NASA astronaut Don Pettit recently uploaded a gallery of photos to the Johnson Space Center’s Flickr page. Pettit on how he captured these amazing images:
“My star trail images are made by taking a time exposure of about 10 to 15 minutes. However, with modern digital cameras, 30 seconds is about the longest exposure possible, due to electronic detector noise effectively snowing out the image. To achieve the longer exposures I do what many amateur astronomers do. I take multiple 30-second exposures, the ‘stack’ them using imaging software, thus producing the longer exposure.”
Ed note: Here are the Hubble Space Telescope’s finest photos.
h/t Twisted Sifter
Whooooooooooa. Thank you, Don. These are phenomenal!
Incredible close-up photos of animals’ eyes by Suren Manvelyan
“The Black Death” usually invokes mental images of tolling church bells, doctors with beak-shaped masks, necrotic tissue, grave diggers, and the Middle Ages - but that’s far from the whole story.
Meet Yersinia pestis: A Gram-negative, rod-shaped bacterium pictured here (in green) using scanning electron micrography on proventricular spines of a Xenopsylla cheopis flea (in purple). Yersinia pestis, which can infect most small mammals - cats, rats, dogs, and humans among them - is the cause of the bubonic, pneumonic, and septicemic plague. While we may now know that the Black Death was not caused by bad smells, as was once believed, Yersinia pestis has proven extraordinarily persistent - and resistant to eradication.
Because of the zoonotic relationship between Y. pestis, humans, fleas, and rats, the best we can do, to date, is contain outbreaks of the plague when they arise. Most recently, they’ve arisen in China, Peru, and the United States. While the spread of infection is quickly stopped and antibiotic treatment is effective, individual cases of the plague are often not isolated quickly enough, as was the case in China; early symptoms are general and include high fever, coughing, dizziness and vomiting, and resemble those of the flu. Don’t be fooled, though, infection with Y. pestis is still as deadly as ever: The index case in the Chinese outbreak died, and the septicemic plague (thankfully, the rarest form of the disease, caused when the bacterium enters the bloodstream directly), kills within 24 hours.
Image Credit: NIAID (National Institute of Allergy and Infectious Disease).
I have a problem that hurts my friends. It breaks their trust. It makes them think I am playing jokes at their expense.
Yes readers, I am chilli immune. For the most part, it doesn’t register for me. My friends ask me if a dish is spicy and invariably I say its not. I have one friend in particular who is so chilli-phobic that even the slightest hint of chilli sends her running for the water jug (needless to say, she has now started to get a second opinion on the spice level!). But we were both bought up eating modern Australian food, with Thai, Indian and Mexican influences so why the difference in reaction?
I have a theory: my dad used to play with me called ‘give you a dollar’ in which he would challenge me to eat something like a whole chilli or a tablespoon of lemon juice. As a pretty adventurous eater, these games kept me in canteen money for most of my childhood. Does this mean I have been ‘trained’ to tolerate chilli?
Let’s start why chillies are hot - they don’t want to be eaten! They produce a chemical called capsaicin to deter those curious enough to taste them from taking a second bite. The heat of chillies is measured in Scovilles according to the amount of capsaicin they contain. To give you an idea of the scale, a capsicum sits at zero, Jalapenos range between 2500 – 8000, Habaneros range 350000 – 577000, pepper spray is between 2- and 5.3 million and pure capsaicin is 15 million. The hottest naturally occurring chilli is the Trinidad Moruga Scorpion chilli with a Scoville scale rating of 2 million! Even I wouldn’t go anywhere near that!
So if you are possessed to bite into a Trinidad Moruga Scorpion chilli what should you do? Running for the bottle of water as my friend often does won’t work. You’d best order a delicious mango lassi or a glass of milk. Capsaicin is hydrophobic and won’t dissolve in water, but it will dissolve in something fatty, like full cream milk or yoghurt.
When capsaicin comes in contact with receptors on the tongue, it opens the cell up to ions causing it to signal a heat or pain sensation to the brain. When the signal reaches the brain, neurotransmitters pass the message along by releasing chemicals into the synaptic gap, which tells the next neurotransmitter there is ‘heat’ on the tongue. This passing of information continues until it reaches the sensory cortex where the message is decoded and you become consciously aware of the heat/pain sensation on the tongue.
The thing is, there is a finite amount of these signaling chemicals in the neurotransmitters, so if you use all the chemicals up in one meal, there are less to signal the heat in the next meal. It takes some time to restock these chemicals, so if your diet is high in chilli, you can build up a tolerance, simply because your neurotransmitters can’t pass the messages along anymore. So my Dad’s ‘bet you a dollar game’ and my continued use of chilli in my cooking means that my brain doesn’t pass the heat/pain messages along as much as my friends brain does.
So the moral of the story is don’t trust anybody when it comes to chilli. You never know how many neurotransmitter chemicals that person has to pass along the message!
The Incredible Eye
The eye stands as a testament to the effectiveness and magnitude of what can be achieved through natural selection. These extraordinary false-colour SEM images of the human eye were the brainchild of Professor Pietro Motta at the Institute of Human Anatomy of the University La Sapienza in Rome.
Top Left: Surface cells on the iris of the eye. Pigment cells (melanocytes, blue and brown) can be seen here, joined loosely together by connective tissue fibres (white). Smaller macrophage cells dot the surface.
Top Right: Lens of the eye. Lens cells run diagonally (dark green) across this field of view. The transparency of the lens (width 4 millimetres) is due to the absence of nuclei in these cells, and to the crystalline precision of their arrangement.
Centre: The inner surfaces of the iris and adjoining structures in the human eye. At far right (blue) is the edge of the pupil, the hole that allows light into the eye. Coloured mauve is the iris which controls the size of the pupil and therefore how much light will enter. The band of folds down the centre (red) are the ciliary processes.
Bottom left: The surface of the cornea. The matrix- like pattern (seen here) consists of individual flattened transparent cells. This is a stratified squamous epithelium which is 5 cell layers deep. Although full of nerves, there are no blood vessels in the cornea.
Bottom right: The human retina featuring the central fovea, a crater-like depression in the photosensitive layer of the eye. The foveal retina is the area of greatest visual acuity and contains only cone receptor cells. When an eye looks at an object, that part focused on the fovea is the portion most accurately registered by the brain.
All image credit goes to Professor Pietro Motta and Science Photo Library.