The Earth Story

If you have clear skies tonight, look up and to the West as Venus will be crossing in front of the Pleiades star cluster. https://solarsystem.nasa.gov/resources/2517/whats-up-video-april-2020-skywatching-tips-from-nasa/

The belt of Venus and our world's shadow Every sunny day around dawn and dusk, the shadow of our planet appears opposite the solar orb, often lined with pink and purple colours. So named because it is the zone where the morning and evenstar appear (since the inner planets are never very far from the sun as seen from earth), it is most clear when the air is dusty and the sky cloud free. The pinks are due to backscattered light off the dust in the atmosphere, at the edge of the world's umbra. In this case, the sun was rising over Lapland, and the ice covered trees formed a beautiful backdrop to a wonderful and common sight, which becomes more awe inspiring when we remind ourselves that we are seeing our planet's shadow extending off towards space. Loz Image credit: Niccolò Bonfadini http://bit.ly/1aWZrAF https://www.yahoo.com/news/photos/arctic-circle-transformed-into-ghostly-world-slideshow/arctic-trees-photo-1343068100.html

What a photo! This spectacular image not only shows the burnt glow of sunset over the African savannah, but also presents the beautiful alignment of Jupiter, Venus and Mercury in the background. Taken by the talented Lóránd Fényes from Hungary. -Jean http://www.cityam.com/1404317760/most-incredible-astronomy-photographs-year

Auroral Australis and treescape Taken by photographer James Garlick from the island of Tasmania off southern Australia, a beautiful spray of multicoloured plasma is glowing in our atmosphere in a 13 second exposure, under the energising influence of particles emitted by the sun. Also visible in the photo is our hellishly hot 'sister' planet, Venus, glimpsed through the tree branches above the horizon towards the right. Loz Image credit: James Garlick https://www.facebook.com/JamesGarlickPhotographer

Let’s look at Venus – REALLY Close!

Sunset

The lake in the foreground is Alikes salt lake, and the land behind it is Kos Island, Greece. If you click on the image and focus, there’s not just a sunset here…you also can make out the movement trails of 3 planets; Jupiter, Venus, and Mercury (left to right), along with a single star, taken in a long series of exposures as the sun set. It’s probably difficult to see those trails if you don’t expand the image, so if you zoom in, thanks and I hope you enjoy.

-JBB

Image credit: Chris K., reproduced here with permission and available here: www.greeksky.gr

Credit to APOD for finding it: http://apod.nasa.gov/apod/ap130613.html

Venus Jupiter Conjunction - right now

Several times each decade Venus and Jupiter appear quite close in the sky, as seen here in this 2009 photo from the European Southern Observatory. This arrangement results from all the planets being in the same plane - as the two objects orbit the sun sometimes they wind up close to on a line with the Earth. This year's conjunction is happening right now, literally - if you have dark sky head out just after sunset and look to the west. This year's conjunction is also special, as these two night lights are as close together in the sky as they will be for the next 40 years.

-JBB

Image credit: ESO http://www.eso.org/public/images/yb_vlt_moon_cnn_cc/

Reference/more information: http://bit.ly/2bzi56W

A tour of night skies around the world. The videographer gives some really neat notes in the caption, excerpted below.

Saturday Night/Sunday morning. Stare at the sun with me. Includes video of the 2012 Venus Transit, likely all taken by the NASA Solar Dynamics Observatory.

Go outside, look up. That’s an order.

Have you been outside in the hours just before sunrise recently? If so, have you looked up and to the East? The sky is putting on an impressive show.

Last week, Commander Mark Kelly tweeted this photo he captured of the start of a sunrise from the International Space Station. Because of the brightness level of the Sun, only a single star appears in the background to my eyes, however three points of light do appear, almost in line.

In order from the top, those 3 points of light are Venus, Jupiter, and Mars. All 3 of them are out right now just before sunrise and Venus in particular has been exceptionally bright over recent weeks. If you’re away from city lights and up at the right time, Mercury can also be visible in this frame, although my area is too bright to spot that tiny rock.

For me, the clocks “fall back” this weekend, so seeing this triple-planet view will require getting up earlier than it does right now. I think a good part of the world already ended summer/daylight savings time, so unfortunately if you haven’t yet caught view of these planets, listening to the instructions in this post will require waking up even earlier. I apologize for that, they don’t let me set the clocks.

-JBB

Image credit: Station CDR Kelly https://twitter.com/StationCDRKel…/status/656451093724069888

Read more: http://bit.ly/1bCuiLi

Awesome... a “solar system to scale” constructed on a dry lake bed in Nevada with full orbits, not just linear distances!

Right Time, Right Place: Earth’s Magnetic Poles

If you were to list factors crucial to life on Earth—water, oxygen, appropriate temperature—magnetism might not make the list. But it should, because without Earth’s magnetic poles, we probably wouldn’t be here. Magnetic poles may be one of the most important things we never think about it.

Let’s meet the two major players in this unique scenario: Earth’s magnetic field and solar winds.

Earth’s magnetic field presents a bit of a mystery at times, but we know its origin has something to do with the iron core. Since the outer core is liquid iron cooling by losing heat, it convects. Convecting, superheated iron under the right conditions can generate a geodynamo —or in simpler words, generate a magnetic field. This magnetic field can be detected anywhere on the planet—thus why a compass points North.

Solar winds are not wind in the typical weather sense; they are beams of ions that stream from the sun. Despite the sun’s immensity, its gravity cannot hold on to some of its more highly charged particles. These particles make their way outwards, sometimes at velocities as fast 500 miles per second.

What happens when the solar winds encounter our magnetic field? Since the winds are made up of charged particles, they get deflected. The magnetic field creates sort of a safety blanket around Earth (called the magnetosphere) that effectively reroutes the sun’s zippy ions.

What would happen if the magnetic field wasn’t there? Again we can look to our planetary neighbors for possible answers. Mars does not have a magnetic field. It also doesn’t have a life-supporting atmosphere. Coincidence? We think not. Many astronomers believe that Mars used to have magnetic poles, but when its core cooled off, the magnetosphere disappeared, along with the atmosphere and any surface water that may have existed.

Solar winds would most likely strip the Earth of its atmosphere if the magnetosphere wasn’t blanketing our beloved planet. In 2008, Mars, Earth, and the sun all happened to fortuitously line up, making it an ideal time for a study regarding solar winds and atmospheres. Research found that Mars lost significantly more oxygen due to solar winds than Earth did, thus making us all a little more grateful for those poles (find the study here--http://bit.ly/1SDNBiU).

There is, however, a possibility that the story isn’t that simple. Venus doesn’t have magnetic poles, either, yet it’s got the thickest atmosphere in the solar system. There is some research, however, that suggests it’s got some sort of induced magnetic field in its upper atmosphere (more about that here—http://bit.ly/1g1VbCn).

Although the connection between magnetosphere, ionosphere, atmosphere and all the other “-spheres” may not be entirely understood, Earth’s magnetic poles appear to be another one of those unique little details that keep us calling it home.

-CM

Photo (a model of Earth’s magnetic field lines) credit: Dr. Gary A. Glatzmaier http://bit.ly/1Ma18Lo For more information: http://bit.ly/1IBswuK http://bit.ly/1SX4no8 http://on.doi.gov/1eRwo2T

Right Time, Right Place: The Greenhouse Effect

This image, released recently by NASA, is the first one of Earth taken at a distance since the famous “Blue Marble” photograph, first published in 1972.

Looking at such pictures really causes me to marvel at how unique our home planet really is. As far as we know, we’re the only the planet with intelligent life, the only planet with active plate tectonics, and the only planet with liquid water on the surface. Are all these things related to each other? Yes indeed.

I wanted to write a few posts about what makes human life on Earth possible. Most often-cited is the fact that we are the right distance from the right size, and while this is very much true it is definitely not the ONLY thing that makes [human] life viable on Earth.

So allow me to introduce Part 1 of this little series: the greenhouse effect.

Are greenhouse gases important to our life on Earth? Yes, absolutely. What’s that I said? Greenhouse gases—the ultimate environmental villain? Yes, as it turns out greenhouse gases in and of themselves are actually not a bad thing. Greenhouse gases, in their recent and current amounts, have been keeping Earth toasty and pleasant. They cause warm air to hug the surface; without them, Earth would be much too cold to live on.

Don’t jump to any conclusions about climate change though—our ideal balance of greenhouse gases has been changing, which could indeed be bad new for us. The effect of greenhouse gases in a planet’s atmosphere is a Goldilocks principle: Too little greenhouse gases=very cold. Too many greenhouse gases=very hot. The right amount=a temperature that is just right.

For some examples of the greenhouse effect gone wrong, we can just look to some other members of our solar system. Take our neighbor, Venus, for example. Venus is by far the hottest planet in the solar system (462 degrees C/864 degrees F) and NOT because it’s closer to the sun. Venus’ atmosphere is super thick and is chock full of carbon dioxide and water vapor—both potent greenhouse gases. A human could not survive on Venus…in fact, solid metals don’t even last that long.

On the other hand, Mars has a very thin atmosphere, and although it’s made up mostly of carbon dioxide, there’s just not enough of it to retain any heat. Consequently, Mars is chilly (-55 degrees Celsius/-67 degrees Fahrenheit).

Earth has achieved a delicate balance—a balance that allows us to live here without getting fried or frozen. Unfortunately, the scales are currently tipping towards having too many greenhouse gases and thus the concern. Preferably, we'd like to keep it the way it is and not go the way of the infernal Venus.

For more unique conditions that enable human life on Earth, stay tuned!

-CM

Photo credit: NASA, read more about it here http://1.usa.gov/1fYuCi5