Stars, planets, black holes, celestial bodies, extraterrestrial life…
“The universe we wanted to know is all here!”

250,000 YouTube subscribers "Space Dust's Sage Times"
Astronomer Dr. Ji Woong-bae guides you on this wondrous space exploration.

There are questions that everyone has thought about at least once, but for which it is difficult to get a clear answer.
"Strange Questions That Come to Mind When You Look at the Universe" is a fascinating book that explores astronomical knowledge based on small but essential curiosities about the universe.
The author presents the core concepts of modern astronomy in an accessible and engaging way, gathering frequently asked questions and addressing the hottest topics in the astronomy world today.
This book provides an experience that naturally expands scientific thinking by adding intuitive examples and explanations that help visual imagination so that even those without basic scientific knowledge can understand it.
Taking the time to understand what we see with our eyes, such as stars and the sun, and what we cannot see with our eyes, such as extraterrestrial life, undiscovered planets, and black holes, is like understanding the meaning of the universe that surrounds our existence.
As can be seen from the part where we look at the similarities between the human brain, nicknamed the '1.4kg universe', and the universe, the connection between the universe and humans is very deep.
Ultimately, if you seek to know the universe, you will come to know yourself, and a vast opportunity will open up to see worlds beyond Earth.
At the doorstep of the vast universe, let's meet a new and diverse educational book for Earthlings.

Science provides logical explanations for why things that seem obvious must be obvious.
Science finds a reason in everything.
The word "obvious" does not exist in the dictionary of science.
Neither clouds floating in the sky nor water flowing from above are natural.
There must be some hidden principle or law that makes it inevitable that such things will happen.
--- From "Introduction"

Why is space dark? We're now one step closer to a better answer to this question.
Long ago, mankind believed that the universe had existed endlessly since the infinite past, and that therefore, we should be able to see all the light from the infinite number of stars in the universe without missing a single one.
Naturally, the universe could not be dark.
But now we know that the extent of the universe, at least as far as light can see, is finite.
The universe did not live infinitely long ago, and there are limits to the extent of the universe we can see.
Our observable universe is finite.
--- From "Why is space dark?"

Imagine reading a letter from a bottle abandoned on the beach. Imagine Robinson Crusoe, stranded on a deserted island, discovering a letter he'd left floating in the ocean.
Even if you take the letter out of the bottle and read it, the letter must have been written long before the day the bottle was discovered.
Because the speed at which sea water flows is slow and finite.
It takes a long time for a bottle to travel by seawater from a distant, uninhabited island to the shore where I stand.
I have no choice but to read letters written in the past for that amount of time.
It's the same in space.
--- From "Where is the end of the universe?"

If we look at it this far, it seems like we have a pretty good understanding of how galaxies were born, but that's not the case.
The story I've just explained is actually something that happened very recently in the entire evolutionary history of galaxies.
In terms of human history, this corresponds to modern and contemporary history.
We don't know anything about how the first galaxy was born in the universe immediately after the Big Bang, what the seed that created the first galaxy looked like, or what process it went through to grow.
Now we have only a vague idea of ​​the modern and contemporary history of the universe, but we know nothing about the ancient history of the universe.
--- From "Why is our galaxy flat?"

The sun does not shine forever.
The sun is also an ordinary star.
All stars die someday.
When a star's fuel is exhausted and the spark of nuclear fusion dies, the star meets its end.
Even if Earth is lucky enough to avoid all the catastrophes that occur in space, the death of the Sun is inevitable.
One of the most astronomically certain fates of the Earth is that the Sun will lose its light and the Earth will disappear with it.
Fortunately, there is no need to worry right now.
Because it's something that will happen in about 5 billion years.

--- From "What happens when the sun dies?"

If we miss even one of the smaller asteroids, the damage will be localized, such as the disappearance of some cities, although the entire Earth may not disappear.
Ultimately, we end up in a difficult dilemma: whether the asteroid is too big or too small is a problem.
The most important thing is to build as many surveillance networks as possible to detect and respond to even smaller asteroids as early as possible.
There are still countless threatening celestial bodies lurking around Earth that have yet to be detected.
Now our survival depends on how often we look up at the night sky during our daily lives.
--- From "Can we protect the Earth from an asteroid impact?"

If there's another planet in our solar system, still lurking, undetected, what would the solar system look like from that distant vantage point? This unknown ninth planet would likely be even farther away than the Voyager probes.
It feels like we're literally teetering on the edge of the solar system.
Because the sun is so far away, it takes five days for sunlight to reach us.
On Earth, we see sunlight eight minutes ago every moment, but here, we see sunlight five days ago every day.
--- From "Is there another planet hiding beyond Pluto?"

As astronomer Carl Sagan once said, we are all made of stardust left behind by supernovae.
From the time of the Big Bang until now, over the past 13 billion years, countless supernovae have exploded, and the various heavy elements left behind by those explosions have accumulated and formed us.
The teachings of the supernovas are engraved in our bodies.
But perhaps the supernova's role was simply to leave behind the materials that would create life on Earth.
--- From "What would happen if a supernova exploded around Earth?"

To explore the birth of the universe and life, we must have the engineering skills to send probes further into space.
But paradoxically, to fully enjoy the universe as it is, we must escape to a primitive environment, where human technology is least intrusive and least developed.
That's why the world's largest telescopes are located in places untouched by human hands, such as volcano peaks, arid deserts on high plateaus, and the freezing cold of Antarctica.
Because, far from human intervention, away from the light pollution of city lights, we can see the universe at its quietest and most complete.
--- From "Will Starlink Satellites Interfere with Night Sky Observations?"

If you don't want to lose hope of an alien civilization, you can also expect to see fragments of destroyed planets and spaceships from the Galactic Empire's devastating wars in the distant past, just like in the epic Star Wars, orbiting the Tabby Star.
In addition to Tabby Star, stars that exhibit unusual brightness variations that are difficult to explain are still occasionally discovered.
Maybe those stars really do hold the alien civilization we've been waiting for.

--- From "Can we find extraterrestrial civilizations beyond extraterrestrial life?"