New Images of the Massive Iceberg That Broke Off From Antarctica This Summer

NASA/Nathan Kurtz
NASA/Nathan Kurtz

This summer, a massive crack finally broke apart Antarctica’s Larsen C ice shelf, creating one of the world’s largest icebergs, called A-68. NASA has taken plenty of satellite images of the area, but now, thanks to flights by the agency’s Operation IceBridge, we have close-ups too, as The Washington Post reports.

Operation IceBridge is NASA’s project to survey and map the status of polar ice via plane. The project is running several survey missions out of Argentina and from scientific bases at the South Pole this fall, using gravimeters, magnetometers, and other sensors to measure changes in polar ice. They have taken a few flights so far that passed over Larsen C, the most recent leaving from Ushuaia, Argentina, on November 12.

The sheer edge of A-68 leads into blue ocean
The edge of A-68
NASA/Nathan Kurtz

Aerial IceBridge photos taken in the last few weeks show the massive size of the ice shelf and the iceberg it calved this summer. "Most icebergs I have seen appear relatively small and blocky, and the entire part of the berg that rises above the ocean surface is visible at once,” Kathryn Hansen, a member of NASA’s news team, wrote on NASA’s Earth Observatory blog after seeing A-68 for herself on the most recent IceBridge flight. “Not this berg. A-68 is so expansive it appears [as] if it were still part of the ice shelf.”

NASA tweeted out these incredible images from IceBridge's October 31 flight earlier this month.

An aerial photo of an ice shelf and the iceberg it calved
The ice on the left is the Larsen C ice shelf; the right, the western edge of A-68.
NASA/Nathan Kurtz

An aerial view of sea ice, blue water, and the edge of iceberg A68
A view across sea ice toward A-68
NASA/Nathan Kurtz

The November 12 flight was aimed at mapping the bedrock below the polar ice with NASA’s gravimeter, but the scientists still have more research planned. Additional IceBridge flights will be leaving from Antarctica later this month, collecting data with different instruments than the flights that left out of Argentina.

[h/t The Washington Post]

Does Sound Travel Faster or Slower in Space?

iStock/BlackJack3D
iStock/BlackJack3D

Viktor T. Toth:

It is often said that sound doesn’t travel in space. And it is true … in empty space. Sound is pressure waves, that is, propagating changes in pressure. In the absence of pressure, there can be no pressure waves, so there is no sound.

But space is is not completely empty and not completely devoid of pressure. Hence, it carries sound. But not in a manner that would match our everyday experience.

For instance, if you were to put a speaker in interstellar space, its membrane may be moving back and forth, but it would be exceedingly rare for it to hit even a single atom or molecule. Hence, it would fail to transfer any noticeable sound energy to the thin interstellar medium. Even the somewhat denser interplanetary medium is too rarefied for sound to transfer efficiently from human scale objects; this is why astronauts cannot yell to each other during spacewalks. And just as it is impossible to transfer normal sound energy to this medium, it will also not transmit it efficiently, since its atoms and molecules are too far apart, and they just don’t bounce into each other that often. Any “normal” sound is attenuated to nothingness.

However, if you were to make your speaker a million times bigger, and let its membrane move a million times more slowly, it would be able to transfer sound energy more efficiently even to that thin medium. And that energy would propagate in the form of (tiny) changes in the (already very tiny) pressure of the interstellar medium, i.e., it would be sound.

So yes, sound can travel in the intergalactic, interstellar, interplanetary medium, and very, very low frequency sound (many octaves below anything you could possibly hear) plays an important role in the formation of structures (galaxies, solar systems). In fact, this is the mechanism through which a contracting cloud of gas can shed its excess kinetic energy and turn into something compact, such as a star.

How fast do such sounds travel, you ask? Why, there is no set speed. The general rule is that for a so-called perfect fluid (a medium that is characterized by its density and pressure, but has no viscosity or stresses) the square of the speed of sound is the ratio of the medium’s pressure to its energy density. The speed of sound, therefore, can be anything between 0 (for a pressureless medium, which does not carry sound) to the speed of light divided by the square root of three (for a very hot, so-called ultrarelativistic gas).

This post originally appeared on Quora. Click here to view.

How Fossil Fuel Use Is Making Carbon Dating Less Accurate

iStock.com/Harry Wedzinga
iStock.com/Harry Wedzinga

The scientific process of carbon dating has been used to determine the age of Ötzi the Iceman, seeds found in King Tutankhamun’s tomb, and many other archaeological finds under 60,000 years old. However, as SciShow points out in a recent episode, the excessive use of fossil fuels is making that method less reliable.

Carbon dating, also called radiocarbon or C-14 dating, involves analyzing the ratio of two isotopes of carbon: C-14 (a radioactive form of carbon that decays over time) and C-12 (a more stable form). By analyzing that ratio in a given object compared to a living organism, archaeologists, paleontologists, and other scientists can get a pretty clear idea of how old that first object is. However, as more and more fossil fuels are burned, more carbon dioxide is released into the environment. In turn, this releases more of another isotope, called C-12, which changes the ratio of carbon isotopes in the atmosphere and skews the carbon dating analysis. This phenomenon is called the Suess effect, and it’s been well-documented since the ‘70s. SciShow notes that the atmospheric carbon ratio has changed in the past, but it wasn’t anything drastic.

A recent study published in Nature Communications demonstrates the concept. Writing in The Conversation, the study authors suggest that volcanoes “can lie about their age." Ancient volcanic eruptions can be dated by comparing the “wiggly trace” of C-14 found in trees killed in the eruption to the reference "wiggle" of C-14 in the atmosphere. (This process is actually called wiggle-match dating.) But this method “is not valid if carbon dioxide gas from the volcano is affecting a tree’s version of the wiggle,” researchers write.

According to another paper cited by SciShow, we're adding so much C-12 to the atmosphere at the current rate of fossil fuel usage that by 2050 brand-new materials will seem like they're 1000 years old. Some scientists have suggested that levels of C-13 (a more stable isotope) be taken into account while doing carbon dating, but that’s only a stopgap measure. The real challenge will be to reduce our dependence on fossil fuels.

For more on how radiocarbon dating is becoming less predictable, check out SciShow’s video below.

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