The vast universe hides secrets that space science still hasn’t fully solved. Some mysteries have been explored—planets, stars, Earth’s gravity—but many still baffle astrophysicists: what lies inside black holes, dark matter, the end of the universe…
The Cosmic Mysteries We’re Still Chasing
- What is the universe made of?
- Are we alone in the universe?
- What’s inside a black hole?
- How can we harness more energy from the Sun?
- The possibility of life on Mars
- The origin of ultra-high-energy cosmic rays
- Where fast radio bursts (FRBs) come from
- Why there is more matter than antimatter
- The Fermi Bubbles
- A rectangular galaxy
- The Moon’s magnetic field
- Why pulsars
Below are some of the toughest space questions that humans are still “racking our brains” to answer.
What Is the Universe Made Of?
Scientific announcements about the Solar System and the Milky Way make many people confident in our understanding of the cosmos. But the surprising truth is that we’ve identified only about 5% of what makes up the universe beyond Earth.
In reality, everything we can directly detect in the universe is “luminous” matter: the chemical elements, molecules, atoms, and their subparticles (protons, electrons, neutrons…). These are the building blocks of Earth—yet they amount to only 1/20 of the universe.
So what is the other 95%? We know it exists, but we can’t see or directly study it because it’s invisible. It’s dark matter (~25% of the universe) and dark energy (~70% of the universe).
Dark matter doesn’t emit light and is thought to surround galaxies and galaxy clusters—experts call it an “invisible cloak.” We infer its existence from its mass and the gravitational pull it exerts on visible matter.
Dark energy is even more mysterious. It’s thought to be a form of energy permeating the universe that accelerates the motion of galaxies—pushing them closer or farther apart. A precise theory still doesn’t exist, and scientists remain stumped.
Are We Alone in the Universe?
Ever since space science began, one question has haunted humanity: Is there anyone out there? We’ve launched spacecraft and explored many worlds in search of life, but so far, no definitive answer.
Many hypotheses guide research, notably the multiverse theory, a concept dating back to William James (1895), suggesting that many universes may exist alongside our own.
From this framework, modern studies often propose that we may have “neighbors” on other planets—or in other universes. In 2011, to probe this question, some U.S. scientists used state-of-the-art technology to broadcast radio signals into space. If detected by extraterrestrials, they might send signals back to Earth. By this method, they argued, within about 20 years we could tell whether alien civilizations exist.
What’s Inside a Black Hole?
A black hole is the remnant of a massive star that collapses under its own gravity. It’s a cosmic “devourer” that can swallow planets, celestial bodies—even light—if they cross its event horizon.
What lies inside remains unknown. We do know black holes have immense gravity and anything that falls in vanishes without a trace.
Many hypotheses exist. A 2013 article in New Scientist suggested black holes might not destroy what they consume. Instead, a black hole could act as a cosmic gateway, ejecting matter into another universe, hinting at research paths for humanity’s dream of space-time travel.
How Can We Harness More Energy from the Sun?
Humanity faces a persistent energy crisis as fossil fuels run out. The search for alternatives continues, and solar energy is often seen as a savior.
Yet in practice, solar energy isn’t fully utilized. Despite technological progress, solar-cell efficiency remains relatively low—around 16%—and natural conditions limit where solar can be used effectively.
The big question: can we truly tap this abundant, virtually limitless resource to solve Earth’s energy challenges? Scientists are still working hard on the answer.
The Possibility of Life on Mars
Life may have existed on Mars—and might even persist today. Mars once had vast oceans. Scientists have found evidence that liquid water still flows intermittently on its surface. Multiple nations are planning crewed missions to investigate further.
The Origin of Ultra-High-Energy Cosmic Rays
Cosmic rays are high-speed particles that travel through space and sometimes strike Earth. Their origins remain unclear. Low-energy cosmic rays come from the Sun as solar wind (charged particles), but identifying the sources of high-energy cosmic rays is harder because magnetic fields in interstellar space deflect their paths, according to astrophysicists at CERN.
Where Do Fast Radio Bursts (FRBs) Come From?
FRBs are millisecond-long bursts of radio waves from deep space. Like cosmic rays, their sources are unknown. One hypothesis links them to the same origins as some cosmic rays; others argue FRBs may arise from rare, non-repeating events.
Why Is There More Matter Than Antimatter?
When a particle meets its antiparticle, they annihilate. If matter and antimatter were created in equal amounts, the universe shouldn’t exist. Theory says the Big Bang produced equal quantities—yet, somehow, there’s more matter. Pinpointing what happened to antimatter is one of physics’ greatest challenges, say researchers at CERN.
The Fermi Bubbles
These are enormous, mysterious structures extending about 20,000 light-years above and below the Milky Way’s plane, discovered in 2010. Invisible to the naked eye, they emit high-energy gamma and X-rays. Scientists suspect the gamma rays may be shock waves from stars consumed by the Milky Way’s central supermassive black hole. Even today, the origin of the Fermi Bubbles remains elusive.
A Rectangular Galaxy
Astronomers from Australia, Germany, Switzerland, and Finland discovered a strange galaxy about 70 million light-years away—LEDA 074886—with a rectangular shape. While most galaxies are disks, 3D ellipses, or irregular blobs, some speculate this shape formed from a collision of two spiral galaxies. No precise, universally accepted explanation exists yet.
The Moon’s Magnetic Field
A long-standing lunar puzzle inspired even science-fiction tales like 2001: A Space Odyssey: why do only certain regions of the Moon’s surface show magnetism?
After extensive tests and surface analyses, scientists think the Moon once had a global magnetic field—around 4.5 billion years ago (ancient in lunar history). Over time, as the angle between the Moon’s crust and core changed and the Moon drifted farther from Earth, lunar tidal forces weakened—and the magnetic field faded.
Why Do Pulsars Pulse?
A pulsar is a distant, rapidly rotating neutron star emitting beams of electromagnetic radiation at regular intervals—like a lighthouse beam sweeping the shore. Despite the first discovery in 1967, scientists long wondered why pulsars pulse and why some stop intermittently.
In 2008, when one pulsar abruptly ceased pulsing for 580 days, researchers found that the on/off intervals are linked to the pulsar’s own electromagnetic field, which slows its rotation. Astronomers are still studying why the field varies.
How Will the Universe End?
Astronomers estimate the Sun will destroy Earth in about 6 billion years. Several hypotheses address the universe’s ultimate fate:
- Heat Death (Thermodynamics): the universe ends when everything reaches the same temperature; stars burn out, matter dissipates.
- Big Crunch: the universe keeps expanding until gravity ultimately reverses it, collapsing everything into a super-dense state—a complete end.
Which scenario will come to pass? For now, the cosmos keeps its final secret.
