EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


Atoms and Molecules

August 19, 2021

QuartzCrystals2021e

Photographer: Thomas McGuire

Summary Author: Thomas McGuire

The word atom originated thousands of years ago as a philosophical
idea that there might be a smallest division to every substance. It was
a concept with neither evidence nor application. But, in the early
1800s John Dalton observed that elemental substances combine in
consistent numerical ratios, which provided a scientific basis for the
idea of atoms. Still, this was indirect, non-observable evidence of
atoms. Regardless, Dalton’s discovery led to many useful principles in
chemistry.

There is, however, observational evidence of atoms in minerals.
Each of the characteristic shapes of mineral crystals can be attributed
to the spatial patterns of atoms and molecules. For example, quartz
(SiO ) can form beautiful six-sided crystals because of the way
atoms of silicon and oxygen join in hexagonal patterns, as
shown above in the picture and illustration.

You can also see evidence of irreducible units if you deposit a
small drop of a light, insoluble liquid such as oleic acid (the
principal ingredient of olive oil) on a water surface. The oil will
only spread out to a consistent limiting thickness before it breaks
apart. This experiment has two implications. First, it is more evidence
that there is some kind of irreducible unit of matter.
( Subatomic particles are beyond the scope of these kinds of
observations.) The second is that this is an indication of the diameter
of one of those units even though oleic acid (C H O ) is a
relatively large molecule. For comparison, oleic acid is 10^-9 m
compared to a hydrogen atom which is 10^-11 m.

Related EPODs

Atoms and Molecules Archive - Bonneville Salt Flats Panorama
Mount Etna – Eruption Plume and Scattered Lapilli Willow Falls
Near Hudson, Wisconsin Tower of Silence - Vermilion Cliffs National
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Geology Links

* Earthquakes
* Geologic Time
* Geomagnetism
* General Dictionary of Geology
* Mineral and Locality Database
* Mohs Scale of Mineral Hardness
* This Dynamic Earth
* USGS
* USGS Ask a Geologist
* USGS/NPS Geologic Glossary
* USGS Volcano Hazards Program

-
Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

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EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


Archive - Earth's Shadow in Red Light

September 18, 2021

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Every weekend we present a notable item from our archives.

This EPOD was originally published November 30, 2013.

Photographer: Luis Argerich
Summary Authors: Luis Argerich; Jim Foster

6a01116860210d970c019b00fbd174970c-320wi The photo above shows a
view near Tornquist, Argentina, using a filter sensitive to the 720
nm region (red light) of the electromagnetic spectrum. This is
the far-end of the visible spectrum -- wavelengths are longer here
than in the green or blue portions of the spectrum. The camera is
looking toward the eastern horizon just after sunset. Note the
blue-fringed strip of sky between the two hill slopes at center. This
is known as the Belt of Venus. Our eyes, which utilize the entire
visible spectrum (from about 375-750 nm), sees this band in pinkish
hues. The dark wedge below the Belt of Venus is the edge of night --
the rising Earth's shadow. Healthy vegetation appears white here
since chlorophyll is reflective in red light. The photo at left
shows that, even in winter, the Argentinian plains are always green. It
was taken on July 5, 2013, the same day and at the same location as the
above photo.

Photo details - Inset: Camera Model: Canon EOS 6D; Aperture: f/0.0;
Exposure Time: 0.017 s (1/60); ISO equiv: 1600.
* Tornquist, Argentina Coordinates: -38.071660,-62.008162

Related EPODs

Archive - Earth's Shadow in Red Light Wildfire Smoke Plume Over
Eastern Idaho The Rio Grande Estuary Spirit Lake in the Shadow
of Mount St. Helens Journey to the Center of the World Archive
- Washington, D.C. from Space
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Geography Links

* Atlapedia Online
* CountryReports
* GPS Visualizer
* Holt Rinehart Winston World Atlas
* Mapping Our World
* Perry-Castañeda Library Map Collection
* Types of Land
* World Mapper

-
Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

--- up 2 weeks, 2 days, 21 hours, 55 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)

EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


Odd-Radius Lunar Halos Encircling Jupiter and Saturn

October 19, 2021

PSX_20210825_195952

Photographer: Soumyadeep Mukherjee

Summary Author: Soumyadeep Mukherjee

The halos around the Moon are the odd-radius halos caused
by pyramidal shaped ice crystals, as confirmed by Les Cowley via
EarthSky. These sorts of optical halos are considered to be rarer
than the even radius halos caused by plate or column shaped ice
crystals ( 22° and 46° halos). Also, there are multiple halos
around the moon visible. As a bonus, these halos encircle Jupiter
(on the left of the moon) and Saturn (on the right of the moon) as
the three celestial bodies came for a near-conjunction in the night
sky. These halos appeared for 10 minutes while I was able to capture
them from my home in Kolkata, India. Photo taken on August 21,
2021.

Photo details: Gear: Nikon D5600, Tokina 11-16 atx-i lens, f/4, 8
second exposure, ISO-320, 11mm focal length, Adobe Camera Raw,
Photoshop
* Kolkata, India Coordinates: 22.5726, 88.3639

Related EPODs

Odd-Radius Lunar Halos Encircling Jupiter and Saturn Archive -
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Applied Sciences Links

* BBC: World Water Crisis
* Indoor Air Quality
* Mathematics in Nature
* A Mathematical Nature Walk
* NASA: Applied Earth Sciences
* Remote Sensing Tutorial

-
Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

--- up 6 weeks, 4 days, 21 hours, 55 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)

EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


Green Flash Observed Through Archway of Torre della Meloria

November 19, 2021


MELORIA-raggio-verde2-firmata-Hi

Photographer: Marco Meniero

Summary Author: Marco Meniero

For several years I had hope to be able to take a photo of the
green flash through the archway of the Meloria’s Tower (in
front of Livorno Town Tuscany, Italy). This flash is a wink of
emerald green light that can on occasion be observed just as the Sun
disappears below the horizon. The primary challenge was that I had to
exactly calculate where to stand to capture the last rays of the
setting Sun as it passed through the Tower’s arch. I relied both on my
experience to be able to predict the Sun’s position several tens of
minutes in advance and also on the PhotoPills app, which worked
with extreme precision.

The results are shown above. This photo sequence was captured on the
evening of July 20, 2021. If you look at the tower, at far right,
you'll notice that even though the solar disk itself was nearly
entirely below the horizon, two lateral points remained visible – both
were green. The one on the right can be seen exactly through the Torre
della Meloria.

The tower dates back to 1709. It consists of four pillars joined by
pointed arches on which the body of the tower itself rests on the
surface of the sea in such a way to minimize resistance to waves. It
was on this stretch of the Ligurian Sea in 1284 that a famous
battle took place where the fleet of the Republic of Genoa
overwhelmed that of the Republic of Pisa.

Photo details: Canon Eos1DxMk2, EF 400 IS f / 2.8, closed at f / 5, 200
Iso, solar discs shot with a time of 1/2500, Green flash with a time of
1/1000. Date 07-20-2021
* Livorno Town Tuscany, Italy Coordinates: 43.5485, 10.3106

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Green Flash Observed Through Archway of Torre della Meloria
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Atmospheric Effects Links

* Atmospheric Optics
* Optic Picture of Day: Gruppo Astrofili Galileo Galilei
* Color and Light in Nature
* The Colors of Twillight and Sunset
* Refraction Index
* Image Gallery: Atmospheric Effects
* What is a Rainbow?

-
Earth Science Picture of the Day is a service of the Universities
Space Research Association.

https://epod.usra.edu

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