Science– category –
Clear explanations of space, physics and scientific evidence, with original diagrams and authoritative references.
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The Kardashev Scale: An Energy Framework, Not Proof of Alien Civilizations
English · 日本語 The Kardashev scale classifies hypothetical civilizations by the scale of energy they can use. It is an imaginative scientific framework, no... -
Galaxy Rotation Curves: What They Tell Us About Dark Matter
English · 日本語 A galaxy’s rotation curve plots orbital speed against distance from its centre. It is a way to investigate the gravitational field, not just... -
The Solar System’s Galactic Journey: Motion Depends on Your Reference Frame
English · 日本語 Earth orbits the Sun, but the Sun is also moving through the Milky Way. A planetary orbit drawn in a Sun-centred view and a planetary path d... -
How Long Will the Sun and Earth Last? Separate the Different Clocks
English · 日本語 “The Sun has billions of years left” and “Earth will remain comfortable for billions of years” are different claims. The first concerns a st... -
Dark Matter vs Dark Energy: Evidence, Unknowns and the Cosmic Budget
English · 日本語 Dark matter and dark energy are names for two different unresolved parts of cosmology. Dark matter helps explain gravitational effects that ... -
Why ISS Astronauts Float: Microgravity Is Not the Absence of Gravity
English · 日本語 Astronauts aboard the International Space Station float because they and the station are falling together around Earth. They are not beyond ... -
The Moon’s Far Side Is Not the Dark Side: Rotation and Sunlight Explained
English · 日本語 The Moon’s far side is not a permanently dark hemisphere. It receives sunlight as the Moon moves around Earth. “Far” tells us which side fac... -
What Is a Habitable Zone? Why It Does Not Mean a Second Earth
English · 日本語 A planet in a star’s habitable zone is a promising target for investigation, not a confirmed second Earth. The term describes a range of dis...
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