Strange Paths

The two “Antennae” spiral galaxies started colliding a few hundred million years ago (a short timescale compared to galaxies lifespans). During the collision, the stars pass right on by each other but, because of gravity, enormous tidal forces eject streams of stars on the sides, causing the two-tailed shape of the system. The gas clouds inside each galaxy also get compressed, giving birth to thousands of new stars clusters. The galaxies nuclei will ultimately merge into a single galaxy. A similar event will happen to our Milky Way galaxy, when it will collide with Andromeda in several billion years.

1. © NASA, Hubble Space Telescope, 2006 [↩]

View from Mars Victoria Crater taken by the Opportunity Rover (2006)¹. The sand is rich in reddish iron oxides, which are also suspended as dust in the CO₂ atmosphere, leading to pink-red light scattering. Water ice clouds move at ~10 meters per second and should lead to snowing in some areas.

1. Exaggerated color [↩]
2. © NASA [↩]

Discovery of the W particle at CERN proton-antiproton collider (1982)¹. The proton-antiproton collision creates a W particle which then decays into an high-energy electron, emitted at a wide angle from the beam (indicated by the arrow at the bottom-right) and an invisible neutrino whose presence is deduced by the missing energy of the electron.

1. C. Rubbia. Experimental observation of the intermediate vector bosons W⁺, W^- and Z⁰. Nobel lecture, 8 december 1984 [↩]
2. © CERN [↩]

Observation of the cosmic microwave background by COBE satellite (1990-1993).¹ The cosmic microwave background is a background light in the microwave spectrum (below the infrared), present across all the sky, which was emitted about 14 billion years ago when the universe first became transparent shortly after the big-bang. The irregularities show structure formation in the embryo universe.

1. Nobel Prize 2006 to John C Mather, George F Smoot [↩]
2. © NASA [↩]

Single neuron from the hippocampal region of the brain. Neuron body, axon, and dendritic tree are imaged by using the GFP gene, which express a fluorescent protein in the cell.

1. © Paul De Koninck, Université Laval, Canada [↩]

Night map of earth’s permanent lights by DMSP satellites, showing patterns of urbanization and human activity.

1. © NASA [↩]