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As the Worlds Turn: Visualizing the Rotation of Planets

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As the Worlds Turn: Visualizing the Rotations of Planets

The rotation of planets have a dramatic effect on their potential habitability.

Dr. James O’Donoghue, a planetary scientist at the Japanese space agency who has the creative ability to visually communicate space concepts like the speed of light and the vastness of the solar system, recently animated a video showing cross sections of different planets spinning at their own pace on one giant globe.

Cosmic Moves: The Rotation of the Planets

Each planet in the solar system moves to its own rhythm. The giant gas planets (Jupiter, Saturn, Uranus, and Neptune) spin more rapidly on their axes than the inner planets. The sun itself rotates slowly, only once a month.

PlanetRotation Periods (relative to stars)
Mercury58d 16h
Venus243d 26m
Earth23h 56m
Mars24h 36m
Jupiter9h 55m
Saturn10h 33m
Uranus17h 14m
Neptune16h

The planets all revolve around the sun in the same direction and in virtually the same plane. In addition, they all rotate in the same general direction, with the exceptions of Venus and Uranus.

In the following animation, their respective rotation speeds are compared directly:

The most visually striking result of planetary spin is on Jupiter, which has the fastest rotation in the solar system. Massive storms of frozen ammonia grains whip across the surface of the gas giant at speeds of 340 miles (550 km) per hour.

Interestingly, the patterns of each planet’s rotation can help in revealing whether they can support life or not.

Rotation and Habitability

As a fish in water is not aware it is wet, so it goes for humans and the atmosphere around us.

New research reveals that the rate at which a planet spins is an essential component for supporting life. Not only does rotation control the length of day and night, bit it influences atmospheric wind patterns and the formation of clouds.

The radiation the Earth receives from the Sun concentrates at the equator. The Sun heats the air in this region until it rises up through the atmosphere and moves towards the poles of the planet where it cools. This cool air falls through the atmosphere and flows back towards the equator.

This process is known as a Hadley cell, and atmospheres can have multiple cells:

Hadley Cells

A planet with a quick rotation forms Hadley cells at low latitudes into different bands that encircle the planet. Clouds become prominent at tropical regions, which reflect a proportion of the light back into space.

For a planet in a tighter orbit around its star, the radiation received from the star is much more extreme. This decreases the temperature difference between the equator and the poles, ultimately weakening Hadley cells. The result is fewer clouds in tropical regions available to protect the planet from intense heat, making the planet uninhabitable.

Slow Rotators: More Habitable

If a planet rotates slower, then the Hadley cells can expand to encircle the entire world. This is because the difference in temperature between the day and night side of the planet creates larger atmospheric circulation.

Slow rotation makes days and nights longer, such that half of the planet bathes in light from the sun for an extended period of time. Simultaneously, the night side of the planet is able to cool down.

This difference in temperature is large enough to cause the warm air from the day side to flow to the night side. This movement of air allows more clouds to form around a planet’s equator, protecting the surface from harmful space radiation, encouraging the possibility for the right conditions for life to form.

The Hunt for Habitable Planets

Measuring the rotation of planets is difficult with a telescope, so another good proxy would be to measure the level of heat emitted from a planet.

An infrared telescope can measure the heat emitted from a planet’s clouds that formed over its equator. An unusually low temperature at the hottest location on the planet could indicate that the planet is potentially a habitable slow rotator.

Of course, even if a planet’s rotation speed is just right, many other conditions come into play. The rotation of planets is just another piece in the puzzle in identifying the next Earth.

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Mapped: The Geology of the Moon in Astronomical Detail

Behold the glory of the Unified Geologic Map of the Moon, which brings decades of data into one map, revealing the potential for exploration.

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Geologic Map of the Moon

Mapped: The Geology of the Moon in Astronomical Detail

If you were to land on the Moon, where would you go?

Today’s post is the incredible Unified Geologic Map of the Moon from the USGS, which combines information from six regional lunar maps created during the Apollo era, as well as recent spacecraft observations.

Feet on the Ground, Head in the Sky

Since the beginning of humankind, the Moon has captured our collective imagination. It is one of the few celestial bodies visible to the naked eye from Earth. Over time different cultures wrapped the Moon in their own myths. To the Egyptians it was the god Thoth, to the Greeks, the goddess Artemis, and to the Hindus, Chandra.

Thoth was portrayed as a wise counselor who solved disputes and invented writing and the 365-day calendar. A headdress with a lunar disk sitting atop a crescent moon denoted Thoth as the arbiter of times and seasons.

Artemis was the twin sister of the sun god Apollo, and in Greek mythology she presided over childbirth, fertility, and the hunt. Just like her brother that illuminated the day, she was referred to as the torch bringer during the dark of night.

Chandra means the “Moon” in Sanskrit, Hindi, and other Indian languages. According to one Hindu legend, Ganesha—an elephant-headed deity—was returning home on a full moon night after a feast. On the journey, a snake crossed his pathway, frightening his horse. An overstuffed Ganesha fell to the ground on his stomach, vomiting out his dinner. On observing this, Chandra laughed, causing Ganesha to lose his temper. He broke off one of his tusks and hurled it toward the Moon, cursing him so that he would never be whole again. This legend describes the Moon’s waxing and waning including the big crater on the Moon, visible from Earth.

Such lunar myths have waned as technology has evolved, removing the mystery of the Moon but also opening up scientific debate.

Celestial Evolution: Two Theories

The pot marks on the Moon can be easily seen from the Earth’s surface with the naked eye, and it has led to numerous theories as to the history of the Moon. Recent scientific study brings forward two primary ideas.

One opinion of those who have studied the Moon is that it was once a liquid mass, and that its craters represent widespread and prolonged volcanic activity, when the gases and lava of the heated interior exploded to the surface.

However, there is another explanation for these lunar craters. According to G. K. Gilbert, of the USGS, the Moon was formed by the joining of a ring of meteorites which once encircled the Earth, and after the formation of the lunar sphere, the impact of meteors produced “craters” instead of arising from volcanic activity.

Either way, mapping the current contours of the lunar landscape will guide future human missions to the Moon by revealing regions that may be rich in useful resources or areas that need more detailed mapping to land a spacecraft safely .

Lay of the Land: Reading the Contours of the Moon

This map is a 1:5,000,000-scale geologic map built from six separate digital maps. The goal was to create a resource for science research and analysis to support future geologic mapping efforts.

Mapping purposes divide the Moon into the near side and far side. The far side of the Moon is the side that always faces away from the Earth, while the near side faces towards the Earth.

The most visible topographic feature is the giant far side South Pole-Aitken basin, which possesses the lowest elevations of the Moon. The highest elevations are found just to the northeast of this basin. Other large impact basins, such as the Maria Imbrium, Serenitatis, Crisium, Smythii, and Orientale, also have low elevations and elevated rims.

Shapes of Craters

The colors on the map help to define regional features while also highlighting consistent patterns across the lunar surface. Each one of these regions hosts the potential for resources.

Lunar Resources

Only further study will resolve the evolution of the Moon, but it is clear that there are resources earthlings can exploit. Hydrogen, oxygen, silicon, iron, magnesium, calcium, aluminum, manganese, and titanium are some of the metals and minerals on the Moon.

Interestingly, oxygen is the most abundant element on the Moon. It’s a primary component found in rocks, and this oxygen can be converted to a breathable gas with current technology. A more practical question would be how to best power this process.

Lunar soil is the easiest to mine, it can provide protection from radiation and meteoroids as material for construction. Ice can provide water for radiation shielding, life support, oxygen, and rocket propellant feed stock. Compounds from permanently shadowed craters could provide methane, ammonia, carbon dioxide, and carbon monoxide.

This is just the beginning—as more missions are sent to the Moon, there is more to discover.

Space Faring Humans

NASA plans to land astronauts—one female, one male—to the Moon by 2024 as part of the Artemis 3 mission, and after that, about once each year. It’s the beginning of an unfulfilled promise to make humans a space-faring civilization.

The Moon is just the beginning…the skills learned to map Near-Earth Objects will be the foundation for further exploration and discovery of the universe.

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The Emissions Impact of Coronavirus Lockdowns, As Shown by Satellites

While the COVID-19 pandemic has been all-consuming, these satellite images show its unintended environmental impacts on NO₂ emissions.

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The Emissions Impact of Coronavirus Lockdowns

There’s a high chance you’re reading this while practicing social distancing, or while your corner of the world is under some type of advised or enforced lockdown.

While these are necessary measures to contain the spread of the COVID-19 pandemic, such economic interruption is unprecedented in many ways—resulting in some surprising side effects.

The Evidence is in NO₂ Emissions

Nitrogen dioxide (NO₂) emissions, a major air pollutant, are closely linked to factory output and vehicles operating on the road.

As both industry and transport come to a halt during this pandemic, NO₂ emissions can be a good indicator of global economic activity—and the changes are visible from space.

These images from the Centre for Research on Energy and Clean Air (CREA), as well as satellite footage from NASA and the European Space Agency (ESA), show a drastic decline in NO₂ emissions over recent months, particularly across Italy and China.

NO₂ Emissions Across Italy

In Italy, the number of active COVID-19 cases has surpassed China (including the death toll). Amid emergency actions to lock down the entire nation, everything from schools and shops, to restaurants and even some churches, are closed.

Italy is also an industrial hub, with the sector accounting for nearly 24% of GDP. With many Italians urged to work from home if possible, visible economic activity has dropped considerably.

This 10-day moving average animation (from January 1st—March 11th, 2020) of nitrogen dioxide emissions across Europe clearly demonstrates how the drop in Italy’s economic activity has impacted the environment.


Source: European Space Agency (ESA)

That’s not all: a drop in boat traffic also means that Venice’s canals are clear for the time being, as small fish have begun inhabiting the waterways again. Experts are cautious to note that this does not necessarily mean the water quality is better.

NO₂ Emissions Across China

The emissions changes above China are possibly even more obvious to the eye. China is the world’s most important manufacturing hub and a significant contributor to greenhouse gases globally. But in the month following Lunar New Year (a week-long festival in early February), satellite imagery painted a different picture.

no2 emissions wuhan china
Source: NASA Earth Observatory

NO₂ emissions around the Hubei province, the original epicenter of the virus, steeply dropped as factories were forced to shutter their doors for the time being.

What’s more, there were measurable effects in the decline of other emission types from the drop in coal use during the same time, compared to years prior.

China Coal Use FInal

Back to the Status Quo?

In recent weeks, China has been able to flatten the curve of its total COVID-19 cases. As a result, the government is beginning to ease its restrictions—and it’s clear that social and economic activities are starting to pick back up in March.


Source: European Space Agency (ESA)

With the regular chain of events beginning to resume, it remains to be seen whether NO₂ emissions will rebound right back to their pre-pandemic levels.

This bounce-back effect—which can sometimes reverse any overall drop in emissions—is [called] “revenge pollution”. And in China, it has precedent.

Li Shuo, Senior climate policy advisor, Greenpeace East Asia

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