
between a Mars sized celestial body called Theia and the proto-Earth, which is the earth at its
very early stages. The impact resulted in the Earth with its shape today and some other material
in its orbit which accreted and formed the moon.
3- Like the earth, the moon is a differentiated celestial body that can be divided into crust,
mantle and core. The Core is solid with a molten iron boundary around it, the mantle is the
largest layer formed by a complex yet extremely important process called the magma fractional
crystallization. The geo-chemical mapping of the moon rocks collected by the Apollo mission
suggests that the crust is mainly composed of mafic minerals which are rich in magnesium and
4- The photodecomposition process prevents the formation of water on the lunar surface. In
other words, the photons radiated by the sun decompose the water molecules formed on the
After knowing some interesting facts about the moon and how it was formed, It’s time to
consider the main question of today’s episode.
1- You may wonder what is exactly the relation between the moonlight absence and the
disturbance of the ecosystem because at the first glance they may seem completely unrelated,
however they are strongly connected. The ecosystem is by definition a biological community of
interacting organisms and their physical environment, it contains biotic and abiotic parts; the
biotic parts include all the living organisms whereas the abiotic components include the
environmental factors such as rocks, temperature and humidity. According to the encyclopedia
of national geographic, every factor in the ecosystem depends on every other factor either
directly or indirectly and the slight disturbance in one factor will end up affecting the whole
ecosystem; for example the change in temperature of an ecosystem will limit the type of plants
that grow in there and hence will affect the animals that depend on these plants as a primary
source of food and shelter leading them to adapt to that change or move to another ecosystem
or perish. Another important and related concept to highlight is the food chain; which describes
how energy and nutrients move through an ecosystem. In the food chain, energy is transferred
from one living organism through another in the form of food. There are primary producers such
as plants, primary consumers such as animals that depend on plants as their food source and
secondary consumers such as predators and decomposing organisms.
We know how terrifying and powerful black holes can be, but what comes second place in terms to it in terms of overall awesomeness? Join us today as we learn about neutron stars!
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One of the most popular outer space entities that pop culture love to revolve about is the black hole. We’ve seen various movies, TV programs, even some songs talk about how magnificent and mysterious they are. But what if black holes aren’t the only objects that we should be amazed with?
Of course we have a lot of picks for that matter, but the particular thing we would talk about today is the star that ranks number 1 in the universe in terms of density: the neutron stars.
Okay, astro fans, I can hear you argue and say “No, black holes are the densest objects in the universe!” But let me tell you this: remember how black holes work? They are effectively stars that collapsed to an almost zero volume, which results in their enormous gravitational force. If they effectively are dimensionless, can we really say that they are “objects”?
We can’t be really sure, and that’s something that only philosophy can answer, but while we’re here at the subject of definitions and what we actually know for certain, let’s just say the one we can categorize as the densest object, quote-unquote, is the neutron star.
And no, a neutron star is not a subatomic particle which grew to the size of the star. It isn’t also a bunch of neutrons agreeing to somehow collectively come together to form a humongous star. Although we can effectively say that a neutron star is like a giant atom, we’ll get to that later.
For now, I want to discuss how neutron stars are born and why they are like Phoenixes: how from the ashes of their old corpses, they rise up and fly with their new, replenished lives!
I know you already know this if you’re an astro buff, but to some of our viewers out there who are new, first of all, welcome! We hope we spark your curiosity more through our videos!
Anyway, stars were discovered to follow some kind of lifecycle, just like us living beings on Earth. They too, get born, have a childhood phase, then grow to adulthood, then also die, after certain circumstances.
A star’s usual routine involves fusing hydrogen into helium. Quite honestly, in its lifetime, that’s all it ever does. Now, as we know from basic nuclear physics, when we fuse atoms together, it creates energy. The energy that the fusion in the star creates is countered by the gravitational force towards its center, effectively keeping the balance and preventing it from collapsing towards its center. As long as this goes on, everything is good and well at a star’s life.
But of course, like all lives, stars experience a tipping point in theirs.
Remember how stars burn hydrogen to fuse to helium? Well, eventually, stars run out of hydrogen to fuse, so they fuse helium instead, forming elements such as carbon and oxygen. The energy pushes out the borders of the star causing it to move to its giant phase, until the pressure from electron degeneracy collapses the core of the star, and expelling its outer layer leaving a white dwarf.
For heavy mass stars, a number of times larger than the mass of our own Sun, the story is different.
The same as earlier, when the star runs out of hydrogen to fuse, it begins to fuse heavier elements. The difference this time is that the collapse caused by gravity is so extremely strong, way stronger than what we described earlier, that the fusion goes to Neon, to Oxygen, to Silicon, then finally to Iron.
As this happens, the outer layer of the star begins to fatten up faster as time goes by.
When the core of the star is finally iron, fusion can no longer take place, as iron is stubborn this way. We can imagine at this point, there is no more energy resulting from fusion. So what if that happens? The own weight of the star collapses in itself, effectively crushing it to the size of up to around a 10 kilometer radius. It’s like compressing the star to about the size of Malta!
Now, we know how subatomic particles don’t want to get near each other, right? We can practically say that an atom is made of empty space. However, the strength of the gravitational force that occurs when a heavy mass star collapses crushes this space in between, merging the protons and electrons together to form neutrons, with some neutrinos in excess.
But the extravaganza of energy doesn’t end there! See, neutrons hate being compressed towards one another, too. Just like protons and electrons. The collapse can only occur up to a certain moment where the neutrons form a lattice-like structure, the crushing in stops. By the way, this sudden halt is what we call neutron degeneracy pressure.
From the kind of star it is, to its impact on our world, and more! Join me as we explore the Sun: Facts and History.
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8. Our Star
Without a doubt, if you were to list the “most important things in the solar system we live in”, the Earth may be No.1, but the sun is No.2. And for all the reasons that you might expect and know.
Its gravity holds the solar system together, keeping everything from the biggest planets to the smallest particles of debris in its orbit. Electric currents in the Sun generate a magnetic field that is carried out through the solar system by the solar wind—a stream of electrically charged gas blowing outward from the Sun in all directions.
The connection and interactions between the Sun and Earth drive the seasons, ocean currents, weather, climate, radiation belts and aurora.
In short, and in long, the sun is vital to just about everything we do on this planet, and we rely on the sun to do MANY things, even though we’re honestly not controlling anything that it does. Which is a bit of an odd thing for humanity as humans like to control EVERYTHING that has to do with us.
The sun is something we see almost every day (obviously unless cloud cover is blocking it or an eclipse is happening) and even when we don’t see it, we feel its presence. It’s more than just a ball of light in the sky, it’s an energy source, a lifeline in many respects, and as noted above, it helps shape our planet in various ways that would detrimental if it WASN’T doing it.
So if someone was to honestly ask you just how important the sun is, you should tell them all the ways we need the sun, our star, to shine on.
7. Distance From Earth and Its Size
With a radius of 432,168.6 miles (695,508 kilometers), our Sun is not an especially large star—many are several times bigger—but it is still far more massive than our home planet: 332,946 Earths match the mass of the Sun. The Sun’s volume would need 1.3 million Earths to fill it.
Which at first might seem like a bad thing. After all, would we WANT to have a giant ball of fire and radiation just lurking out there that can swallow us whole if it felt like it? Honestly, yes, yes we would, and for a very simple reason, its distance from the Earth.
The Sun is 93 million miles (150 million kilometers) from Earth. Which is a very LONG ways away, and in fact it’s such a distance that they came up with a term for it via “Astronomical Unit”. So when you hear that a planet or star is say 103 AUs away, that means it’s 103 times the distance between the Earth and the sun.
Going back to the distance itself, you might think that this is a “very long way away” from the entity that gives us light and essentially, life. But actually, it’s better that we’re NOT closer to the sun for a whole host of reasons.
Sunlight and its energy dissipates the farther you get away from it. Which is why there is such thing as a “Habitable Zone” in regards to stars where life can exist as well as water and other key things needed for life.
The closer you are to a star, the more impact you’re going to get from its heat and light. The farther you are from a star, the less likely you’re going to get heat and light in the amounts you need. Lest you think we’re exaggerating this, we have the perfect examples for this. It’s called Mercury, Venus and Mars.
Mercury is the closest planet to the sun, and it’s scorching hot as a result. It’s average temperature is 800 degrees Fahrenheit. Plus, because it’s so close to the sun it’s tidally locked, meaning that it has one “side” always facing the sun, and the other side is always away from it.
In regards to Venus, it’s our “twin” but also a case of the suns energy turning it into something else entirely. A buildup of heat and excess carbon dioxide turned it into a “Runaway Greenhouse Planet” which makes it so hot that it can melt lead. And it’s also the hottest planet in the solar system because of the greenhouse effect which was caused by the suns’ radiation.
Heading to Mars, it’s so far away from the Sun that it can’t absorb the sunlight and energy like we do on Earth, so its average temperature is -81 degrees Fahrenheit. Not to mention it doesn’t have a typical atmosphere in any sense so various solar and cosmic rays bombard the planet. And it’s so far away from the sun that even if Earth settled on the planet, using solar panels to get energy for colonies wouldn’t be as viable as you think because the distance is so great.
So as you can see, it’s GOOD that we are 93 million miles away from the sun, it’s the literal perfect spot to be in to get the positive effects of the sun without many of the negatives.