What Is The Hottest Place on Earth?

What Is The Hottest Place on Earth?

We’ve talked about Venus, the hottest planet in the Solar System, but we know things can get pretty hot here on Earth, too. You may be wondering, where on the surface of the Earth has the highest natural temperature been recorded?

The location of this world record has had some controversy, but as of 2013, the hottest spot on record was the Furnace Creek Ranch in California’s Death Valley. On July 10, 1913, weather instruments measured 56.7 degrees Celsius, or 134 degrees Fahrenheit.
The previous record of 56 degrees at El Azizia, Libya was overturned because a systematic study in 2012 discovered there were errors in the measuring methods.

Similar temperatures to Death Valley’s record have been recorded around the World:
55 degrees in Africa,
53.6 in Asia,
50.7 in Australia,
and 49.1 in Argentina.

But these are just measurements from weather stations. It’s likely there are hotter temperatures, but nobody was around to measure. NASA satellites have spotted regions in Iran’s Lut desert which might have reached 70 degrees Celsius during the summers of 2004 and 2005.

So that’d be the hottest spot on the surface, but what about the hottest natural spot anywhere in the entire planet? Now you’ve got to travel straight down 6,371 kilometers to the very center of the Earth. At the inner core, the temperatures rise to about 5,430 degrees C, or 5700 Kelvin. Amazingly, this is about the same temperature as the surface of the Sun.

Some of this high temperature comes from leftover heat from the formation of the planet, 4.54 billion years ago, but the vast majority comes from the decay of radioactive minerals inside the Earth. It was likely hotter in the past, but all the short-period isotopes have already been depleted.

I keep saying the word “natural”, but what about “unnatural”? Wondering about the hottest temperature EVER generated on Earth? Thermonuclear explosions reach temperatures of tens of millions of Kelvin. Fusion experiments have hit 500 million Kelvin. But that’s nothing.

In 2012, physicists working with the Large Hadron Collider were investigating the conditions that might have existed during the earliest moments of the Big Bang.
They generated a quark gluon plasma that had a temperature of 5.5 trillion Kelvin.
Unless aliens can do better, this is not only the hottest temperature ever recorded on Earth, it’s easily the hottest temperature anywhere in the Universe since the Big Bang itself.

Astronomy Cast 319: The Zodiac

Although the Zodiac is best known for astrology nonsense, it has a purpose in astronomy too. The constellations of the Zodiac define the plane of the ecliptic: the region where the Sun, Moon and planets appear to travel through the sky. What are the constellations of the Zodiac, and how do astronomers use them as way points?

We record Astronomy Cast as a live Google+ Hangout on Air every Monday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.

How Far is Earth from the Sun?

How Far is Earth from the Sun?

It’s amazing to think that for the majority of human history, we had almost no understanding about the Sun. We didn’t know what it was made of, how it formed, or how it produced energy. We didn’t know how big it was, and we didn’t know how far away it was.

We orbit the Sun at a distance of about 150 million kilometers. This number is actually an average, since we follow an elliptical path. At its closest point, the Earth gets to 147 million km, and at its most distant point, it’s 152 million km.

Distances in the Solar System are so vast that astronomers use this distance as a standard for measurement, and so the average distance from the Earth to the Sun is called an astronomical unit. Instead of saying that Pluto is 5.87 billion kilometers away from the Sun, astronomers say that it’s 39 astronomical units, or AUs.

You might be surprised to know that the distance from the Sun to the Earth was only determined within the last few hundred years. There were just too many variables. If astronomers knew how big it was, they could figure out how far away it was, or vice versa, but both of these numbers were mysteries.

Ancient astronomers, especially the Greeks, tried estimating the distance to the Sun in several different ways: measuring the length of shadows on Earth, or comparing the size of the Moon and its orbit to the Sun. Unfortunately, their estimates were off at least by a factor of 10.

The key to figuring out the distance to the Sun came from observing Venus as it passed directly in front of the Sun. This rare event, known as a Transit of Venus, happens only twice every 108 years. Once devised, the best opportunities for taking this precise measurement came during the Venus transits of 1761 and 1769. Astronomers were dispatched to remote corners of the globe to observe the precise moment when Venus began to move in front of the Sun, and when it had moved completely across the surface.

By comparing these measurements, astronomers could use geometry to calculate exactly how far away the Sun is. Their initial calculations put the distance at 24,000 times the radius of the Earth. Not bad considering our modern measurement of 23,455 times the radius of the Earth.

Modern astronomers can use radar and laser pulses to calculate the distance to objects in the Solar System. For example, they fire an intense beam of radio waves at a distant object, like Mercury, and then calculate how long it takes for the waves to bounce off the planet and return to Earth. Since the speed of light is well known, the return travel time tells you how far away the planet is.

Astronomy has truly helped us find our place in the Universe. It nice to be living in a time when many of these big mysteries have been solved. I don’t know about you, but I can’t wait to see what’s around the corner of the next discovery.

Weekly Space Hangout – October 25, 2013: Preventing Asteroids, More Comets, Worldview Balloon

So much space news, so little time. We had a great Weekly Space Hangout with several of our familiar space journalist friends. No huge stories, but lots of interesting tidbits, about asteroid protection, balloon trips to the edge of space, and the discovery of the furthest galaxy.

Host: Fraser Cain

Panel: Alan Boyle, Amy Shira Teitel, David Dickinson, Nancy Atkinson, Elizabeth Howell

Stories:
Preventing Asteroid Strikes
Japanese Asteroid Cannon
How to see Other Comets
Furthest Galaxy Found
More than 1000 Exoplanets
Worldview Balloon Flights
Watch the Sun Split Apart
What’s the Weather on Titan
Spider Adapts to Return to Gravity
ExoMars Rover

We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Google+, Universe Today, or the Universe Today YouTube page.

How Many Satellites are in Space?

How Many Satellites are in Space?

The space age began on October 4, 1957 with the launch of the first artificial satellite, Sputnik 1. This tiny spacecraft lasted only three months in orbit, finally burning up in the Earth’s atmosphere.

Following in these historic footsteps, many more spacecraft have been sent into Earth’s orbit, around the Moon, the Sun, the other planets, and even out of the Solar System itself. At the time that I’m recording this video, there are 1071 operational satellites in orbit around the Earth. 50 percent of which were launched by the United States.

Half of that 1071 are in Low-Earth Orbit, just a few hundred kilometers above the surface. Some of the most notable of these include the International Space Station, the Hubble Space Telescope, and many Earth observation satellites.

About a twentieth are in Medium-Earth Orbit, around 20,000 kilometers up, which are generally global positioning satellites used for navigation. A small handful are in elliptical orbits, where their orbit brings them closer and further to the Earth.
The rest are in geostationary orbit, at an altitude of almost 36,000 kilometers.

If we could see these satellites from Earth’s surface, they would appear to hang motionless in the sky. The fact that they remain over the geographic same area means they provide the perfect platform for telecommunications, broadcast or weather observations.

But there are many, many more artificial objects orbiting the Earth. In this collection of space debris we’re talking spent boosters, dead satellites, and even misplaced gloves. According to the United States Space Surveillance Network, there are more than 21,000 objects larger than 10 cm orbiting the Earth. Just a small fraction of these are operational satellites. It’s estimated there are a further 500,000 bits and pieces between 1 and 10 cm in size.

Near Earth orbit is so polluted with junk that the International Space Station is often moved to avoid impact with dangerous chunks of space debris. Many of these objects are created through collisions, and some scientists are worried that future space travel might be too risky if we get too much junk orbiting the planet. We might seal ourselves inside a shield of shrieking metal moving at 29,000 km/hour.

Looking outwards from our own orbit, at any time there are a handful of satellites orbiting the Moon. Right now, NASA’s Lunar Reconnaissance Orbiter and Lunar Atmosphere and Dust Environment Explorer are in lunar orbit. Further still, there’s 1 spacecraft around Mercury, 1 at Venus, 3 visiting Mars and 1 orbiting Saturn. There’s a handful of spacecraft orbiting the Sun, although they’re leading or trailing the Earth in its orbit. And a few spacecraft are on trajectories to take them out of the Solar System entirely. NASA’s Voyager spacecraft, exited the Sun’s heliosphere in 2013, and entered the interstellar medium.

Starting with Sputnik’s lonely journey over 50 years ago, It’s amazing to consider just how many satellites we’ve already launched into space in just a few decades. With more launches all the time, space is becoming a busy place, with so many exciting missions to look forward to.

We have written many articles about satellites for Universe Today. Here’s an article about two satellites that collided in Earth orbit, and here are some pictures of satellites.

You can learn more about the US Space Surveillance Network from the United States Strategic Command website.

We have also recorded a whole episode of Astronomy Cast about space junk. Listen here, Episode 82: Space Junk.

Astronomy Cast 318: Escape Velocity

Sometimes you’ve just got to get away from it all. From your planet, your Solar System and your galaxy. If you’re looking to escape, you’ll need to know just what velocity it’ll take to break the surly bonds of gravity and punch the sky.

Visit the Astronomy Cast Page to subscribe to the audio podcast!

We record Astronomy Cast as a live Google+ Hangout on Air every Monday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.

Virtual Star Party – October 20, 2013: In Space, Nobody can Hear You Waka-Waka-Waka-Waka!

Sunday’s Virtual Star Party felt like a reunion, with Mike Phillips, Gary Gonella, and Roy Salisbury supplying images and Scott Lewis co-hosting. We were joined by newcomer James McGee streaming a beautiful view of the Moon – when it wasn’t blocked by his apartment tower.

The Moon was just past full, so it commanded attention, but we still got a beautiful view of some fainter nebulae, galaxies and star clusters.

Astronomers: Mike Phillips, Gary Gonella, Roy Salisbury, James McGee

Hosts: Fraser Cain, Scott Lewis

Objects: The Moon, Pac Man Nebula, Eagle Nebula, Swan Nebula, Lagoon Nebula, Andromeda Galaxy, M15 globular cluster, Dumbbell Nebula, Veil Nebula and more.

We hold the Virtual Star Party every Sunday night when it gets dark on the West Coast of North America. You can watch it live on Universe Today, on Google+, or from the Universe Today YouTube Channel.

Why is Mars Red?

Why is Mars Red?

Another name for Mars is the Red Planet, and if you’ve ever seen it in the sky when the planet is bright and close to Earth, it appears like a bright red star. In Roman mythology, Mars was the god of war, so… think blood.

Even photos from spacecraft show that it’s a rusty red color. The hue comes from the fact that the surface is *actually* rusty, as in, it’s rich in iron oxide.

Iron left out in the rain and will get covered with rust as the oxygen in the air and water reacts with the iron in the metal to create a film of iron oxide.

Mars’ iron oxide would have formed a long time ago, when the planet had more liquid water. This rusty material was transported around the planet in dust clouds, covering everything in a layer of rust. In fact, there are dust storms on Mars today that can rise up and consume the entire planet, obscuring the entire surface from our view. That dust really gets around.

But if you look closely at the surface of Mars, you’ll see that it can actually be many different colours. Some regions appear bright orange, while others look more brown or even black. But if you average everything out, you get Mars’ familiar red colour.

If you dig down, like NASA’s Phoenix Lander did in 2008, you get below this oxidized layer to the rock and dirt beneath. You can see how the tracks from the Curiosity Rover get at this fresh material, just a few centimeters below the surface. It’s brown, not red.

And if you could stand on the surface of Mars and look around, what colour would the sky be? Fortunately, NASA’s Curiosity Rover is equipped with a full colour camera, and so we can see roughly what the human eye would see.

The sky on Mars is red too.

The sky here is blue because of Raleigh scattering, where blue photons of light are scattered around by the atmosphere, so they appear to come from all directions. But on Mars, the opposite thing happens. The dust in the atmosphere scatters the red photons, makes the sky appear red. We have something similar when there’s pollution or smoke in the air.

But here’s the strange part. On Mars, the sunsets appear blue. The dust absorbs and deflects the red light, so you see more of the blue photons streaming from the Sun. A sunset on Mars would be an amazing event to see with your own eyes. Let’s hope someone gets the chance to see it in the future.
We have written many articles about Mars on Universe Today. Here’s an article about a one-way, one-person trip to Mars, and here’s another about how scientists know the true color of planets like Mars.

Here are some nice color images captured of the surface of Mars from NASA’s Pathfinder mission, and here’s another explainer about why Mars is red from Slate Magazine.

We have recorded several podcasts just about Mars. Including Episode 52: Mars and Episode 92: Missions to Mars, Part 1.

Sources:
http://quest.arc.nasa.gov/qna/questions/FAQ_GeneraL_Mars.htm
http://mpfwww.jpl.nasa.gov/programmissions/missions/past/pathfinder/
http://www.slate.com/id/2093779/

Weekly Space Hangout – October 18, 2013: Penny4NASA, SpaceX Plans, ISON Lives!

This week for the Weekly Space Hangout, we were joined by an impressive team of space journalists and special guest John Zeller, the Founder of Space Advocates – they’re best known for their Penny4NASA campaign.

We discussed the government shutdown, cool reusable spacecraft and electric aircraft, exoplanets, non-killer asteroids, tilted planets and much much more.

Host: Fraser Cain

Special Guest: John Zeller, Founder of Space Advocates

Journalists: Alan Boyle, Brian Wang, David Dickinson, Elizabeth Howell

Government Shutdown Ends
SpaceX Reusable Spacecraft
Kepler Tilted Planets
1000 Exoplanets
Microairports with Electric VTOL Aircraft
Asteroid 2013 TV135
Upcoming Lunar Eclipse
Upcoming Solar Eclipse

We organize the Weekly Space Hangout every Friday afternoon at 12:00 pm Pacific / 3:00 pm Eastern. You can watch it on Universe Today, Google+ or the Universe Today YouTube channel.

How Will the Universe End?

How Will the Universe End?

The evidence that the Universe began with the Big Bang is very compelling. 13.8 billion years ago, the entire Universe was compressed into a microscopic singularity that grew exponentially into the vast cosmos we see today. But what does the future hold? How will the Universe end?

Astronomers have been pondering the ultimate fate of the Universe for thousands of years. In the last century, cosmologists considered three outcomes for the end of everything, and it all depended on the critical density of the Universe. If this critical density was high, then there was enough mutual gravity to slow and eventually halt the expansion. Billions of years in the future, it would then collapse in on itself again, perhaps creating another Big Bang. This is known as a closed Universe, and the final result is the Big Crunch.

If the critical density was low, then there wouldn’t be enough gravity to hold things together. Expansion would continue on forever and ever. Stars would die, galaxies would be spread apart, and everything would cool down to the background temperature of the Universe. This is an open Universe, and the end is known as the Big Freeze.

And if the critical density was just right, the Universe’s expansion goes on forever, but it’s always slowing down, reaching a dead stop in an infinite amount of time. This creates a Flat Universe… also a Big Freeze.

Fortunately, astronomers were able to measure the critical density of the Universe, using NASA’s WMAP spacecraft, and they discovered that the actual density of the Universe predicts a flat Universe. So that’s it, right? Of the three choices, the answer is #3.

Unfortunately, nature had other plans, and came up with a reality that nobody expected. In 1998, a team of astronomers were observing distant supernovae to get a sense of how fast the Universe is slowing down and they made an amazing discovery. Instead of decelerating, as predicted by the critical density of the Universe, the expansion of the Universe is actually speeding up.

Some mysterious force is pushing galaxies faster and faster away from each other, accelerating the expansion of the Universe. We now call this force “dark energy”, and for the time being, astronomers have no idea what it is. All we know is that it’s pushing the Universe apart. Distant galaxies are being accelerated away from us, and in trillions of years from now, they will cross the beyond the cosmic horizon and disappear from view. The evidence that we live in a vast Universe will disappear with them.

Galaxies from the Hubble Ultra Deep Field Image
Galaxies spinning farther and farther away from each other

But there’s a further unsettling possibility about dark energy. Maybe the expansion pressure will increase, eventually overwhelming gravity on a local level. Galaxies will get torn apart, and then Solar Systems, and eventually atoms themselves will be shredded by the increasing dark energy – this idea is known as the Big Rip.

So how will the Universe end? The force of dark energy will continue to accelerate the expansion of the Universe until distant galaxies disappear. Galaxies will use up all the gas and dust for stars and go dark, perhaps becoming black holes. Those black holes will decay and maybe matter itself will decay into pure energy. The entire Universe will become a cold, quiet place, where single photons are stretched across light years of space.

Don’t worry, though, that won’t be for quadrillions of years from now.