Posted on by Fraser Cain

How Long Does it Take to Get to Venus?

Artist's conception of Venus Express. Image credit: ESA

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Although humans have never made the voyage, spacecraft from Earth have visited Venus. So, how long does it take to get to Venus from Earth?

The first spacecraft ever launched towards Venus was the Soviet Venera 1 spacecraft. It was launched on February 12, 1961 on course to Venus. Unfortunately, scientists lost contact with the spacecraft on February 17th. Mission controllers didn’t get a chance to put in a course correction that would have directed it closer to Venus, so it’s thought to have passed within 100,000 km of the planet on May 19th. That’s a total time of 97 days; just over 3 months.

The first successful Venus flyby was NASA’s Mariner 2. This spacecraft was launched on August 8th, 1962 and made a successful flyby on December 14, 1962. So that calculates to 110 days from launch to arrival at Venus.

The most recent spacecraft to fly to Venus was ESA’s Venus Express. It was launched on November 9th, 2005, and took 153 days to make the journey to Venus.

Why is there such a big difference in travel times to Venus? It all comes down to the launch speed and trajectory. Both Earth and Venus are traveling on orbits around the Sun. You don’t just point your spacecraft directly at Venus and fire your rockets. You have to travel on a transfer orbit that moves you between Earth’s orbit and Venus’ orbit, catching up with Venus, ideally going into orbit. To make the trip with a smaller, less expensive rocket, you have to make a longer trip, taking more time.

Humans have never made the trip to Venus, but maybe someday they will; although, the planet would be extremely unpleasant to try and land on. Maybe just a flyby would be nice.

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 NASA’s Solar System Exploration Guide to Venus.

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

Posted on by Nancy Atkinson

Keep Track of NEOs with New “Asteroid Watch” Website

With the recent impact on Jupiter, a lot of people out there have asteroids on their mind and wonder if one could possibly hit Earth. Now, NASA and JPL have a new website called “Asteroid Watch” which will keep everyone updated if any object approaches Earth. They’ve also created an Asteroid Watch Twitter account that Tweet updates on NEOs, plus there’s a downloadable widget as well.

“The goal of our Web site is to provide the public with the most up-to-date and accurate information on these intriguing objects,” said Don Yeomans, manager of NASA’s Near-Earth Object Program Office at JPL.

“This innovative new Web application gives the public an unprecedented look at what’s going on in near-Earth space,” said Lindley Johnson, program executive for the Near-Earth Objects Observation program at NASA Headquarters in Washington.

Information is garnered from surveys and missions that detect and track asteroids and comets passing close to Earth. The Near-Earth Object Observation Program, commonly called “Spaceguard,” also plots the orbits of these objects to determine if any could be potentially hazardous to our planet.

There’s also another non-NASA Twitter feed called lowflyingrocks that lets you know about every Near Earth Object that passes within 0.2AU of Earth.

Source: JPL

Posted on by Tammy Plotner

Observe the Jupiter Impact Site!

July 28, 2009 Jupiter Impact Site by John Chumack

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Have you stayed up late and observed the Jupiter impact site? Then don’t be goofing around. Not since July 16-22, 1994 when comet Shoemaker-Levy crashed into Jupiter’s southern hemisphere have amateur astronomers had the opportunity to witness history firsthand! What makes me think that you can do it? Because I have…

Not only have cameras been clicking around the world, but they’ve been rolling, too.. Let’s take a look at one from John Chumack!

These images were done from his backyard Observatory in Dayton, Ohio USA, using A DMK 21F04 Fire-wire Camera and 2x Barlow, Optec Filter Wheel, attached to a Meade 10″ SCT scope. Captured images starting about 2:00 am and ran until 4:30 am E.ST. on 07-28-09. Basically 2.5 hours of rotation compressed to about 10 seconds. Way to go, John!!

If you think you have to be a professional, then think again. Even with less than perfect sky conditions, the impact site is very noticeable in a telescope as small as 4.5″ on a swimmy horizon and just gets better and easier to see as it reaches meridian and Jupiter reaches better sky position. DO NOT wait on the perfect night and the perfect time – because it just might not happen.

Another reason for my observations was to see just how close my predictions were… and without using a computer program? Hey… The old girl still has got it. Get thee out there on these Universal dates and times! July 29, 4:14, 14:20 and 23:59; July 30, 10:01 and 19:56; July 31, 5:52 and 15:48. For August 1, 01:43, 11:39, 21:34; August 2, 7:32 and 17:25; August 3, 3:23, 13:17 and 23:12; August 4, 9:08 and 19:03; August 5, 4:59 and 14:54; August 6, 0:50, 10:46 and 20:41; August 7, 6:37 and 16:32; August 8, 2:28, 12:24 and 22:18; August 9, 8:15 and 18:20; August 10, 4:06, 14:01, 23:57; August 11, 9:53 and 19:48; August 12, 5:42 and 15:39; August 13, 01:35, 11:31 and 21:26; August 14, 7:22 and 17:17; August 15, 3:13, 13:08, 23:04. I might be off by a few minutes, but I’m not that far off.

Take your time and do not just glance at Jupiter and think it’s not there at the predicted time – because it is. The charcoal gray oval is big enough and dark enough to stand out against the wash of the southern hemisphere, but sometimes you have to wait on a moment of clarity to see it. Try using a variety of color filters, but instead of installing them in the eyepiece, use the “blink” method. Hold the filter by the cell and simply set it on the eyepiece while you look through it, then take it off and look again. Once you see the mushroom cloud, you can’t “un-see” it.

History is waiting on you… Carpe noctem, baby!

Many, many thanks to John Chumack of Galactic Images for sharing this wonderful capture of what I was looking at last night and allowing me to adjust his original image to highlight the impact region!

Posted on by Fraser Cain

Weight on Venus

Earth and Venus. Image credit: NASA

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Want to lose some weight? Travel to Venus and you’ll feel lighter right away. Well, the high temperatures, intense pressures, and corrosive chemicals will make the experience unpleasant (and kill you instantly), but you’ll definitely be lighter on the scales. So what would your weight be on Venus?

The force of gravity on the surface of Venus is 90% the force of gravity you experience on Earth. In other words, if your bathroom scale reads 100 kg, it would only read 90 kg on Venus. For you imperial folks, if you weighed 150 pounds on Earth, you would weigh 135 pounds on Venus.

If Earth and Venus are considered twin planets, why wouldn’t you weigh the same? Well, Venus and Earth are very similar, but they’re not actually twin planets. Venus is only 95% the size of Earth, and 81% of its mass. With the smaller size and mass, the force of gravity pulling you on the surface is lower.

To get your weight on Venus, just multiply your current weight by 0.9. That’s why 100 pounds becomes 90 pounds. You can also do the reverse calculation and figure out how high you could jump, or what you could carry on Venus by dividing a number by 0.9. For example, the world record high jump is currently 2.45 meters. If that was done on Venus, it would be 2.72 meters (2.45 / 0.9).

Just one last thing. It’s important to note that kilograms are a measure of mass; how much stuff an object has. Your mass doesn’t change when you travel from planet to planet, or anywhere in the Universe. It would be more accurate to measure your weight in newtons, but bathroom scales don’t have that option. That’s why we say that your weight in kilograms changes from planet to 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 NASA’s Solar System Exploration Guide to Venus.

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

Posted on by Nancy Atkinson

Where In The Universe #64



It’s time once again for another Where In The Universe Challenge. Test your visual knowledge of the cosmos by naming where in the Universe this image was taken and give yourself extra points if you can name the spacecraft responsible for this picture. Post your guesses in the comments section, and check back later at this same post to find the answer. To make this challenge fun for everyone, please don’t include links or extensive explanations with your answer. Good luck!

UPDATE: The answer has now been posted below.

This is a false color picture of Callisto, taken by Voyager 2 on July 7, 1979 from about 1,094,666 kilometers (677,000 miles) away. The surface of Callisto is the most heavily battered and cratered of the Jupiter’s moons and resembles ancient heavily cratered terrains on the Moon, Mercury and Mars. The bright areas are ejecta thrown out by relatively young impact craters. A large ringed structure, probably an impact basin, is shown in the upper left part of the picture.

How’d you do?

Check back next week for another WITU Challenge!

Posted on by Anne Minard

Closest-Ever Look At Betelgeuse Reveals its Fiery Secret

Artist’s impression of the supergiant star Betelgeuse as it was revealed with ESO’s Very Large Telescope. Credit: ESO/L.Calçada

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The giant star Betelgeuse churns out gas bubbles that match its own size — and that’s how it can shed an entire solar mass in 10,000 years.

That according to the sharpest-ever images of Orion’s second-brightest star, released this week by the European Organisation for Astronomical Research in the Southern Hemisphere (ESO). At left is an artist’s impression of the supergiant star Betelgeuse as it was revealed in the new images (courtesy of ESO and L.Calçada). The actual images follow …

This collage shows the Orion constellation in the sky (Betelgeuse is identified by the marker), a zoom towards Betelgeuse, and the sharpest ever image of this supergiant star, which was obtained with NACO on ESO’s Very Large Telescope. Credit: ESO, P.Kervella, Digitized Sky Survey 2 and A. Fujii
This collage shows the Orion constellation in the sky (Betelgeuse is identified by the marker), a zoom towards Betelgeuse, and the sharpest ever image of this supergiant star, which was obtained with NACO on ESO’s Very Large Telescope. Credit: ESO, P.Kervella, Digitized Sky Survey 2 and A. Fujii

Betelgeuse, the second brightest star in the constellation of Orion (the Hunter), is a red supergiant, one of the biggest stars known, and almost 1,000 times larger than our Sun. It is also one of the most luminous stars known, emitting more light than 100,000 Suns.

Red supergiants still hold several unsolved mysteries. One of them is just how these behemoths shed such tremendous quantities of material — about the mass of the Sun — in only 10,000 years.

With an age of only a few million years, the Betelgeuse star is already nearing the end of its life and is soon doomed to explode as a supernova. When it does, the supernova should be seen easily from Earth, even in broad daylight.

Using ESO’s Very Large Telescope, two independent teams of astronomers have obtained the sharpest ever views of the supergiant star.

The first team used the adaptive optics instrument, NACO, combined with a so-called “lucky imaging” technique, to obtain the sharpest ever image of Betelgeuse, even with Earth’s turbulent, image-distorting atmosphere in the way. With lucky imaging, only the very sharpest exposures are chosen and then combined to form an image much sharper than a single, longer exposure would be.

The resulting NACO images almost reach the theoretical limit of sharpness attainable for an 8-metre telescope. The resolution is as fine as 37 milliarcseconds, which is roughly the size of a tennis ball on the International Space Station (ISS), as seen from the ground.

“Thanks to these outstanding images, we have detected a large plume of gas extending into space from the surface of Betelgeuse,” said Pierre Kervella from the Paris Observatory, who led the team. The plume extends to at least six times the diameter of the star, corresponding to the distance between the Sun and Neptune. “This is a clear indication that the whole outer shell of the star is not shedding matter evenly in all directions.”

Two mechanisms could explain this asymmetry. One assumes that the mass loss occurs above the polar caps of the giant star, possibly because of its rotation. The other possibility is that such a plume is generated above large-scale gas motions inside the star, known as convection — similar to the circulation of water heated in a pot.

To arrive at a solution, Keiichi Ohnaka from the Max Planck Institute for Radio Astronomy in Bonn, Germany, and his colleagues used ESO’s Very Large Telescope Interferometer. The astronomers were able to detect details four times finer still than the NACO images had allowed — in other words, the size of a marble on the ISS, as seen from the ground.

“Our AMBER observations are the sharpest observations of any kind ever made of Betelgeuse. Moreover, we detected how the gas is moving in different areas of Betelgeuse’s surface — the first time this has been done for a star other than the Sun,” Ohnaka said.

The AMBER observations revealed that the gas in Betelgeuse’s atmosphere is moving vigorously up and down, and that these bubbles are as large as the supergiant star itself. The astronomers are proposing that these large-scale gas motions roiling under Betelgeuse’s red surface are behind the ejection of the massive plume into space.

Source: European Organisation for Astronomical Research in the Southern Hemisphere (ESO). Two related papers are here and here.

Posted on by Fraser Cain

Inside of Venus

From our perspective here on Earth, Venus is completely covered in clouds. So what’s inside Venus? For most of history, scientists had no idea what’s inside of Venus. The earliest telescopes showed hazy cloud tops, and even the largest telescopes didn’t improve the view. Some astronomers thought they might have caught a glimpse of the surface through the clouds, or maybe the peak of a tall mountain poking up through the clouds. But we now know those were just observation errors.

It wasn’t until the first spacecraft from Earth arrived at Venus, and started gathering scientific data about the inside of Venus. NASA’s Mariner 2 helped scientists calculate that the density of Venus is very similar to the density of Earth. Although there were no direct observations of Venus’ interior, scientists assume that it must be similar to Earth. The inside of Venus is thought to contain a solid/liquid core of metal 3,000 km across. This is surrounded by a mantle of rock 3,000 km thick. And then there’s a thin crust of rock about 50 km thick.

When NASA’s Magellan spacecraft was launched to Venus in 1989, it was carrying a suite of powerful radar mapping instruments. These tools could pierce through the thick clouds surrounding Venus and reveal the surface of the planet in great detail. Magellan found that the surface of Venus is actually quite young, and was probably resurfaced 300-500 million years ago, based on the number of impact craters found on its surface.

Magellan also found evidence of a large number of volcanoes; they number in the thousands and maybe even in the millions. The shield volcanoes found across the surface of Venus indicate that the inside of Venus is still active, with magma pushing to the surface around the planet.

It’s believed that the event that resurfaced Venus 300-500 million years ago might have also shut down plate tectonics on Venus. Without the movement of plates to release trapped heat, the inside of Venus remained much hotter than it would be. It’s thought that this increase in heat also shut down the convection of metal around the core of Venus. It’s this convection in the Earth’s core that’s thought to run our planet’s magnetic field.

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 NASA’s Solar System Exploration Guide to 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 Solar System Exploration: Terrestrial Planets
Venus Interior

Posted on by Fraser Cain

Core of Venus

Venus is a tricky place to study because it’s shrouded in a thick atmosphere that hides its surface. And if you can’t even see its surface, imagine how difficult it must be to study the interior of Venus. But scientists have been making steady progress towards understanding the interior of the planet, and learn about the core of Venus.

Here on Earth, scientists study the core of the planet by measuring how seismic waves move through the planet after earthquakes. As they pass through the different layers of the Earth’s interior; the core, the mantle, and the crust, the waves reflect or bend depending on the change of density that they’re passing through. Well, the surface of Venus is hot enough to melt lead, and spacecraft are destroyed within a few hours of reaching the surface of Venus, so no readings have been gathered about Venus’ core directly.

Instead, scientists assume that the core of Venus exists based on calculations of its density. The density of Venus is only a little less than the density of Earth. This means that Venus probably has a core of metal about 3,000 km across, surrounded by a 3,000 km thick mantle and a 50 km thick crust.

Scientists aren’t sure if the core of Venus is solid or liquid, but they have a few hints. That’s because Venus doesn’t have a planet wide magnetic field like the Earth. It’s believed that the Earth’s magnetic field is generated by the convection of liquid in the Earth’s core. Since Venus doesn’t have a planetary magnetic field, it’s possible that Venus’ core is made of solid metal, or maybe there isn’t enough of a temperature gradient between the inner and outer core to made this convection happen.

It’s believed that a global resurfacing event that occurred about 300-500 million years ago might have something to do with this. The entire surface of Venus was resurfaced, shutting down plate tectonics. This might have led to a reduced heat flux through the crust, trapping the heat inside the planet. Without the big heat difference, there’s little heat convection, and so no magnetic field coming from the core of Venus.

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 NASA’s Solar System Exploration Guide to 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 Solar System Exploration: Terrestrial Planets
Venus Interior

Posted on by Fraser Cain

Geology of Venus

Artist's impression of the surface of Venus, showing its lightning storms and a volcano in the distance. Credit and ©: European Space Agency/J. Whatmore

Take a look at Venus in even the most powerful telescope, and all you’ll see is clouds. There are no surface features visible at all. It wasn’t until the last few decades, when radar equipped spacecraft arrived at Venus, that scientists finally had a chance to study the geology of Venus in great detail.

Spacecraft like NASA’s Magellan mission are equipped with radar instruments that let it penetrate down through the clouds on Venus and reveal the surface below. Magellan found that the surface of Venus does have many impact craters and evidence of past volcanism. But the total number of craters showed that the surface of Venus is actually pretty young. It’s likely that some catastrophic event resurfaced Venus about 300-500 million years ago, wiping out old craters and volcanoes.

Unlike Earth, Venus doesn’t have plate tectonics. It’s possible that the planet had them in the ancient past, but rising temperatures shut them down and helped the planet go into a runaway greenhouse cycle. Carbon on Earth is trapped by plants, and is then recycled into the Earth through plate tectonics. But on Venus, the tectonic system shut down, so carbon was able to build up to tremendous levels. This cycle thickened the atmosphere, raised temperatures with its greenhouse effect, releasing more carbon, raising temperatures even higher… etc.

There are volcanoes on Venus; scientists have identified more than 100 isolated shield volcanoes. And there are thousands and maybe even millions of smaller volcanoes less than 20 km across. Many of these have a strange dome-shaped structure, believed to have formed when plumes of magma thrust the crust upward and then collapsed.

Scientists can’t be exactly sure what the internal structure of Venus is like, but based on its density, Venus is probably similar to Earth in composition. It’s believed to have a solid or liquid core of metal 3,000 km across. This is surrounded by a mantle of rock 3,000 km thick, and then a thin crust of solid rock about 50 km thick.

One big difference between Earth and Venus is the lack of a planetary magnetic field at Venus. It’s believed that the Earth’s magnetic field is driven by the convection of liquid metal at the Earth’s core. If true, it means that Venus probably doesn’t have the same kind of temperature differences at its core, and lacks the convection to sustain a planetary magnetic field.

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 NASA’s Solar System Exploration Guide to Venus.

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

Reference:
NASA Solar System Exploration: Geologic Landforms of Venus
NASA Science: Blazing Venus
NASA Solar System Exploration: Venus

Posted on by Fraser Cain

Composition of Venus

Venus is often referred to as Earth’s twin planet (evil twin planet is more like it, when you consider the scorching temperatures). It’s almost the same size, mass, gravity and overall composition. The composition of Venus is pretty similar to Earth, with a core of metal, a mantle of liquid rock, and an outer crust of solid rock.

Unfortunately, scientists have no direct knowledge about Venus composition. Here on Earth, scientists use seismometers to study how seismic waves from earthquakes propagate through the planet. How these waves bounce and turn inside the Earth tell scientists about its composition. Since the surface of Venus is hot enough to melt lead, and no spacecraft have survived on the surface for longer than a few hours, there just isn’t the information about Venus’ internal composition.

Scientists can calculate the density of Venus, though. Since it’s similar to Earth, and the other terrestrial planets, scientists guess that the internal structure of Venus is similar to Earth. One of the big differences between our two planets, however, is the lack of plate tectonics on Venus. For some reason, plate tectonics on Venus shut down billions of years ago. This has prevented the interior of Venus from losing as much heat as the Earth does, and could be the reason Venus doesn’t have an internally generated magnetic field.

Before spacecraft missions were sent to Venus, scientists had no idea what the composition of Venus was. They could calculate the planet’s density, but the surface of Venus was obscured by dense clouds. Spacecraft equipped with radar were able to penetrate the thick clouds and map out features on the planet’s surface, showing that it has impact craters and ancient volcanoes. It’s believed that Venus went through some kind of global resurfacing event about 300-500 million years ago, which is the age of the planet’s surface (calculated by the number of impact craters).

The crust of Venus is thought to be about 50 km thick, and composed of silicious rocks. Beneath that is the mantle, which is thought to be about 3,000 km thick. The composition of the mantle is unknown. And then at the center of Venus is a solid or liquid core of iron or nickel. Since Venus doesn’t have a global magnetic field, scientists think that the planet doesn’t have convection in its core. The planet doesn’t have a large difference in temperature between the inner and outer core, and so the metal doesn’t flow around and generate a magnetic field.

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 NASA’s Solar System Exploration Guide to Venus.

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

References:
Geophysical Models of Western Aphrodite-Niobe
NASA Solar System Exploration: Terrestrial Planet Interiors