The Planet Inside

Scientists are probing the secrets of the inner core—and learning how it might have saved life on Earth.

A Solution to the Faint-Sun Paradox Reveals a Narrow Window for Life

Back when the sun was 30% dimmer, Earth should have frozen solid. Yet water flowed and life blossomed. The solution to the paradox shows that we might have that faint sun to owe for life’s existence — with critical consequences for the possibility of life outside Earth.

In the early solar system, a close-orbiting moon would have contorted Earth’s interior, heating it from within. James O’Brien for Quanta Magazine

‘Snowball Earth’ Might Be Slushy

Imagine a world without liquid water—just solid ice in all directions. It would certainly not be a place that most life forms would like to live.

A diagram showing two theories on glaciation on early Earth (from 716.5 to 630 million years ago)

Researchers find that Earth’s magnetic shield is 500 million years older than previously thought

An older geomagnetic field suggests an early start to plate tectonics.

An artist’s depiction of Earth’s magnetic field deflecting high-energy protons from the sun four billion years ago. Note: The relative sizes of the Earth and Sun, as well as the distances between the two bodies, are not drawn to scale. Source: University of Rochester

The Planetary Sweet Spot

Geochemist Matthew Jackson argues that the abundance of certain elements in the Earth dictate whether plate tectonics can happen.

Earthrise, 12/24/1968

This view of the rising Earth greeted the Apollo 8 astronauts as they came from behind the Moon after the fourth nearside orbit. The photo is displayed here in its original orientation, though it is more commonly viewed with the lunar surface at the bottom of the photo. Earth is about five degrees left of the horizon in the photo. The unnamed surface features on the left are near the eastern limb of the Moon as viewed from Earth. The lunar horizon is approximately 780 kilometers from the spacecraft. Height of the photographed area at the lunar horizon is about 175 kilometers. 

NASA

Earthrise, December 24, 1968

In December of 1968, the crew of Apollo 8 became the first people to leave our home planet and travel to another body in space. But as crew members Frank Borman, James Lovell, and William Anders all later recalled, the most important thing they discovered was Earth.

Using photo mosaics and elevation data from Lunar Reconnaissance Orbiter (LRO), this video recreates the moment when the crew first saw and photographed the Earth rising from behind the Moon. Narrator Andrew Chaikin, author of A Man on the Moon, sets the scene for a three-minute visualization of the view from both inside and outside the spacecraft accompanied by the onboard audio of the astronauts.

The visualization draws on numerous historical sources, including the actual cloud pattern on Earth from the ESSA-7 satellite and dozens of photographs taken by Apollo 8, and it reveals new, historically significant information about the Earthrise photographs. It has not been widely known, for example, that the spacecraft was rolling when the photos were taken, and that it was this roll that brought the Earth into view. The visualization establishes the precise timing of the roll and, for the first time ever, identifies which window each photograph was taken from.

Planet Earth Control Deck

via tabletopwhale.com

Eleanor Lutz, the author of this infographic, wanted to show what Earth’s control panel might look like if it was a spaceship piloted by humans. All of the data – as the author wrote – should be scientifically accurate, even if it’s moving too fast to read properly.

A snow line, a dead zone and a nearly dry planet

With large swaths of oceans, rivers that snake for hundreds of miles, and behemoth glaciers near the north and south poles, Earth doesn't seem to have a water shortage. And yet, less than one percent of our planet's mass is locked up in water, and even that may have been delivered by comets and asteroids after Earth's initial formation.

The shadow of the Moon

At around 7:34 a.m. on May 21 (Mon.), an annular solar eclipse was observed from many places in Japan including metropolitan areas. At that time, the Quasi-Zenith Satellite-1 “MICHIBIKI” shot images of the Earth from space. You can see that the area above Japan was blackened because it was shaded by the moon due to the eclipse. In addition to the MICHIBIKI, the Solar Physics Satellite “HINODE” also captured some images of the solar eclipse.

Shadow of the Moon on Earth caused by the solar eclipse. Credit: JAXA

Source:

• Quasi-Zenith Satellite-1 "MICHIBIKI", JAXA, May 21, 2012

A dry planet, after all

This picture shows the size of a sphere that would contain all of Earth's water in comparison to the size of the Earth. The blue sphere sitting on the United States, reaching from about Salt Lake City, Utah to Topeka, Kansas, has a diameter of about 860 miles (about 1,385 kilometers) , with a volume of about 332,500,000 cubic miles (1,386,000,000 cubic kilometers). The sphere includes all the water in the oceans, seas, ice caps, lakes and rivers as well as groundwater, atmospheric water, and even the water in you, your dog, and your tomato plant.

All of Earth's Water in a Single Sphere. Credit: Jack Cook, Woods Hole Oceanographic Institution (© Howard Perlman, USGS)

Sources:

• Water Science for Schools, USGS, May 10, 2012
• All the Water on Planet Earth, APOD, May 15, 2012

A giant image of the Earth globe

Electro-L, a geostationary Russian weather satellite launched on January 20th, 2011, produced a very detailed total view of the Earth, centered over the Indian Ocean. This image has a much more higher resolution than the famous "blue marble" photograph of the Earth, taken in 1972 by the Apollo 17 crew. The orange color represents vegetation.

Earth as seen from Russian weather satellite Electro-L. The full size image is about 110 Mb. Credit: NTs OMZ