Universe Today

August 23, 2009December 24, 2015 by Fraser Cain

Black Hole Pictures

Magnetic field around a black hole. Image credit: NASA

Want to see some black hole pictures? Here’s a challenge, how to show an image of something that absorbs all the light that reaches it. Of course, it’s impossible to show any real pictures of black holes because they’re invisible. But you can show the regions around black holes as well as illustrations of what black holes might look like.

[/caption]

This black hole picture shows the invisible black hole at the center surrounded by an accretion disk of material. The rapid rotation of the black hole interacts with the accretion disk generating powerful magnetic fields.

Artist's illustration of a supermassive black hole. Image credit: NASA

This is a picture of a supermassive black hole (artist illustration). You’re seeing the black hole from the side, and it’s surrounded by a thick torus of gas and dust that obscures the region around the black hole from view. The powerful magnetic fields of the black hole generate powerful jets that stream out into space.

Supermassive black hole suppressing star formation. Image credit: NASA

This artist photo of a black hole shows a supermassive black hole at the center of a galaxy. Powerful radiation is streaming out of the black hole’s core, stopping star formation in regions close to the center of the galaxy.

Evidence for a spinning black hole. Image credit: NASA

This black hole picture shows a black hole spinning rapidly at the center of its accretion disk. Although the black hole itself is invisible, it’s surrounded by a fast disk of material falling into the black hole, like water going down a drain.

Here’s a black hole picture that shows a black hole in a binary relationship with a star. Material is streaming off of the star, and into an accretion disk around the black hole. The rapidly rotating black hole generates a powerful magnetic field that creates twin jets of material streaming above and below the black hole.

August 23, 2009December 24, 2015 by Fraser Cain

Who Discovered Venus?

Venus is easy to see with the unaided eye. In fact, it’s the brightest object in the night sky after the Moon, so it’s safe to say that humans have been aware of Venus since people have looked to the skies. In fact, there are 5 planets visible with the unaided eye: Mercury, Venus, Mars, Jupiter and Saturn. It’s actually impossible to say who discovered Venus, since the planet has been known since before recorded history. Humans have been on Earth for 200,000 years, so maybe that’s how long we’ve known about the planet.

But ancient astronomers didn’t really know what Venus was. They knew it was an object that moved in the sky from night to night, sometimes being obscured by the glare of the Sun. But it wasn’t until Copernicus developed his model of the Solar System that placed the Sun at the center, and the planets orbiting it. At that point, both Venus and Earth were recognized to be planets.

Galileo pointed his telescope at Venus in 1610, and confirmed Copernicus’ theory by showing that Venus went through distinct phases, just like the Moon. The phases matched the predictions made by Copernicus, and demonstrated that Venus was really a planet, orbiting the Sun and not the Earth.

This model was confirmed even more when Venus made a transit across the surface of the Sun on December 4, 1639. The most recent transit of Venus happened in 2004, and the next one will occur in 2012.

Even in the best telescopes we have today, the surface of Venus is obscured by thick clouds, so it’s impossible to see any features on its surface. It wasn’t until radar signals were bounced off Venus in 1961 that scientists had any way to calculate the planet’s speed of rotation and axial tilt.

The first spacecraft to visit Venus was Mariner 2, but more recent spacecraft, like NASA’s Magellan were equipped with radar instruments that can peer through the thick atmosphere of Venus and reveal the hellish surface below.

Spacecraft have even landed on the surface of Venus. The Russian Venera program put a handful of landers on the surface of Venus, which were able to send home images of the surface before they malfunctioned in the incredible heat and pressure found on the surface of the planet.

We have written many articles about Venus for Universe Today. Here’s an article about Venus’ wet, volcanic past, and here’s an article about how Venus might have had continents and oceans in the ancient past.

Want more information on Venus? Here’s a link to Hubblesite’s News Releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide on Venus.

We have recorded a whole episode of Astronomy Cast that’s only about planet Venus. Listen to it here, Episode 50: Venus.

References:
NASA: Transit of Venus
NASA Solar System Exploration: Venus

August 22, 2009May 4, 2017 by Fraser Cain

How Many Rings Does Saturn Have?

Saturn's Rings. Image credit: NASA/JPL/SSI

Saturn is best known for its elaborate ring system. They’re made of icy particles orbiting the planet. The rings have distinct divisions, and astronomers have separate designations for each of Saturn’s rings. But how many rings does Saturn have?

The question is actually impossible to answer. Saturn has more than a dozen rings and gaps within the rings – and more are being discovered by spacecraft like NASA’s Cassini. But the planet does have several major ring systems and gaps within them.

The two densest parts of the rings are the A and B rings, separated by the Cassini Division, and then the C Ring. So, is that 3 rings, or 4? Whatever the case, these comprise Saturn’s main rings.

After the 3 main rings, you have the smaller, dusty rings: the D Ring, G Ring, E Ring, and others beyond that. There’s also the F Ring, which is just outside the A Ring.

That’s 3 main rings and 5 dusty rings for a total of 8 rings, 9 if you count the Cassini Division.

But there are even more rings around Saturn. There’s the Janus Ring, the Methone Ring Arc, the Anthe Ring Arc and the Pallene Ring, as well as the Roche Division. 4 more rings and another division.

That brings us to 12 rings and 2 divisions.

But then there are also smaller divisions and gaps within the various rings that would bring the total to more than 30 (the Encke Gap, the Huygens Gap, the Dawes Gap, and many more).

To answer the question, how many rings does Saturn have, you really need to find out how closely you’re looking. From what you might be able to see, there are 3 rings. With powerful telescopes, you can make out 8 rings. And with spacecraft like Cassini orbiting Saturn, that total rises above 30.

We have written many articles about Saturn’s rings for Universe Today. Here’s an article about a time when Saturn’s rings were disappearing, and here’s an article about vertical structures that tower above Saturn’s rings.

Here’s the same question answered by Ask an Astronomer. Here’s an easier question, how many moons does Saturn have?

We have done an entire episode of Astronomy Cast all about Saturn. Give it a listen.

Reference:
NASA

August 22, 2009December 24, 2015 by Fraser Cain

What is the Ozone Layer?

[/caption]
The ozone layer is a region in the Earth’s atmosphere that contains high concentrations of ozone. Ozone is three molecules of oxygen bonded together, and so it has the chemical symbol O₃. The ozone layer contains more than 91% of the ozone in the Earth’s atmosphere. Because it absorbs ultraviolet radiation from the Sun, the ozone layer is vital to the evolution and survival of life on Earth.

Ozone in the Earth’s atmosphere is created when sunlight strikes oxygen molecules which consist of two oxygen atoms bonded together (O₂). This splits it into two separate oxygen atoms which float in the atmosphere until they bond with other oxygen molecules creating ozone (O₃). Ozone is unstable, though, and further ultraviolet radiation continues to break up the ozone into oxygen molecules and single oxygen atoms. This combination and breakdown is going all the time in the ozone layer.

The ozone layer is special to life because it absorbs ultraviolet radiation from the Sun in a very specific wavelength – UV-B radiation, between 315-280 nanometers in wavelength. It’s this UV-B radiation which gives us sunburns and can even cause cancer with long term radiation. Without the ozone layer, we would receive much more harmful radiation from the Sun.

Of course, one of the big worries in the last few years is the problem of ozone depletion. Certain manmade chemicals, like nitric oxide and chlorofluorocarbons break down ozone molecules, stopping them from being able to absorb ultraviolet radiation. A single molecule of one of these free radicals can break down more than 100,000 ozone molecules.

Satellites observing the Earth’s atmosphere discovered that the ongoing use of these chemicals were causing the ozone layer to thin out. Ozone layers declined at a rate of 4% per decade, mostly over the Earth’s northern and southern poles. Many countries enacted bans of ozone-destroying chemicals in 1978, and in the last few years scientists have determined that the rate of ozone depletion is slowing down.

We have written many articles about the ozone layer for Universe Today. Here’s an article about the ozone success story, and here’s an article about how the ozone layer really looks like it’s recovering.

Here’s more information on the ozone layer from NASA’s Ozone Resource Page. And here’s the ozone hole watch site.

In episode 36 of Astronomy Cast we discussed how an gamma ray burst could strip away the ozone layer of the Earth in just a moment.

August 22, 2009December 24, 2015 by Fraser Cain

How Many Rings Does Jupiter Have?

Jupiter's rings. Image Credit: University of Maryland

We’re familiar with the rings of Saturn, but did you know that Jupiter has rings too? The rings of Jupiter were first discovered by the Voyager 1 spacecraft when it passed by Jupiter in 1979. The rings were investigated in more detail by NASA’s Galileo spacecraft during the 1990s. It was during the 1990s that Galileo and ground-based observations made a complete count of the number of Jupiter’s rings. So, how many rings does Jupiter have?

Jupiter is known to have 4 sets of rings: the halo ring, the main ring, the Amalthea gossamer ring, and the Thebe gossamer ring.

The halo ring is closest into Jupiter starting at a radius of 92,000 km and extending out to a radius of 122,500 km. The halo ring has a total width of 12,500 km.

Next is the main ring. It starts at 122,500 km and extends out to 129,000 km. It has a total width of only 6,500 km.

Outside these two major rings are the gossamer rings. These are very faint rings that are shepherded by two of Jupiter’s moons. The first is the Amalthea gossamer ring, which is shepherded by Jupiter’s moon Amalthea. It starts at a radius of 129,000 km from Jupiter and goes out to the orbit of Amalthea at 182,000 km.

Overlapping the Amalthea ring is the Thebe gossamer ring. It starts at a radius of 129,000 and goes out to a radius of 226,000 km.

How many rings does Jupiter have? The answer is four. Of course, it’s always possible that new rings will be discovered around Jupiter as new and better spacecraft and telescopes examine the planet.

We have written many articles about Jupiter and its rings for Universe Today. Here’s an article about how Jupiter’s rings are made in the shade. And here are some interesting discoveries made by NASA’s New Horizon’s spacecraft when it arrived at Jupiter.

Windows to the Universe has more information about Jupiter’s rings. And here’s more information on the rings from NASA.

We have recorded a whole episode of Astronomy Cast just about Jupiter, and in that episode we talked about the planet’s rings.

Reference:
NASA

August 22, 2009December 24, 2015 by Fraser Cain

Milky Way Galaxy Pictures

Artist impression of the Milky Way. Image credit: NASA

Here are some beautiful pics of the Milky Way Galaxy. It’s important to remember that we live inside the Milky Way Galaxy, so there’s no way to show a true photograph of what the Milky Way looks like. We can see pictures of the Milky Way from inside it, or see artist illustrations of what the Milky Way might look like from outside.

[/caption]

This Milky Way Galaxy picture shows what our galaxy would look like from above. You can see its spiral arms, dense core and the thin halo. The Milky Way is a common barred spiral galaxy. There are billions more just like it in the Universe.

Milky Way in infrared. Image credit: COBE

This picture of the Milky Way was captured by NASA’s COBE satellite. This photograph was taken using the infrared spectrum, which allows astronomers to peer through the gas and dust that normally obscures the center of the Milky Way.

The plane of the Milky Way, recorded with the Chandra satellite in three colours: Photons with energies between 0.5 and 1keV appear red, those between 1 and 3keV green, and those between 3 and 7keV blue. Discrete sources are indicated by circles. Image: Mikhail Revnivtsev

This image of the Milky Way Galaxy was taken with the Chandra X-Ray Observatory, which can see in the X-Ray spectrum. In this view, only high energy emissions are visible, such as the radiation emitted from black holes and other high energy objects.

Artist's concept shows young, blue stars encircling a supermassive black hole at the core of a spiral galaxy like the Milky Way.Credit: NASA, ESA, and A. Schaller (for STScI)

Here’s an artist’s impression of what a galaxy like the Milky Way might have looked like early in its history. This image shows a supermassive black hole with young blue stars circling it.

Milky_Way_infrared_mosaic. Credit: Spitzer Space Telescope

This is a mosaic image of the Milky Way captured by NASA’s Spitzer Space Telescope. It was built up by several photographs taken by Spitzer, which sees in the infrared spectrum, and can peer through obscuring dust.

August 22, 2009December 24, 2015 by Abby Cessna

What Are Planets?

The mysterious Eris and moons. Credit: NASA

[/caption]

Throughout history, the definition of what a planet is has changed and meant various things at the same time depending on who was defining it. Objects like the Sun, which we would now scoff at defining as a planet, was once considered just that, and so was the Moon. Ceres, discovered in 1801, was originally thought to be a planet until astronomer discovered Pallas that has a similar orbit. Astronomers, even using the technology of their time, were able to tell that these objects were not planets. The famous astronomer Sir William Herschel suggested the name “asteroids” which stuck. Asteroids were then accepted as a distinct category.

Several years ago, you may have said that a planet is one of the nine large celestial bodies that orbits the Sun. However, new technology, which made the discovery of many new celestial bodies in various regions, such as the Kuiper Belt, possible also made determining what a planet is more difficult. While a number of people suggested various definitions over the years, none of them were widely accepted.

The issue came to a head in 2005 when an object larger than Pluto is was discovered beyond the Kuiper Belt. This object, which is now called Eris, was a source of division among many. Some astronomers wanted Eris to be the tenth planet while others considered it to be just another asteroid, despite the fact that it is larger than Pluto is. The International Astronomical Union (IAU), which usually resolves disputes like this, met in 2005 at a conference, but despite debating the issue, they did not come up with an agreed upon definition. The matter was resumed in summer of 2006 at the next IAU conference.

In August 2006, the IAU finally agreed upon a definition for a planet. The IAU’s official definition was, “A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.” An object that has cleared the neighborhood of its orbit is of sufficient size for its gravity to force other objects of similar size out of its orbit. In addition to defining what a planet is, the IAU also created a new category of dwarf planets, which Pluto was reclassified as, and Eris and several other objects were also put in that category. The definition has had severe opposition, especially with many people angry at the demotion of Pluto.

Universe Today has articles on dwarf planets and planet.

For more information, try an overview of the planets and what is a planet.

Astronomy Cast has episodes on all the planets including Venus.

August 22, 2009December 24, 2015 by Abby Cessna

Solar System Projects for Kids

[/caption]

Discovery Education has eight projects on the Solar System that you can do with a class or a single child. Many of them are also great projects for a science fair or a report. This website also has games to play and some ideas on how to get your students or children interested in space as well as a quiz to make sure that the material has been mastered.

Cool Science Projects has some suggestions on various projects for a science fair as well as some background material on the Solar System.

Enchanted Learning has a number of Solar System crafts that are simple enough for young children probably in kindergarten or grades 1 through 3. There are also coloring pages about the Solar System that can be printed.

The AOK Corral has a project painting a glow in the dark Solar System, which is a great twist on an old classic. You can take the idea of using the glow in the dark paint a step further and create a glow in the dark mural for a kid’s room.

How Stuff Works has some great projects for kids including one on how to make your own planetarium and learning how to create your own astrolabe.

A to Z Home’s Cool Homeschooling has a ton of links to great projects and experiments you can try. Some of these links let you figure out your weight on other planets. You can also get information on all the planets in the Solar System.

One of the best resources for your space needs is NASA. NASA has materials for children including games to play and projects for science fairs as well as information on the planets and all the other objects in the Solar System. They also have materials for children of different ages and even resources for college students. NASA even has information on how to get a guest speaker from NASA at your school.

Universe Today has articles on what the Solar System is and all the planets.

For more information check out an overview of the Solar System and the Solar System for kids.

Astronomy Cast has episodes on all the planets including Jupiter.

August 21, 2009December 24, 2015 by Nancy Atkinson

If You Don’t Have an LHC, Here’s How to Create Your Own Black Hole

[/caption]
Those fearful folks who have worried about the Large Hadron Collider creating a black hole that could swallow the Earth have probably been feeling pretty safe while the giant particle accelerator is still offline. But hopefully they haven’t read the latest Physical Review Letters . It includes a paper that explains how researchers at Dartmouth have figured out a way to create a tiny quantum-sized black hole in their lab, with no LHC required.

In their paper, the researchers show that a magnetic field-pulsed microwave transmission line containing an array of superconducting quantum interference devices, or SQUIDs, not only reproduces physics similar to that of a radiating black hole, but does so in a system where the high energy and quantum mechanical properties are well understood and can be directly controlled in the laboratory. The paper states, “Thus, in principle, this setup enables the exploration of analogue quantum gravitational effects.”

“We can also manipulate the strength of the applied magnetic field so that the SQUID array can be used to probe black hole radiation beyond what was considered by Hawking,” said Miles Blencowe, an author on the paper and a professor of physics and astronomy at Dartmouth.

Creating a black hole would allow researchers to better understand what physicist Stephen Hawking proposed more than 35 years ago: black holes are not totally void of activity; they emit photons, which is now known as Hawking radiation.

“Hawking famously showed that black holes radiate energy according to a thermal spectrum,” said co-author Paul Nation. “His calculations relied on assumptions about the physics of ultra-high energies and quantum gravity. Because we can’t yet take measurements from real black holes, we need a way to recreate this phenomenon in the lab in order to study it, to validate it.”

This is not the first proposed imitation black hole, Nation said. Other proposed schemes to create a black hole include using supersonic fluid flows, ultracold bose-einstein condensates and nonlinear fiber optic cables. However, these ideas wouldn’t work as well to study Hawking radiation because the radiation in these methods is incredibly weak or otherwise masked by commonplace radiation due to unavoidable heating of the device, making it very difficult to detect. “In addition to being able to study analogue quantum gravity effects, the new, SQUID-based proposal may be a more straightforward method to detect the Hawking radiation,” said Blencowe.

Source: Dartmouth U

August 21, 2009April 26, 2016 by Tammy Plotner

IYA Live Telescope Today: NGC 247, the Burbidge Galaxy Chain and the Running Man Nebula

Did you get a chance to watch the IYA “Live” Telescope today? We were on! And now we’ve got some exciting news for you… You can watch via your iPhone on TVU! That’s right… We’re now broadcasting on Channel 79924 as Northern and Southern Galactic TV. You can watch Galactic TV via your iPhone by installing TVUPlayer from the App Store! Now… Are you ready for today’s video? Then hang on tight as we take you a walk to NGC 247, the Burbidge Galaxy Chain and the Running Man Nebula! It’s time to rock….

Skies were clear and dark in Central Victoria and it was time to fire up the IYA Live Telescope and get the party started. We’re testing out a new system that will allow more viewers an opportunity to see through the virtual eyepiece and we’re ready to get the scope set on a something really far out. Our first object? NGC 247 and the Burbidge Galaxy Chain in the constellation of Cetus…

This interesting chain of four MCG galaxies lies only 18 arc minutes NNE of NGC 247, a giant member of the nearby Sculptor Group. (NGC 247 itself is 9th-magnitude but of very low surface brightness, which can make it tough to spot in a smaller scope.) In itself, NGC 247 is an Intermediate spiral galaxy located over 12 million light years away. Talk about a long distance phone call!

The northernmost and southernmost members of the chain are relatively easy to pick up in a 17.5″ scope. That’s aperture – not tube length! Bwahahahahaaaaa….

Last object for the night? Lace up your Nikes, cuz’ we’re heading for NGC 1977, the “Running Man Nebula” in Orion…

NGC 1973/5/7 is a reflection nebula 1/2 degree northeast of the Orion Nebula. The three NGC objects are divided by darker regions.

It was discovered on January 18, 1784 by Sir William Herschel, seasoned sky veterans know this area by its nickname ‘‘the Running Man’’. Consisting of three separate areas of emission and reflection nebulae that seem to be visually connected, 1,500-light-year-distant NGC 1977/1975/1973 complex would be spectacular on its own if weren’t so close to M42! The conjoining nebula is whispery soft, its dark lanes created by interstellar dust and fine needle-like shards of carbon. Illuminating the gases is its fueling source, the multiple star 42 Orionis—a prized double on many lists. Through a telescope, this lovely triangle of bright nebulae and its several enshrouded stars make a wonderful region for exploration. Can you see the Running Man within?

As of the time of this posting, the scope was still up and running… along with the nebula! We’re making every effort when the sky is clear to keep the view coming at you, dear reader. So keep checking back often and enjoy the new iPhone application! If things keep working the way they should, you should be able to enjoy a video loop of many of our best objects at all times… We hope!

Fingers crossed…