Category: Planet Earth

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Solar System Astronomy Life on Earth Planet Earth Prehistoric

What are the Differences Between a Meteoroid, a Meteor, a Meteorite, an Asteroid, and a Comet? [Explained]

Two asteroids passing Earth
Two Near-Earth Objects (in this case, two asteroids) passing Earth. An ESA image, published in the "Space in Images" series by the European Space Agency. A near-Earth object (NEO) is any small Solar System body whose orbit can bring it into proximity with Earth. By definition, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU, roughly the distance between the Earth and the Sun, which was defined exactly as 149,597,870,700 meters or about 150 million kilometers or 93 million miles since 2012). If a NEO's orbit crosses the Earth's and the object is larger than 140 meters (460 ft) across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids.

Hint: they are all space rocks. But, there are some differences. The biggest difference between an asteroid and a comet, for example, is what they are made of.

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Earth from Space Places Space Exploration

Mont Saint-Michel, France, From Space

Mont Saint-Michel from space (cropped)
Lying between Brittany to the west and Normandy to the east, this remarkable bay, which is listed as a UNESCO world heritage site, sees some of the biggest tides in continental Europe. There can be up to 15 m difference between low and high water. When spring tides peak, the sea recedes about 15 km from the coast and when it returns it does so very quickly, making it a dangerous place to be. Sentinel-2 captured this image when the tide was out so that the vast area of sand dunes is exposed cut by meandering channels of shallow water. Three rivers empty into the bay: the Couesnon, the Sée and the Sélune. The famous rocky islet of Mont Saint-Michel, visible as a small dark spot in the south of the bay, is about 1 km from the mouth of the Couesnon. Home to a Benedictine monastery and village, Mont Saint-Michel is also a UNESCO world heritage site and a mecca for tourists. The bay, however, has been prone to silting up in the last couple of centuries. Actions by man, including farming and the building of a causeway to the island monastery, have added to this problem. A major campaign has ensured that Mont-Saint-Michel preserves its maritime character and remains an island. The main river into the bay, the Couesnon, for example, is being left to flow more freely so that sediments are washed out to sea. This is a cropped image. You can see the full-size image at: ESA - Space in Images

The European Space Agency (ESA) occasionally posts high-resolution photos of space under the title of “week in images”. This amazing image of the Mont Saint-Michel from space, which was captured on 21 June 2017, is also featured on the ESA’s Earth from Space video programme, presented by Kelsea Brennan-Wessels from the ESA Web-TV virtual studios.

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Global Warming Animals Climate Insects Life on Earth Plants

Most species hold their geographic range if we limit global warming to 1.5°C [new study]

A bird on a tree.
A bird on a tree. Image: Bernd Thaller, PXHere

If we limit global warming to 1.5°C rather than 2°C above the pre-industrial levels by the year 2100, the impacts of climate change would be much less dramatic, a new study says. According to the researchers, for vertebrates and plants, the number of species losing more than half their geographic range by 2100 will be halved when warming is limited to 1.5°C, compared with projected losses at 2°C. It would be even better for insects, the most diverse group of animals on Earth: the number is reduced by two-thirds.

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Animals Life on Earth

Endangered animals more likely to get donated if they’re cute, study says

A white lion cub
A white lion cub. White lion cubs exist, but they are rare. Because they can be born only if both parents possess a recessive mutation in a gene that makes colored pigments called melanins. 17 births have been recorded in five different prides between 2007 and 2015. On March 5, 2018, a white lion cub has been seen at the Ngala Private Game Reserve in South Africa. Technically, these animals are considered leucistic, not albino, because they have some pigment in certain areas, such as the eyes. White lions are also exceptionally rare to see fully grown in the wild; most of the white lion cubs don't reach adulthood. A lion's usual tawny color helps it blend into tall grasses and other vegetation. The animals also hunt at night, when a white lion would stand out even more.

43% of Americans would be more likely to donate to an endangered animal if it was cute, according to a study titled “Selective Sympathy: Comparing Sentiment Toward the Appearance of Endangered Species” published by African Wildlife Foundation (AWF). A team at AWF has surveyed 1k Americans on how much they know about wildlife conservation, and how much they’re willing to open their wallets to help endangered animals. Here’s what they found.

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Astronomy Planet Earth

TRAPPIST-1e has an Iron Core

TRAPPIST-1e artist conception
An artist's conception of TRAPPIST-1e, an exoplanet orbiting its star TRAPPIST-1 in the habitable zone. TRAPPIST-1, also designated as 2MASS J23062928-0502285, is an ultra-cool red dwarf star located 39.6 light-years (12.1 pc) from the Sun. It is slightly larger but much more massive than the planet Jupiter. In this artist's depiction, TRAPPIST-1e shown covered in water with ice caps on the night side (all seven planets of the TRAPPIST-1 system are likely to be tidally locked, which means one side of each planet permanently facing the star, making the development of life there "much more challenging"). TRAPPIST-1e has a slightly higher density than Earth, indicating a terrestrial rock and iron composition.

A new study published on April 26, 2018, suggests that TRAPPIST-1e, an exoplanet orbiting the red dwarf star TRAPPIST-1, has a large iron core. This could mean that the planet TRAPPIST-1e may have a protective magnetosphere (see notes 1) as we have here on Earth.

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Climate Astronomy Planet Earth

What would happen if the Earth started spinning backward?

The Blue Marble
In December 1972, Apollo 17 spacecraft took a photo of Earth from space, at a distance of about 45,000 kilometers (28,000 miles). This image, with the official NASA designation AS17-148-22727, became known as "The Blue Marble", one of the most iconic photos of Earth from space. In fact, it was not the first clear image of Earth taken from space - similar photos had already been taken as early as 1967. But, the 1970s were the scene of a big surge in environmental activism. For example, on April 22, 1970, the first "Earth Day" was organized by Gaylord Nelson, former senator of Wisconsin, and Denis Hayes, a Harvard graduate student. Millions of people gather in the United States for the event. So, in today's terms, image AS17-148-22727 went "viral" and became a symbol of the environmental movement, as a depiction of Earth's frailty, vulnerability, and isolation amid the vast expanse of space. According to NASA archivist Mike Gentry, it is among the most widely distributed images in human history.

The dynamics of the ocean and the atmosphere are strongly influenced by the Earth’s rotation. Currently, our planet rotates from west to east (prograde, which appears counterclockwise) with a linear velocity of 465.1013 m/s (1674.365 km/h or 1040.40 mph) at the equator. What would happen if the Earth started spinning backward (from east to west)?

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Planet Earth Life on Earth Plants

Earth’s Biosphere from space [The Green Marble]

Earth greenness in May
Earth's greenness during the month of May.

NASA has published a video titled “Earth’s Biosphere: The Green Marble”, showing the monthly averages of land greenness (vegetation) and ocean chlorophyll. You can watch how the primary producers (plants and phytoplankton) transform the Earth’s landmasses and oceans over 12 months.

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Earth from Space Geology Space Exploration

Kliuchevskoi Volcano from Space (NASA Image)

Kliuchevskoi Volcano, 1994. NASA image (sts068-218-007)
STS068-218-007 (30 September-11 October 1994) - (Kliuchevskoi Volcano) The crewmembers used a 70mm camera to photograph this northeasterly looking view of the plume from the Kamchatka peninsula's newly erupted volcano. The eruption was photographed from 115 nautical miles above Earth. Six NASA astronauts spent a week and a half aboard the Space Shuttle Endeavour in support of the Space Radar Laboratory 2 (SRL-2) mission. This is a resized image. You can see the full-size image on NASA Spaceflight website.

During the STS-68 mission (September 30-October 11, 1994), the crew members of Space Shuttle Endeavour used a 70 mm camera to photograph Klyuchevskaya Sopka (also known as Kliuchevskoi), a stratovolcano, the highest mountain on the Kamchatka Peninsula of Russia and the highest active volcano of Eurasia. The eruption was new when this photo was taken. It was photographed from 115 nautical miles (213 kilometers) above Earth.

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Prehistoric Animals Evolution Geography Geology Insects Life on Earth Planet Earth Plants

Here’s What did Ancient Earth Look Like

Ancient Earth (280 million years ago)
Ancient Earth (280 million years ago). Permian period. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the Russian city of Perm. The Permian witnessed the diversification of the early amniotes into the ancestral groups of the mammals, turtles, lepidosaurs, and archosaurs. The world at the time was dominated by two continents known as Pangaea and Siberia, surrounded by a global ocean called Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. Amniotes, who could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors. Extreme conditions such as polar ice caps and deserts limited the extent of plant life, but amphibious tetrapods and reptiles diversified where plants grew. Oceans teemed with fish and invertebrate life.

I stumbled upon an amazing web page showing what did ancient Earth look like. On the “Dinosaur Pictures and Facts” web page (dinosaurpictures.org), there’s also an interactive animation. On this page, you can either select the years (i.e. 600 million years ago) or jump to a particular event (i.e. first multicellular life) and see how ancient Earth did look like then. You can also remove the clouds and stop the Earth’s rotation if you want to.

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Climate Life on Earth Places Plants

Iceland is growing new forests for the first time in 1,000 years

Screenshot: Iceland growing forests
Iceland was extensively forested when it was first settled. When the Vikings first arrived in the 9th century, the Nordic island was covered in 25 to 40 percent forest, compared to 1% in the present day. In the late 12th century, Ari the Wise (Ari Thorgilsson, 1067–1148 AD), Iceland’s most prominent medieval chronicler, described it in the Íslendingabók (Book of IcelandersNotes 1) as “forested from mountain to sea shore”. Unfortunately, after the permanent human settlement, the forests were heavily exploited for firewood, timber and to make room for farming. Within a few centuries, almost all of Iceland’s trees were gone. This rapid deforestation has resulted in massive soil erosion that puts the island at risk for desertification. Today, many farms have been abandoned. Three-quarters of Iceland’s 100,000 km2is affected by soil erosion, 18,000 km2 (6,900 sq mi) serious enough to make the land useless. But,, with the help of forestry societies and forest farmers, Iceland's trees are slowly beginning to make a comeback.

Iceland was extensively forested when it was first settled. When the Vikings first arrived in the 9th century, the Nordic island was covered in 25 to 40 percent forest, compared to 1% in the present day. In the late 12th century, Ari the Wise (Ari Thorgilsson, 1067-1148 AD), Iceland’s most prominent medieval chronicler, described it in the Íslendingabók (Book of Icelanders (see notes 1) as “forested from mountain to seashore”.

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