📖 Chapter 6 of 13 · Mysterious Space- Advance 2 · Class 9–10
Chapter 5: Deep Space and the Big Questions
The simple idea: to look far is to look back in time
Because light takes time to travel, the farther out we look, the further back in time we see. The most powerful telescopes gather faint light that left distant galaxies billions of years ago — so they show us the young Universe, long before the Earth existed. We cannot travel to the past, but we can photograph it, written in ancient light.
The technical layer: an expanding Universe with a beginning
When astronomers measured that almost every distant galaxy is moving away from us — and that farther ones move away faster — they realised the whole Universe is expanding, with space itself stretching. Running that expansion backwards points to a beginning about 13.8 billion years ago, when everything was unimaginably hot and dense: the event we call the Big Bang. Much remains unknown — what most of the Universe is made of, and how it will end — and those open questions are the frontier of modern science.
Story Time — A Photograph of the Past
Ishaan · Nagpur, Maharashtra
Ishaan, who had first seen Saturn through a telescope as a boy, now stood before a wall-sized image from a great space telescope: thousands of galaxies scattered across a single dark patch of sky. “How far away are these?” he breathed. “So far,” the astronomer said, “that their light has travelled for billions of years to reach this photograph.”
Ishaan did the arithmetic in his head and felt dizzy. “Then we are not seeing them as they are now. We are seeing them as they were — billions of years ago.” “You are looking at the young Universe,” the astronomer confirmed. “Some of these galaxies formed long before the Earth or the Sun existed. This is, quite literally, a photograph of the ancient past.”
“But how do we know the Universe even has a past — a beginning?” Ishaan asked. “Because it is expanding,” she said. “Nearly every distant galaxy is rushing away from us, the far ones fastest. Wind that expansion backwards, and everything crowds together, hotter and denser, until you reach a beginning about 13.8 billion years ago — the Big Bang.”
Ishaan stared at the countless galaxies, each a city of billions of stars, each shown as it was in the deep past. “And how much do we still not understand?” he asked. The astronomer laughed softly. “Most of it. We do not even know what most of the Universe is made of. The biggest questions are still open.”
Far from disappointing him, this thrilled Ishaan to his core. “So the greatest discoveries are still ahead.” “Waiting,” the astronomer said, “for minds patient enough to ask, and honest enough to admit what they do not yet know. Perhaps yours.” Ishaan bought a print of the image and hung it where he would see it every morning.
Story Time — Comfortable Not Knowing
Fatima · Lucknow
In Fatima's class, a student complained that science was frustrating. “Every answer just leads to more questions. Why can't we just know things?” Fatima, who had grown to love exactly this, waited to hear how the teacher would reply.
“Imagine,” the teacher said, “if everything were already known. There would be nothing left to discover, no frontier, no adventure. The unanswered questions are not a failure of science — they are the very reason it is alive.” She listed some of them: what most of the Universe is made of, how life began, whether it exists elsewhere, how the whole story will end.
“But isn't it uncomfortable,” the student pressed, “not having the answers?” “At first,” the teacher admitted. “Great scientists learn to be comfortable not knowing — to hold a question patiently, for years if need be, without grabbing a false answer just to feel settled. Saying ‘we do not yet know’ honestly is one of the bravest things a mind can do.”
Fatima finally spoke up. “So being a scientist is less about having answers and more about being at peace with good questions?” “Beautifully put,” the teacher said. “Certainty is easy and often wrong. Honest, patient uncertainty is how real understanding is built.”
The complaining student looked unconvinced, but Fatima felt something settle in her. She had always feared not knowing. Now she saw that the edge of knowledge — the place where the questions outnumber the answers — was not a frightening place at all. It was the most interesting place in the world, and she wanted to spend her life there.
Solved Examples
Think first, then read the answer.
1. Why is looking far into space also looking back in time?
Show answer
Answer: Because light takes time to travel, so distant light left long ago; we see faraway objects as they were in the past.
2. What did astronomers discover about distant galaxies?
Show answer
Answer: Almost all are moving away from us, and the farther ones move away faster — showing the Universe is expanding.
3. What does the expansion, run backwards, point to?
Show answer
Answer: A hot, dense beginning about 13.8 billion years ago, called the Big Bang.
4. Name one thing scientists still do not know about the Universe.
Show answer
Answer: What most of it is made of, how life began, or how the Universe will end.
5. Why are open questions valuable in science?
Show answer
Answer: They are the living frontier — the reason discovery continues, waiting for patient, honest minds.
Check Your Understanding
A. Fill in the blanks
- To look far into space is to look back in _______.
- Distant galaxies are moving _______ from us.
- The hot, dense beginning is called the Big _______.
B. Write True or False
- The Universe is expanding. ( ___ )
- We can see distant galaxies exactly as they are now. ( ___ )
- Scientists already understand everything about the Universe. ( ___ )
C. Short answer
- Explain how a photo of distant galaxies is 'a photograph of the past.'
- Why can it be brave to say 'we do not yet know'?
D. Reflect
- In the Space Lab, what did the expanding-Universe tool show you?
- Which big open question would you most like answered?
- Do you find not-knowing frightening or exciting? Explain.
Check your understanding
Tap an answer to see if it is correct. This is just for fun — nothing is saved.
1. Looking far into deep space means seeing...
- The future
- The past
- Nothing
Show answer
B. The past
2. Distant galaxies are mostly...
- Moving away from us
- Standing still
- Falling on us
Show answer
A. Moving away from us
3. The Big Bang was...
- A star exploding
- The hot, dense beginning of the Universe
- A black hole
Show answer
B. The hot, dense beginning of the Universe