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“You are an aperture through which the universe is looking at and exploring itself.”
― Alan Wilson Watts

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the-actual-universe:

NGC 1232 AND THE GRAND DESIGN

The term “grand design spiral galaxy” is merely a classification, a method of categorizing a galaxy’s structure, but the lofty language accurately captures the majestic appearance of such galaxies.

Grand design spirals, like NGC 1232 shown here, only account for about 10% of all known spiral galaxies, and yet they are iconic. When imagining a galaxy, the perfect spiral shape and clearly-defined arms are common imagery, even though more tightly-wound flocculent spirals or less-defined spirals are far more common. 

Perhaps our preference for the perfect spiral is an instinctive aesthetic. The famous Fibonacci spiral, after all, is found throughout nature, occurring in everything from plant structure to the proportions of the human body [Read more about Fibonacci’s sequence here]. There is a certain pleasing symmetry to the pervasiveness of Fibonacci spirals, and our eyes find them easy to follow. 

Galaxies such as NGC 1232, located 60 million light-years away in Eridanus, surely have no regard for our aesthetic preferences. Their beautiful arrangements are a natural consequence of physics.

So how do these galaxies get their arms? It’s easy to visualize solid body rotation, or the rotation of points along a flat plane as they are drawn in toward the center. The same phenomenon happens as you watch water circle the shower drain. The problem, however, is that if galaxies followed this pattern, their arms would be tightly wound at a fast rate, and we wouldn’t see such beautiful spirals. This is known as the “winding problem.” Given the mass at the center of a galaxy, it is just not possible that such clearly-defined spiral arms are just stars in a simple orbit around the center.

In the 1960s, scientists C.C. Lin and Frank Shu proposed the density wave theory, which posits that the gravitational interaction between stars and other matter in the galaxy prevents the so-called winding problem. The idea is that the arms are not actually a result of matter, but rather of varying density.

The theory can be compared to a traffic jam. As cars get backed up on the highway, the density of the traffic jam will increase as more cars move toward the center of the jam in an attempt to get to areas of lower density. The location of an individual car might change, but the overall density of the traffic jam does not go through any significant changes Similarly, the stars and other matter that make up NGC 1232’s arms may be pulled along by gravity, but they are moving through the density waves that make up the arms.

Newer research suggests that even this explanation is too simple. Even when accounting for density waves, the longevity of these spiral arms still isn’t quite explained. In 2011, researchers examined 12 nearby spiral galaxies in order to test the density wave theory. If Lin and Shu’s theory was correct, the researchers expected to find a progressive variation in areas of star formation. Instead, the three different phases of star formation they were looking for were scattered throughout the arm. This led to two possible conclusions: either the spiral arms repeatedly dissipate and reform, or the density waves contain variations in pattern speeds that would muddle the areas of star formation. 

Ultimately, it is a question that will be settled by more sophisticated modeling processes and increased research. Though the designs of galaxies like NGC 1232 are pleasantly simple, it’s clear that the same can’t be said for the mechanisms by which they form.

-RLO

Image: FORS8.2-meter VLT AntuESO

Sources: 1, 2, 3, 4

blackpowerisforblackmen:

Lupita was recently named the most beautiful by People’s Magazine, and some of their readers expressed their dissatisfaction with this decision  in the comment section. One reader even commented that Lupita didn’t deserve this title because she’s 100% black(she finds women unattractive if they’re 100% black). These comments made me think of the brilliant post made by radicalrebellion

White women (non-black women of color included in this as well) become offended and angry when a black woman (especially a dark skinned black woman like Lupita) is depicted as beautiful and worthy of appreciation because it jeopardizes their position as the epitome of beauty and womanhood. Black women are viewed as the antithesis of White beauty and womanhood, these white women are completely apathetic and silent when dark skinned Black women are portrayed as “ugly” and “unlovable” by the mainstream media because they benefit from this oppression. That’s why you never see white supermodels discussing racism and colorism in the fashion industry. However, these readers wouldn’t complain if it were light skinned black women like Halle Berry, Beyonce, or Rihanna (we all know why, hint: colorism). Anyway, congratulations to the ***flawless Lupita for being named the most beautiful!  

aljazeeraamerica:

Boko Haram’s roots in Nigeria long predate the al-Qaeda era 

The bomb blast near Abuja, Nigeria, on April 14 that killed at least 75 people, and the kidnapping the following day of what appeared to be more than 100 schoolgirls in the northeastern Nigerian town of Chibok, have placed Boko Haram firmly at the top of local news. Security was tight in Abuja’s churches and cathedrals over the Easter weekend, and in a video released to Agence France-Presse on Sunday, Boko Haram leader Abubakar Shekau claimed responsibility for the bomb, warning, “We are in your city, but you don’t know where we are.” 

But northeastern Nigeria had been bandit country long before the emergence of Boko Haram. And while it may coincide with the growth over the past two decades of Salafist armed groups elsewhere in the region and beyond, the real context for Boko Haram’s emergence is the long political and economic decline of Nigeria’s northeast and enduring Kanuri opposition to northern power structures.

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