s-c-i-guy
s-c-i-guy:

Figure Eights and Peanut Shells: How Stars Move at the Center of the Galaxy
Two months ago astronomers created a new 3D map of stars at the center of our Galaxy (the Milky Way), showing more clearly than ever the bulge at its core. Previous explanations suggested that the stars that form the bulge are in banana-like orbits, but a paper published this week in Monthly Notices of the Royal Astronomical Society suggests that the stars probably move in peanut-shell or figure of eight-shaped orbits instead.
The difference is important; astronomers develop theories of star motions to not only understand how the stars in our galaxy are moving today but also how our galaxy formed and evolves. The Milky Way is shaped like a spiral, with a region of stars at the center known as the “bar,” because of its shape. In the middle of this region, there is a “bulge” that expands out vertically.

s-c-i-guy:

Figure Eights and Peanut Shells: How Stars Move at the Center of the Galaxy

Two months ago astronomers created a new 3D map of stars at the center of our Galaxy (the Milky Way), showing more clearly than ever the bulge at its core. Previous explanations suggested that the stars that form the bulge are in banana-like orbits, but a paper published this week in Monthly Notices of the Royal Astronomical Society suggests that the stars probably move in peanut-shell or figure of eight-shaped orbits instead.

The difference is important; astronomers develop theories of star motions to not only understand how the stars in our galaxy are moving today but also how our galaxy formed and evolves. The Milky Way is shaped like a spiral, with a region of stars at the center known as the “bar,” because of its shape. In the middle of this region, there is a “bulge” that expands out vertically.

the-science-llama

the-science-llama:

The color of the Aurora depends on the altitude and the atom being struck by solar radiation (causing excitation). At higher altitudes, there is more Atomic Oxygen than Nitrogen, leading to the common color stratifications you see.

500-200 km altitude
— Atomic Oxygen — Red
200-100 km
— Atomic Oxygen — Greenish-Yellow
— Ionized Nitrogen — Blue/Purple
100-80 km
— Nitrogen (N2) — Crimson

Oxygen only emits red at higher altitudes because once it’s excited, it takes a longer time to emit red than it does green. Why is that important? Well, at lower altitudes there is more Nitrogen for the Oxygen to bump into and absorb that excitation-energy before it gets a chance to emit red light. In this case, where the collision occurs, the Oxygen will emit Green and at low enough altitudes the Nitrogen-Oxygen collisions eventually prevent Oxygen from emitting any light at all.

During stronger storms, high energy solar particles will reach lower in the atmosphere and cause the Crimson emission from Nitrogen, creating a deep-red band at the lower edge of the aurora. Other elements emit light too, like Hydrogen (Blue) or Helium (Purple) which are at higher altitudes.

Sources and further reading:
WebExhibits
ExploratoriumWindow2UniverseWikiGif source

Let’s go to alaska@

seafarers-deactivated20131211

seafarers:

Mount Nyiragongo is a stratovolcano in the Virunga Mountains associated with the Albertine Rift. It is located inside Virunga National Park in the Democratic Republic of the Congo.  The main crater is about two km wide and usually contains a lava lake. The crater presently has two distinct cooled lava benches within the crater walls - one at about 3175m (10,400 ft) and a lower one at about 2975 m (9800 ft). Nyiragongo’s lava lake has at times been the most voluminous known lava lake in recent history. Nyiragongo and nearby Nyamuragira are together responsible for 40% of Africa’s historical volcanic eruptions.

by Michel and Anne-Marie Detay

Volcano!!!