theSIGNAL SCIENCE
2 September 2026
"The universe is under no obligation to make sense to you."
NEWSBUSINESSTECHNOLOGYWORLDSCIENCECULTUREENVIRONMENTSPORT
Science

Our Sun's Galactic Road Trip Shaped Life on Earth

Two NASA-funded studies reveal that the Sun's ancient journey through the Milky Way may have quietly steered Earth's climate for billions of years.

Here is a strange thought. The Sun has been travelling. For 4.6 billion years, it has been looping around the centre of the Milky Way, dragging every planet, moon, and comet with it — and passing through wildly different galactic neighbourhoods along the way.

Now, two NASA-funded studies suggest that this cosmic road trip was not merely scenic. It may have shaped Earth's climate, its ice ages, and even the conditions that allowed life to begin. The first study, published on 21 August in the Annual Review of Astronomy and Astrophysics, comes from NASA's SHIELD centre. Researchers used computer simulations to trace the heliosphere's ancient path through the galaxy.

The heliosphere is the enormous bubble of charged particles that the Sun continuously blows outward in every direction, forming a kind of magnetic shield around the entire solar system. When that shield passed through denser or more turbulent regions of the Milky Way, the team argues, cosmic radiation and other galactic forces may have leaked through — potentially triggering the temperature swings that scientists associate with major ice ages on Earth. Scientists had previously focused on orbital mechanics and greenhouse gases to explain those dramatic cold spells. Galactic geography was not really on the list.

The second puzzle is older and, in some ways, weirder.

Photo: NASA Hubble Space Telescope / Unsplash
A visualisation of the heliosphere, the Sun's vast protective bubble, travelling through interstellar space.
Discuss
  • What is the heliosphere, and why might its size or strength matter for life on Earth?
  • Why did scientists previously focus on orbital mechanics rather than galactic geography to explain ice ages?
  • The 'faint young Sun paradox' suggests early Earth should have been frozen. Does this change how you think about the conditions needed for life?
Science

Space Microbes Could Break Earth's Laws

Japan's Hayabusa2 probe found uracil — a building block of RNA — on a near-Earth asteroid. NASA's Europa Clipper is already sailing toward Jupiter's moons, hunting for signs of life. Here is the strange part: if scientists found a microbe that originated somewhere other than Earth, no existing law would quite know what to do with it. The Outer Space Treaty, signed in 1967, was never designed for extraterrestrial biology. Researchers argue that the gap between what space missions can discover and what international policy can handle is growing wider every year.…
  • If a microbe from Mars were discovered today, who should decide humanity's response?
∞
The heliosphere is the vast protective bubble produced by the Sun that surrounds the solar system, and changes in the galactic environment around this bubble may have affected conditions on Earth.
Merav Opher, Principal Investigator, NASA SHIELD Science Centre
Science

Plants That Mine the Earth for You

One small field plant — pennycress — could help solve a crisis bigger than it looks. Scientists at Oak Ridge National Laboratory in Tennessee are engineering crops to pull critical minerals like nickel and cobalt straight out of the soil, no mine shaft required. The trick is speed. Analysing over 1,000 plant traits once took hundreds of human hours. Now an AI system, powered by the Frontier supercomputer, does it in minutes. The minerals hiding inside your smartphone may one day have grown in a field.…
  • Should countries prioritise plant-based mining over traditional extraction methods?
WORLD · Science
The universe is still speeding up, but nobody knows why
GLOBAL · Science
'A giant leap forward': Nasa launches powerful new space telescope
AMERICAS · Science
NPR spent 2 years tracking deaths from heat. We found a staggering hidden toll
OCEANIA · Science
Hundreds of hidden earthquakes found at Antarctica’s Doomsday Glacier
theSIGNAL IN THE LAB
1VOCABULARY
heliospherecosmic radiation
faint young Sun paradoxgreenhouse gasesuracil
extraterrestrialsupercomputer
2GRAMMAR FOCUS
Cleft sentences — It was X that / What X is/did
Cleft sentences split one idea into two clauses to emphasise a particular element. 'It was X that...' highlights a specific detail, while 'What...' clauses front the most important information and link it with 'is' or 'was'.
It was · What · that · is · was · which · who
  1. the heliosphere passing through denser galactic regions ___ may have allowed cosmic radiation to leak through to Earth.
  2. It NASA's SHIELD centre ___ used computer simulations to trace the heliosphere's ancient path through the Milky Way.
  3. scientists find genuinely exciting is not just the answers, but what the questions reveal about Earth itself.
  4. It the discovery of uracil on a near-Earth asteroid ___ raised urgent questions about extraterrestrial biology.
  5. the Outer Space Treaty of 1967 failed to address was the possibility of discovering actual living organisms in space.
  6. It the AI system powered by the Frontier supercomputer ___ reduced plant trait analysis from hundreds of hours to minutes.
3COLLOCATIONS
Match the verb on the left with the noun phrase it best collocates with on the right.
  1. trace
  2. trigger
  3. forge
  4. sign
  5. analyse
4CRITICAL THINKING
The articles suggest that both Earth's climate and the origins of life may have been shaped by factors entirely outside human control or prediction — galactic position, solar eruptions, and asteroid chemistry. If the conditions for life on Earth were this dependent on cosmic coincidence, what does that imply about how confidently we can search for life elsewhere, or design policies to protect life here?
5CREATIVE · HEADLINES
Write a headline for the top story in each of the following styles. One line each, no explanation:
  • TABLOID NEWSPAPER
  • LUXURY MAGAZINE
  • ACTIVIST BLOG
6WRITING
Some scientists argue that understanding Earth's deep past — including galactic influences and ancient solar activity — is just as urgent as studying present-day climate change. Write a short opinion piece arguing either that deep-time science deserves more funding, or that limited resources should focus on immediate environmental challenges.
7DEGREES OF EXTREMITY
Complete each ladder from mild to strong.
  • warm→→
  • cold→→
  • unusual→→
  • bright→→
  • turbulent→→
  • concerned→→
8SPEAKING
  1. Could plant-based mining ever fully replace traditional methods?
  2. How might the faint young Sun paradox change the search for exoplanets?
  3. Should space law be rewritten before missions return samples?
  4. Which discovery from the articles affects daily life most directly?