Earth Archives

June 18, 2024June 18, 2024 by Evan Gough

Earth’s Atmosphere is Our Best Defence Against Nearby Supernovae

Artist's impression of a Type II supernova explosion. These supernova produce gamma rays and powerful ionizing radiation that's hazardous to life. Credit: ESO

Earth’s protective atmosphere has sheltered life for billions of years, creating a haven where evolution produced complex lifeforms like us. The ozone layer plays a critical role in shielding the biosphere from deadly UV radiation. It blocks 99% of the Sun’s powerful UV output. Earth’s magnetosphere also shelters us.

But the Sun is relatively tame. How effective are the ozone and the magnetosphere at protecting us from powerful supernova explosions?

June 11, 2024June 11, 2024 by Evan Gough

Was Earth’s Climate Affected by Interstellar Clouds?

About two million years ago, the Solar System may have passed through a dense cloud of hydrogen and radioactive material. It compressed the heliosphere, the protective cocoon the Sun provides for Earth and the other planets. It's shown here as the dark gray bubble over the backdrop of interstellar space. This could have exposed Earth to high levels of radiation and influenced the climate, and possible human evolution. Photo courtesy of Opher, et al., Nature Astronomy

Scientists scour the Earth and the sky for clues to our planet’s climate history. Powerful and sustained volcanic eruptions can alter the climate for long periods of time, and the Sun’s output can shift Earth’s climate over millions of years.

But what about interstellar hydrogen clouds? Can these regions of gas and dust change Earth’s climate when the planet encounters them?

May 7, 2024May 7, 2024 by Evan Gough

41,000 Years Ago Earth’s Shield Went Down

An illustration of Earth's magnetic field. Image Credit: ESA/ATG medialab

Earth is naked without its protective barrier. The planet’s magnetic shield surrounds Earth and shelters it from the natural onslaught of cosmic rays. But sometimes, the shield weakens and wavers, allowing cosmic rays to strike the atmosphere, creating a shower of particles that scientists think could wreak havoc on the biosphere.

This has happened many times in our planet’s history, including 41,000 years ago in an event called the Laschamps excursion.

May 6, 2024September 16, 2024 by Evan Gough

What Can Early Earth Teach Us About the Search for Life?

This view of Earth from space is a fusion of science and art, drawing on data from multiple satellite missions and the talents of NASA scientists and graphic artists. This image originally appeared in the NASA Earth Observatory story Twin Blue Marbles. Image Credits: NASA images by Reto Stöckli, based on data from NASA and NOAA.

Earth is the only life-supporting planet we know of, so it’s tempting to use it as a standard in the search for life elsewhere. But the modern Earth can’t serve as a basis for evaluating exoplanets and their potential to support life. Earth’s atmosphere has changed radically over its 4.5 billion years.

A better way is to determine what biomarkers were present in Earth’s atmosphere at different stages in its evolution and judge other planets on that basis.

April 30, 2024April 30, 2024 by Carolyn Collins Petersen

Earth Had a Magnetosphere 3.7 Billion Years Ago

The magnetic field and electric currents in and around Earth generate complex forces that have immeasurable impact on every day life. The field can be thought of as a huge bubble -- called the magnetosphere --, protecting us from cosmic radiation and charged particles that bombard Earth in solar winds. Credit: ESA/ATG medialab — The magnetic field and electric currents in and around Earth generate complex forces that have immeasurable impact on every day life. The field can be thought of as a huge bubble -- called the magnetosphere -- protecting us from cosmic radiation and charged particles that bombard Earth in solar winds. Credit: ESA/ATG medialab

We go about our daily lives sheltered under an invisible magnetic field generated deep inside Earth. It forms the magnetosphere, a region dominated by the magnetic field. Without that planetary protection shield, we’d experience harmful cosmic radiation and charged particles from the Sun.

April 3, 2024April 3, 2024 by Evan Gough

How Animal Movements Help Us Study the Planet

This map shows how elephants moved across Kruger National Park in South Africa over one year. Image Credit: Thaker, M., et al. (2019)

Scientists have been underutilizing a key resource we can use to help us understand Earth: animals. Our fellow Earthlings have a much different, and usually much more direct, relationship with the Earth. They move around the planet in ways and to places we don’t.

What can their movements tell us?

March 19, 2024March 19, 2024 by Mark Thompson

Gravity From Mars has an Effect on Earth’s Oceans

We are all too familiar of the Moon’s effect on our planet. It’s relentless tug causes our tides but even Mars, which is always at least 55 million kilometres away, can have a subtle effect too. A study has revealed a 2.4 million year cycle in the geological records that show the gentle warming and cooling of our oceans. The records match the interactions between the orbits of Earth and Mars over the longest timescales. These are known as the ‘astronomical grand cycles’ but to date, not much evidence has been found.

March 19, 2024March 19, 2024 by Evan Gough

Earth’s Long-Term Habitability Relies on Chemical Cycles. How Can We Better Understand Them?

Biogeochemical cycles move matter around Earth between the atmosphere, the oceans, the lithosphere, and living things. Image Credit: By Alexander Davronov - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=106124364

We, and all other complex life, require stability to evolve. Planetary conditions needed to be benign and long-lived for creatures like us and our multicellular brethren to appear and to persist. On Earth, chemical cycling provides much of the needed stability.

Chemical cycling between the land, atmosphere, lifeforms, and oceans is enormously complex and difficult to study. Typically, researchers try to isolate one cycle and study it. However, new research is examining Earth’s chemical cycling more holistically to try to understand how the planet has stayed in the ‘sweet spot’ for so long.

March 8, 2024March 8, 2024 by Matt Williams

Satellite Measurements Show That Global Carbon Emissions are Still Rising

Tracking carbon emissions and sinks to determine Earth's annual Global Carbon Budget. Credit: NASA GEOS

According to the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6), human activities have significantly impacted the planet. As global greenhouse gas emissions (mainly carbon dioxide) have continued to increase, so too have global temperatures – with severe ecological consequences. Between 2011 and 2020, global surface temperatures rose by an estimated 1.07 °C (2.01 °F) above the average in 1850–1900. At this rate, temperatures could further increase by 1.5 to 2 °C (2.7 to 3.6 °F) in the coming decades, depending on whether we can achieve net zero by 2050.

Unfortunately, the data for the past year is not encouraging. According to the 2023 Global Carbon Budget (GCB), an annual assessment of Earth’s carbon cycle, emissions in 2023 continued to rise by 1.1 percent compared to the previous year. This placed the total fossil fuel emissions from anthropogenic sources at 36.8 billion metric tons (over 40 US tons) of carbon dioxide, with an additional 4.1 billion metric tons (4.5 US tons) added by deforestation, extreme wildfires, and other sources. This trend indicates we are moving away from our goals and that things will get worse before they get better!

February 27, 2024February 27, 2024 by Evan Gough

See the Dramatic Final Moments of the Doomed ERS-2 Satellite

The ESA's ERS-2 Earth observation satellite was destroyed when it re-entered Earth's atmosphere on February 21st 2004. Heavy parts of satellites like reaction wheels don't don't always burn up in the atmosphere and can pose a hazard. ESA engineers are working on reaction wheels that will break into pieces to reduce the hazard. Image Credit: Fraunhofer FHR

When a satellite reaches the end of its life, it has only two destinations. It can either be maneuvered into a graveyard orbit, a kind of purgatory for satellites, or it plunges to its destruction in Earth’s atmosphere. The ESA’s ERS-2 satellite took the latter option after 30 years in orbit.