Posted on by Matt Williams

The Orbit of Venus. How Long is a Year on Venus?

Venus captured by Magellan.

Venus and Earth have many similarities. Both are terrestrial planets, meaning that they are composed predominately of metal and silicate rock, which is differentiated between a metal core and a silicate mantle and crust. Both also orbit the Sun within its habitable zone (aka. “Goldilocks Zone“). Hence why Venus and Earth are often called “sister planets”.

However, Venus is also starkly different from Earth in a number of ways. It’s atmosphere, which is composed primarily of carbon dioxide and small amounts of nitrogen, is 92 times as dense as Earth’s. It is also the hottest planet in the Solar System, with temperatures hot enough to melt lead! And on top of all that, a year on Venus is much different than a year on Earth.

Orbital Period:

Venus orbits the Sun at an average distance of about 0.72 AU (108,000,000 km/67,000,000 mi) with almost no eccentricity. In fact, with its farthest orbit (aphelion) of 0.728 AU (108,939,000 km) and closest orbit (perihelion) of 0.718 AU (107,477,000 km), it has the most circular orbit of any planet in the Solar System.

Earth and Venus’ orbit compared. Credit: Sky and Telescope

The planet’s orbital period is 224.65 days, which means that a year on Venus is 61.5% as long as a year on Earth. Unlike most other planets in the Solar System, which rotate on their axes in an counter-clockwise direction, Venus rotates clockwise (called “retrograde” rotation). It also rotates very slowly, taking 243 Earth days to complete a single rotation.

Sidereal vs. Solar Day:

While a year on Venus lasts the equivalent of 224.65 Earth days, it only lasts the equivalent 1.92 days on Venus. This is due to the fact that Venus rotates quick slowly and in the opposite direction of its orbit. Because of this, a Solar Day – the time it takes for the Sun to rise, set, and return to the same place in the sky – takes 116.75 Earth days.

This means, in effect, that a single day on Venus lasts over half a year. In other words, in the space of just over a single Venusian year, the Sun will appear to have circled the heavens twice. In addition, to someone standing on the planet’s surface, the Sun would appear to rise in the west and set in the east.

Variations:

Because of its dense atmosphere and its highly circular rotation, Venus experiences very little in the way of temperature variations during the course of a year. Similarly, its axial tilt of 2.64° (compared to Earth’s 23.44°) is the second-lowest in the Solar System, behind Mercury’s extremely low tilt of 0.03.

This means that there is virtually no variation in Venus’ surface temperature between day and night, or the equator and the poles. All year long, the mean surface temperature of Venus is a scorching 735 K (462 °C/863.6 °F), with the only variations occurring as a result of elevation.

Yes, Venus is a truly hellish place. And unfortunately, that’s a year-round phenomena! The days are extremely hot, the nights extremely hot, and a day lasts over half as long as a year. So if you’re planning on vacationing somewhere, might we recommend somewhere a little less sunny and balmy?

We’ve written several articles about years on other planets here at Universe Today. Here’s How Long is a Year on the Other Planets?, Which Planet has the Longest Day?, How Long is a Year on Mercury?, How Long is a Year on Earth?, How Long is a Year on Mars?, How Long is a Year on Jupiter?, How Long is a Year on Saturn?, How Long is a Year on Uranus?, How Long is a Year on Neptune?, How Long is a Year on Pluto?

If you’d like more info on Venus, check out Hubblesite’s News Releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide on Venus.

We’ve also recorded an episode of Astronomy Cast all about Venus. Listen here, Episode 50: Venus.

Sources:

Posted on by Matt Williams

United Arab Emirates Has a Plan to Colonize Mars with 600,000 People in 100 Years

Artist's concept for a possible colony on Mars, which the United Arab Emirates indicated it is committed to building by 2117. Credit: Ville Ericsson

Elon Musk has been rather outspoken in recent years about his plan to create a human settlement on Mars. Stressing the need for a “backup location” for humanity, he has dedicated his company (SpaceX) to the creation of a reusable spacecraft (aka. the Interplanetary Transport System) that in the coming decades will be able to transport one-hundred people at a time to Mars.

In addition to Musk, Dutch entrepreneur Bas Lansdorp has also expressed an interest in creating a permanent settlement on Mars. In 2012, he founded MarsOne with the intent of developing the necessary expertise to mount one-way trips to the Red Planet by 2032. And according to an announcement from the government of Dubai, it seems they aren’t the only ones looking to colonize the Red Planet.

The announcement came on February 14th, 2017, during the 5th World Government Summit – which was held this year in Dubai. In the midst of presentations by notaries like Ban-Ki-Moon, Elon Musk, and Barack Obama, Sheikh Mohammed bin Rashid Al Maktoum and Sheikh Mohamed bin Zayed Al Nahyan shared their country’s vision of putting 600,000 humans on the Red Planet by the next century – known as the “Mars 2117 Project”.

In the course of his speech, Sheikh Mohammed emphasized the UAEs commitment to space sciences and its desire to accomplish one of the longest-held dreams of humanity:

“Human ambitions have no limits, and whoever looks into the scientific breakthroughs in the current century believes that human abilities can realize the most important human dream. The new project is a seed that we plant today, and we expect future generations to reap the benefits, driven by its passion to learn to unveil a new knowledge. The landing of people on other planets has been a longtime dream for humans. Our aim is that the UAE will spearhead international efforts to make this dream a reality.”

As growing investors in the field of space research, Sheikh Mohammed indicated that this project will accelerate the UAE’s commitment in this regard. Recent accomplishments by the Emirati space program include the successful deployment of the UAE’s first nanosatellite – Nayif-1 – which was launched a day after the Mars 2117 announcement (Feb. 15th, 2017).

This nanosatellite was the result of collaborative work between the Mohammed bin Rashid Space Centre (MBRSC) and the American University of Sharjah (AUS). Its intended purpose is to provide opportunities and hands-on experience for Emirati engineering students, as well as developing expertise in the designing, building, testing and operating of nanosatellites.

And then there’s the Hope Spacecraft, a project which was commissioned in 2015 by the Emirates Mars Mission. This project calls for the creation of a compact, hexagonal spacecraft that will reach the Red planet by 2021 and spend the next two years studying its atmosphere and weather. Not only is this mission designed to provide the first truly global picture of the Martian atmosphere, it will also be the first orbiter deployed by an Arab country.

Meanwhile, Sheikh Mohamed bin Zayed – the Crown Prince of Abu Dhabi and the Deputy Supreme Commander of the UAE Armed Forces – said that the objective of the project is to develop the skills and capacities of the UAE’s space program. He also indicates that the project will benefit research institutions and advance the fields of transportation, energy and food production here on Earth.

“The Mars 2117 Project is a long term project, where our first objective is to develop our educational system so our sons will be able to lead scientific research across the various sectors,” he said. “The UAE became part of a global scientific drive to explore space, and we hope to serve humanity through this project.”

Elements of the project were showcased at the Summit by a team of Emirati engineers, scientists and researchers – which included a concept for a human city that would be built by robots. It also showcased aspects of the inhabitants’ lifestyle, like the transportation they would use, how they would generate power, how they would grow food, the infrastructure they would build, and the materials that would be used to construct the colony.

An artist's illustration of a Mars settlement. Image: Bryan Versteeg/MarsOne
An artist’s illustration of an early Mars settlement. Credit: Bryan Versteeg/MarsOne

Given the long-term nature of this project, it will be broken down into multiple phases that will take place over the next few decades. Phase One will focus on preparing the scientists who will attempt to address all the challenges and concerns of sending human beings on a one-way trip to Mars. At the same time, the project calls for the creation of an Emiratis science team that will work with the international scientific community to speed up the research efforts.

Particular areas of concern will include creating spacecraft that are fast enough to ferry people to and from Earth in a respectable time frame. Then there’s the task of creating a working model of what the settlement will look like, and how the needs of its inhabitants will be met. Naturally, this will include methods for growing food and seeing to the health, safety, transportation, and energy needs of the colonists.

In the future, the UAE also anticipates that uncrewed missions will be mounted to explore the surface of Mars and locate a possible site for the future colony. In short, they are not only joining the “Mars or Bust” club, but also the international community of space explorers.

Further Reading: Government of Dubai

Posted on by Matt Williams

Sad About Pluto? How about 110 Planets in the Solar System Instead?

Montage of every round object in the solar system under 10,000 kilometers in diameter, to scale. Credit: Emily Lakdawalla/data from NASA /JPL/JHUAPL/SwRI/SSI/UCLA/MPS/DLR/IDA/Gordan Ugarkovic/Ted Stryk, Bjorn Jonsson/Roman Tkachenko. Source

In 2006, during their 26th General Assembly, the International Astronomical Union (IAU) adopted a formal definition of the term “planet”. This was done in the hopes of dispelling ambiguity over which bodies should be designated as “planets”, an issue that had plagued astronomers ever since they discovered objects beyond the orbit of Neptune that were comparable in size to Pluto.

Needless to say, the definition they adopted resulted in fair degree of controversy from the astronomical community. For this reason, a team of planetary scientists – which includes famed “Pluto defender” Alan Stern – have come together to propose a new meaning for the term “planet”. Based on their geophysical definition, the term would apply to over 100 bodies in the Solar System, including the Moon itself.

The current IAU definition (known as Resolution 5A) states that a planet is defined based on the following criteria:

“(1) 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 neighbourhood around its orbit.

(2) A “dwarf 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 , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects , except satellites, orbiting the Sun shall be referred to collectively as “Small Solar-System Bodies”

Results of a study combining Kepler observations with Herschel data show that 2007 OR10 is the largest unnamed dwarf planet in our Solar System, and the third largest overall. Illustration: Konkoly Observatory/András Pál, Hungarian Astronomical Association/Iván Éder, NASA/JHUAPL/SwRI
The dwarf planets of the Solar System, arranged according to size. Credit: Konkoly Observatory/András Pál, Hungarian Astronomical Association/Iván Éder, NASA/JHUAPL/SwRI

Because of these qualifiers, Pluto was no longer considered a planet, and became known alternately as a “dwarf planet”, Plutiod, Plutino, Trans-Neptunian Object (TNO), or Kuiper Belt Object (KBO). In addition, bodies like Ceres, and newly discovered TNOs like Eris, Haumea, Makemake and the like, were also designated as “dwarf planets”. Naturally, this definition did not sit right with some, not the least of which are planetary geologists.

Led by Kirby Runyon – a final year PhD student from the Department of Earth and Planetary Sciences at Johns Hopkins University – this team includes scientists from the Southwest Research Institute (SwRI) in Boulder, Colorado; the National Optical Astronomy Observatory in Tuscon, Arizona; the Lowell Observatory in Flagstaff, Arizona; and the Department of Physics and Astronomy at George Mason University.

Their study – titled “A Geophysical Planet Definition“, which was recently made available on the Universities Space Research Association (USRA) website – addresses what the team sees as a need for a new definition that takes into account a planet’s geophysical properties. In other words, they believe a planet should be so-designated based on its intrinsic properties, rather than its orbital or extrinsic properties.

From this more basic set of parameters, Runyon and his colleagues have suggested the following definition:

“A planet is a sub-stellar mass body that has never undergone nuclear fusion and that has sufficient self-gravitation to assume a spheroidal shape adequately described by a triaxial ellipsoid regardless of its orbital parameters.”

The most iconic image from the New Horizon’s July 2015 flyby, showing Pluto’s ‘heart.’ Credit: NASA/JHUAPL/SwRI.

As Runyon told Universe Today in a phone interview, this definition is an attempt to establish something that is useful for all those involved in the study of planetary science, which has always included geologists:

“The IAU definition is useful to planetary astronomers concerned with the orbital properties of bodies in the Solar System, and may capture the essence of what a ‘planet’ is to them. The definition is not useful to planetary geologists. I study landscapes and how landscapes evolve. It also kind of irked me that the IAU took upon itself to define something that geologists use too.

“The way our brain has evolved, we make sense of the universe by classifying things. Nature exists in a continuum, not in discrete boxes. Nevertheless, we as humans need to classify things in order to bring order out of chaos. Having a definition of the word planet that expresses what we think a planet ought to be, is concordant with this desire to bring order out of chaos and understand the universe.”

The new definition also attempts to tackle many of the more sticky aspects of the definition adopted by the IAU. For example, it addresses the issue of whether or not a body orbits the Sun – which does apply to those found orbiting other stars (i.e. exoplanets). In addition, in accordance with this definition, rogue planets that have been ejected from their solar systems are technically not planets as well.

And then there’s the troublesome issue of “neighborhood clearance”. As has been emphasized by many who reject the IAU’s definition, planets like Earth do not satisfy this qualification since new small bodies are constantly injected into planet-crossing orbits – i..e Near-Earth Objects (NEOs). On top of that, this proposed definition seeks to resolve what is arguably one of the most regrettable aspects of the IAU’s 2006 resolution.

Artist’s impression of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. Credit: ESO/M. Kornmesser

“The largest motivation for me personally is: every time I talk about this to the general public, the very next thing people talk about is ‘Pluto is not a planet anymore’,” said Runyon. “People’s interest in a body seems tied to whether or not it has the name ‘planet’ labelled on it. I want to set straight in the mind of the public what a planet is. The IAU definition doesn’t jive with my intuition and I find it doesn’t jive with other people‘s intuition.”

The study was prepared for the upcoming 48th Lunar and Planetary Science Conference. This annual conference – which will be taking place this year from March 20th-24th at the Universities Space Research Association in Houston, Texas – will involve specialists from all over the worlds coming together to share the latest research findings in planetary science.

Here, Runyon and his colleagues hope to present it as part of the Education and Public Engagement Event. It is his hope that through an oversized poster, which is a common education tool at Lunar and Planetary Science Conference, they can show how this new definition will facilitate the study of the Solar System’s many bodies in a way that is more intuitive and inclusive.

“We have chosen to post this in a section of the conference dedicated to education,” he said. “Specifically, I want to influence elementary school teachers, grades K-6, on the definitions that they can teach their students. This is not the first time someone has proposed a definition other than the one proposed by the IAU. But few people have talked about education. They talk among their peers and little progress is made. I wanted to post this in a section to reach teachers.”

In accordance with the definition proposed by Runyon, bodies like Ceres and even the moon would be considered “planets”. Credit: NASA/ JPL/Planetary Society/Justin Cowart

Naturally, there are those who would raise concerns about how this definition could lead to too many planets. If intrinsic property of hydrostatic equilibrium is the only real qualifier, then large bodies like Ganymede, Europa, and the Moon would also be considered planets. Given that this definition would result in a Solar System with 110 “planets”, one has to wonder if perhaps it is too inclusive. However, Runyon is not concerned by these numbers.

“Fifty states is a lot to memorize, 88 constellations is a lot to memorize,” he said. “How many stars are in the sky? Why do we need a memorable number? How does that play into the definition? If you understand the periodic table to be organized based on the number of protons, you don’t need to memorize all the atomic elements. There’s no logic to the IAU definition when they throw around the argument that there are too many planets in the Solar System.”

Since its publication, Runyon has also been asked many times if he intends to submit this proposal to the IAU for official sanction. To this, Runyon has replied simply:

“No. Because the assumption there is that the IAU has a corner on the market on what a definition is. We in the planetary science field don’t need the IAU definition. The definition of words is based partly on how they are used. If [the geophysical definition] is the definition that people use and what teachers teach, it will become the de facto definition, regardless of how the IAU votes in Prague.”

Regardless of where people fall on the IAU’s definition of planet (or the one proposed by Runyon and his colleagues) it is clear that the debate is far from over. Prior to 2006, there was no working definition of the term planet; and new astronomical bodies are being discovered all the time that put our notions of what constitutes a planet to the test.  In the end, it is the process of discovery which drives classification schemes, and not the other way around.

Further Reading: USRA

Image Source: Planetary Society

Posted on by Tammy Plotner

Messier 35 – the NGC 2168 Open Star Cluster

The open star cluster Messier 35, with NGC 2158 and IC 2157 shown nearby. Credit: Wikisky

Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the open star cluster known as Messier 35. Enjoy!

During the 18th century, famed French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky. Having originally mistaken them for comets, he began compiling a list of them so that others would not make the same mistake he did. In time, this list (known as the Messier Catalog) would come to include 100 of the most fabulous objects in the night sky.

One of these objects is known as Messier 35, a large open star cluster located in the northern constellation Gemini. M35 is the only Messier Object located in Gemini, and lies near the border with the adjacent constellations of  Taurus, Auriga and Orion. It consists several hundred stars that are scattered over an area that is about the same size as a Full Moon.

What You Are Looking At:

Messier 35 is 2,800 light years away from Earth and is relatively young as star clusters go, having formed only about 100 million years ago. The cluster occupies a region of space that is roughly 24 light years in diameter, and an area of 28 arc minutes on the sky – which is roughly equal to the size of the full Moon.

Image of Messier 35 obtained by the Two Micron All Sky Survey (2MASS). Credit: NASA/2MASS

M35 has a central mass that spans 11.4 light years (3.75 parsecs), with an estimated mass of 1600 to 3200 solar masses. While most of the molecule cloud from which it formed has been blown away, some of the material resides in the immediate vicinity of its stars. This can be seen in the way that light from its particularly bright blue stars is scattered to create a diffuse glow.

These are the hottest main sequence stars in the cluster, which correspond to a spectral classification of B3. M35 also contains more evolved stars, including several orange and yellow giants, which have longer lifespans than the more-massive blue stars (only a few tense of millions of years).

As a result, these stars will likely die out in the near future while the smaller stars continue to evolve, drastically affecting the cluster’s luminosity and appearance. In short, it will become redder and dimmer over time.

History of Observation:

This wonderful star cluster was discovered by Philippe Loys de Chéseaux 1745-46 and recovered again by John Bevis before 1750. However, we know and love it best as Messier Object 35, when it was penned into being by Charles Messier. As he wrote of the cluster upon observing it for the first time:

“In the night of August 30 to 31, 1764, I have observed a cluster of very small stars, near the left foot of Castor, little distant from the stars Mu and Eta of that constellation [Gemini]. When examining this star cluster with an ordinary refractor of 3 feet, it seemed to contain nebulosity; but having examined it with a good Gregorian telescope which magnified 104 times, I have noticed that it is nothing but a cluster of small stars, among which there are some which are of more light; its extension may be 20 minutes of arc. I have compared the middle of this cluster with the star Eta of Castor; its right ascension has been concluded at 88d 40′ 9″, and its declination at 24d 33′ 30″ north.”

Close-up of the Messier 35 open star cluster, showing its blue stars. Credit: Wikisky

How long would it be before the companion cluster was observed as well? My guess is Sir William Herschel’s time. Although Herschel would not publish his notes on Messier objects, they do state while observing M35 that “There is no central condensation to denote a globular form.”

And what of Admiral Smyth? He observed the cluster in September of 1836, though he appeared to have missed its companion cluster. As he recorded of M35 at the time:

“A cluster, near Castor’s right foot, in the Galaxy, discovered and registered by Messier in 1764. It presents a gorgeous field of stars from the 9th to the 16th magnitudes, but with the center of mass less rich than the rest. From the small stars being inclined to form curves of three, four, and often with a large [bright] one at the root of the curve, it somewhat reminds one of the bursting of a sky-rocket.”

A nice description, but if you see the companion cluster, you’ll know it!

Locating Messier 35:

Locating M35 in binoculars is fairly easy once you recognize the constellation of Gemini. You’ll find it just a little more than the average field of view north of Eta – the center most of the three “foot” stars on the northernmost twin. In the finderscope of a telescope, begin with Eta and starhop north until you spot a faint fuzzy in the finderscope.

The location of Messier 35 in the norther n Gemini constellation. Credit: IAU/Sky & Telescope magazine/Roger Sinnott & Rick Fienberg

Because Messier 35 is large, you’ll need low magnification to appreciate the size of this cluster in a telecope. It stands up well to moonlight and light polluted skies – as well as less than perfect sky conditions, but you will need around a 10″ or larger telescope to really begin to notice its companion cluster, NGC 2158. In smaller telescopes with good conditions, it will appear as a faint nebulous patch.

And as always, here are the quick facts on M35 to get you started!

Object Name: Messier 35
Alternative Designations: M35, NGC 2168
Object Type: Galactic Open Star Cluster
Constellation: Gemini
Right Ascension: 06 : 08.9 (h:m)
Declination: +24 : 20 (deg:m)
Distance: 2.8 (kly)
Visual Brightness: 5.3 (mag)
Apparent Dimension: 28.0 (arc min)

We have written many interesting articles about Messier Objects here at Universe Today. Here’s Tammy Plotner’s Introduction to the Messier Objects, , M1 – The Crab Nebula, M8 – The Lagoon Nebula, and David Dickison’s articles on the 2013 and 2014 Messier Marathons.

Be to sure to check out our complete Messier Catalog. And for more information, check out the SEDS Messier Database.

Sources:

Posted on by Matt Williams

Juno Will Get No Closer To Jupiter Due To Engine Troubles

Jupiter’s south pole. captured by the JunoCam on Feb. 2, 2017, from an altitude of about 62,800 miles (101,000 kilometers) above the cloud tops. Credits: NASA/JPL-Caltech/SwRI/MSSS/John Landino

On July 4th, 2016, the Juno mission established orbit around Jupiter, becoming the second spacecraft in history to do so (after the Galileo probe). Since then, the probe has been in a regular 53.4-day orbit (known as perijove), moving between the poles to avoid the worst of its radiation belts. Originally, Juno’s mission scientists had been hoping to reduce its orbit to a 14-day cycle so the probe could make more passes to gather more data.

To do this, Juno was scheduled for an engine burn on Oct. 19th, 2016, during its second perijovian maneuver. Unfortunately, a technical error prevented this  from happening. Ever since, the mission team has been pouring over mission data to determine what went wrong and if they could conduct an engine burn at a later date. However, the mission team has now concluded that this won’t be possible.

The technical glitch which prevented the firing took place weeks before the engine burn was scheduled to take place, and was traced to two of the engines helium check valves. After the propulsion system was pressurized, the valves took several minutes to open – whereas they took only seconds during previous engine burns. Because of this, the mission leaders chose to postpone the firing until they could get a better understanding of why the glitch happened.

This amateur-processed image was taken on Dec. 11th, 2016, at 9:27 a.m. PST (12:27 p.m. EST), as NASA’s Juno spacecraft performed its third close flyby of Jupiter. Credits: NASA/JPL-Caltech/SwRI/MSSS/Eric Jorgensen

And after pouring over mission data from the past few months and performing calculations on possible maneuvers, Juno’s science team came to the conclusion that an engine burn might be counter-productive at this point. As Rick Nybakken, the Juno project manager at NASA’s Jet Propulsion Laboratory (JPL), explained in a recent NASA press release:

“During a thorough review, we looked at multiple scenarios that would place Juno in a shorter-period orbit, but there was concern that another main engine burn could result in a less-than-desirable orbit. The bottom line is a burn represented a risk to completion of Juno’s science objectives.”

However, this is not exactly bad news for the mission. It’s current perijove orbit takes it from one pole to the other, allowing it to pass over the cloud tops at a distance of around 4,100 km (2,600 mi) at its closest. At its farthest, the spacecraft reaches a distance of 8.1 million km (5.0 million mi) from the gas giant, which places it far beyond the orbit of Callisto.

During each pass, the probe is able to peak beneath the thick clouds to learn more about the planet’s atmosphere, internal structure, magnetosphere, and formation. And while a 14-day orbital period would allow for it to conduct 37 orbits before its mission is scheduled to wrap up, its current 53.4-day period will allow for more information to be collected on each pass.

And as Thomas Zurbuchen, the associate administrator for NASA’s Science Mission Directorate in Washington, declared:

“Juno is healthy, its science instruments are fully operational, and the data and images we’ve received are nothing short of amazing. The decision to forego the burn is the right thing to do – preserving a valuable asset so that Juno can continue its exciting journey of discovery.”

In the meantime, the Juno science team is still analyzing the returns from Juno’s four previous flybys – which took place on August 27th, October 19th, December 11th, and February 2nd, 2017, respectively. With each pass, more information is revealed about the planet’s magnetic fields, aurorae, and banded appearance. The next perijovian maneuver will take place on March 27th, 2017, and will result in more images and data being collected.

Before the mission concludes, the Juno spacecraft will also explore Jupiter’s far magnetotail, its southern magnetosphere, and its magnetopause. The mission is also conducting an outreach program with its JunoCam, which is being guided with assistance of the public. Not only can people vote on which features they want imaged with every flyby, but these images are accessible to “citizen scientists” and amateur astronomers.

Under its current budget plan, Juno will continue to operate through to July 2018, conducting a total of 12 science orbits. At this point, barring a mission extension, the probe will be de-orbited and burn up in Jupiter’s outer atmosphere. As with the Galileo spacecraft, this will be as to avoid any possibility of impact and biological contamination with one of Jupiter’s moons.

Further Reading: NASA

Posted on by Bob King

A Region On Mars With Recent Water Is About To Get Major Attention

Credit: NASA/ JPL-Caltech
Striations exposed on the surface between Martian sand dunes (one pictured at top) in Lucaya Crater indicate fluctuating levels of salty groundwater. At “a” we see possible cross beds which are tilted layers of sand within larger layers deposited by wind or water. At b, dark and light strata are similar to that exposed in the dune at top and resemble the striations seen in the Namib Desert on Earth. The photo was taken by NASA’s Mars Reconnaissance Orbiter in infrared, red and blue light. Credit: NASA/JPL-Caltech

Researcher Dr. Mary Bourke from Trinity College Dublin have discovered a patch of land in an ancient valley in Mars’ Lucaya Crater that appears to have held water in the not-too-distant past, making it a prime target to search for past life forms on the Red Planet. Signs of water past and present pop up everywhere on Mars from now-dry, wriggly riverbeds snaking across arid plains to water ice exposed at the poles during the Martian summer.

A valley lined with sand dunes crosses the southern floor of the 21-mile-wide Lucaya Crater, located at latitude 11° south and longitude 52° east on Mars. Striations found between the dunes may have been created by recent water flows. The box shows the area pictured in the close up above. The 3.7-mile-long valley measures between 2,000 and 2,600 feet wide. Credit: NASA/JPL-Caltech with additions by the author

On Earth, Bourke had done previous studies of dunes in the Namib Desert near Walvis Bay, Namibia and noted “arctuate striations” — crusty arcs of sand cemented by water and minerals — on the surfaces of migrating sand dunes using photos taken by satellite. She subsequently assembled a team to check them out on the ground and discovered that the striations resulted when dune materials had been chemically cemented by salts left behind by evaporating groundwater.

“On Earth, desert dune fields are periodically flooded by water in areas of fluctuating groundwater, and where lakes, rivers and coasts are found in proximity,” said Bourke. These periodic floods leave tell-tale patterns behind them.” Once the material had been cemented, it hardens and remains behind as the dunes continue to migrate downwind.

Compare these cemented arctuate striations between dunes near Walvis Bay, Namibia with those in Lucaya Crater’s valley in the earlier image. White arrows highlight particularly prominent examples. Photos in (b) and (c) were taken from the ground. The excavated pit in (c) shows that the dipping sediment layers below the surface match the protruding layers on the surface. Alternating light and dark layers have different salt composition and grain size. Credit: Google Earth (left) and Dr Mary Bourke, Trinity College Dublin

Next, Bourke and colleague Prof. Heather Viles, from the University of Oxford, examined close up images of Mars taken with the Mars Reconnaissance Orbiter (MRO) and experienced a flash of insight: “You can imagine our excitement when we scanned satellite images of an area on Mars and saw this same patterned calling card, suggesting that water had been present in the relatively recent past.”

Bourke examined similar arcuate striations exposed on the surface between dunes, indications of fluctuating levels of salty groundwater during a time when dunes were actively migrating down the valley.

A possible scenario: an asteroid impacts Mars, forming Lucaya Crater and unleashing water flows that created the crater valley and striations.

So where did the water come from to create the striations in the crater valley? Bourke and Viles propose that water may have been released by the impact that formed Lucaya Crater especially if the target area was rich in ice.

Extreme temperatures during the impact would have vaporized water but also possibly melted other ice to flow for a time as liquid water. Alternatively, the impact may have jump-started hydrothermal activity as hot springs-style underground flows.

Flowing water would have created the valley and saturated the soils there with salty water. In dry periods, erosion from the wind would have picked away the water-eroded sands to create the striking pattern of repeating dunes we see to this day.

Water, water everywhere … once upon a time. Nanedi Valles, a roughly 500-mile-long (800 km) valley extending southwest-northeast and photographed by Mars Express. In this view, Nanedi Valles ranges from approximately 0.5 – 3 miles (0.8- to 5.0 km) wide and extends to a maximum of about 1,640 feet (500 meters) below the surrounding plains. The valley’s origins remain unclear, with scientists debating whether erosion caused by ground-water outflow, flow of liquid beneath an ice cover or collapse of the surface in association with liquid flow is responsible. In all cases, it’s clear that water was involved. Copyright ESA/DLR/FU Berlin (G. Neukum)

Carbonate rocks, which require liquid water to form are dissolved by the same, have been detected in the valley using spectroscopy and could have served as the cement to solidify sands between the moving dunes. That in concert with alternating dry and wet periods would create the striations seen in the MRO photos.

“These findings are hugely significant,” said Bourke. “Firstly, the Martian sand dunes show evidence that water may have been active near Mars’ equator — potentially in the not-too-distant past. And secondly, this location is now a potential geological target for detecting past life forms on the Red Planet, which is important to those involved in selecting sites for future missions.”

Posted on by Matt Williams

Ceres Provides First Detection Of Life’s Building Blocks In Asteroid Belt

Enhanced color-composite image, made with data from the framing camera aboard NASA's Dawn spacecraft, shows the area around Ernutet crater. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

NASA’s Dawn spacecraft has been poking around Ceres since it first established orbit in March of 2015. In that time, the mission has sent back a steam of images of the minor planet, and with a level of resolution that was previously impossible. Because of this, a lot of interesting revelations have been made about Ceres’ composition and surface features (like its many “bright spots“).

In what is sure to be the most surprising find yet, the Dawn spacecraft has revealed that Ceres may actually possess the ingredients for life. Using data from the Dawn spacecraft’s Visible and InfraRed Mapping Spectrometer (VIMS), an international team of scientists has confirmed the existence of organic molecules on Ceres – a find which could indicate that it has conditions favorable to life.

These findings – which were detailed in a study titled “Localized aliphatic organic material on the surface of Ceres” – appeared in the Feb. 17th, 2017, issue of Science. For the sake of their study, the international team of researchers – which was led by Maria Cristina de Sanctis from the National Institute of Astrophysics in Rome, Italy – showed how Dawn sensor data pointed towards the presence of aliphatic compounds on the surface.

Enhanced color-composite image from Dawn’s visible and infrared mapping spectrometer, showing the area around Ernutet Crater on Ceres. Credit: NASA/JPL-Caltech/UCLA/ASI/INAF

Aliphatics are a type of organic compound where carbon atoms form open chains that are commonly bound with oxygen, nitrogen, sulfur and chlorine. The least complex aliphatic is methane, which has been detected in many locations across the Solar System – including in the Martian atmosphere and in both liquid and gaseous form on Saturn’s moon Titan.

From their study, Dr. de Sanctis and her colleagues determined that spectral data obtained by the VIMS instrument corresponded to the presence of these hydrocarbons in a region outside of the Ernutet crater. This crater, which is located in the northern hemisphere of Ceres, measures about 52 km (32 mi) in diameter. The aliphatic compounds which were detected were localized in a roughly 1000 square kilometers region around it.

The team ruled out the possibility that these organic molecules were deposited from an external source – such as a comet or carbonaceous chondrite asteroid. While both have been shown to contain organic molecules in their interior in the past, the largest concentrations on Ceres were distributed discontinuously across the southwest floor and rim of the Ernutet crater and onto an older, highly degraded crater.

In addition, other organic-rich areas were spotted being are scattered to the northwest of the crater. As Dr.  Maria Cristina De Sanctis told Universe Today via email:

“The composition that we see on Ceres is similar to some meteorites that has organics and thus we searched for this material. We considered both endogenous and exogenous origin, but the last one seems less likely due to several reasons including the larger abundance observed on Ceres with respect the meteorites.”

Dawn spacecraft data, showing the organics absorption band (warmer colors indicate highest concentrations). Credit: NASA/JPL-Caltech/UCLA/ASI/INAF/MPS/DLR/IDA

Instead, they considered the possibility that they organic molecules were endogenous in origin. In the past, surveys have shown evidence of hydrothermal activity on Ceres, which included signs of surface renewal and fluid mobility. Combined with other surveys that have detected ammonia-bearing hydrated minerals, water ice, carbonates, and salts, this all points towards Ceres having an environment that can support prebiotic chemistry.

“The overall composition of Ceres can favor the pre-biotic chemistry,” said De Sanctis. “Ceres has water ice and minerals (carbonates and phyllosilicates) derived  from pervasive aqueous  alteration of rocks. It has also material that we think is formed in hydrothermal environments.  All these information indicate condition not hostel to biotic molecules.”

These findings are certainly significant in helping to determine if life could exist on Ceres – in a way that is similar to Europa and Enceladus, locked away beneath its icy mantle. But given that Ceres is believed to have originated 4.5 billion years ago (when the Solar System was still in the process of formation), this study is also significant in that it can shed light on the origin, evolution, and distribution of organic life in our the Solar System.

Other members of the research team include researchers from the department of Earth Planetary and Space Sciences at the University of California, the Department of Earth and Planetary Sciences at the University of Tennessee, the Department of Earth, Environmental, and Planetary Sciences at Brown University, the Southwest Research Institute (SwRI), the NASA Goddard Space Flight Center, and NASA’s Jet Propulsion Laboratory.

Further Reading: ScienceMag, SwRI

Posted on by Matt Williams

What is the Weather like on Saturn?

The Saturn hexagon as seen by Voyager 1 in 1980 (NASA)

Welcome back to our planetary weather series! Next up, we take a look at the ringed-beauty, Saturn!

Saturn is famous for many things. Aside from its ring system, which are the most visible and beautiful of any gas giant, it is also known for its extensive system of moons (the second largest in the Solar System behind Jupiter). And then there its banded appearance and gold color, which are the result of its peculiar composition and persistent weather patterns.

Much like Jupiter, Saturn’s weather systems are known for being particularly extreme, giving rise to features that can be seen from great distances. It’s high winds periodically create massive oval-shaped storms, jet streams, hurricanes, and hexagonal wave patterns that are visible in both the northern and southern polar regions.

Saturn’s Atmosphere:

The outer atmosphere of Saturn contains 96.3% molecular hydrogen and 3.25% helium by volume. The gas giant is also known to contain heavier elements, though the proportions of these relative to hydrogen and helium is not known. It is assumed that they would match the primordial abundance from the formation of the Solar System.

The huge storm churning through the atmosphere in Saturn’s northern hemisphere overtakes itself as it encircles the planet in this true-color view from NASA’s Cassini spacecraft. Credit: NASA/JPL-Caltech/SSI

Trace amounts of ammonia, acetylene, ethane, propane, phosphine and methane have been also detected in Saturn’s atmosphere. The upper clouds are composed of ammonia crystals, while the lower level clouds appear to consist of either ammonium hydrosulfide (NH4SH) or water. Ultraviolet radiation from the Sun causes methane photolysis in the upper atmosphere, leading to a series of hydrocarbon chemical reactions with the resulting products being carried downward by eddies and diffusion.

Saturn’s atmosphere exhibits a banded pattern similar to Jupiter’s, but Saturn’s bands are much fainter and wider near the equator. As with Jupiter’s cloud layers, they are divided into the upper and lower layers, which vary in composition based on depth and pressure. In the upper cloud layers, with temperatures in range of 100–160 K and pressures between 0.5–2 bar, the clouds consist of ammonia ice.

The presence of hydrogen gas results in clouds of deep red. However, these are obscured by clouds of ammonia, which are closer to the outer edge of the atmosphere and cover the entire planet. The exposure of this ammonia to the Sun’s ultraviolet radiation causes it to appear white. Combined with its deeper red clouds, this results in the planet having a pale gold color.

Water ice clouds begin at a level where the pressure is about 2.5 bar and extend down to 9.5 bar, where temperatures range from 185–270 K. Intermixed in this layer is a band of ammonium hydrosulfide ice, lying in the pressure range 3–6 bar with temperatures of 290–235 K. Finally, the lower layers, where pressures are between 10–20 bar and temperatures are 270–330 K, contains a region of water droplets with ammonia in an aqueous solution.

Great White Spot:

On occasion, Saturn’s atmosphere exhibits long-lived ovals, similar to what is commonly observed on Jupiter. Whereas Jupiter has the Great Red Spot, Saturn periodically has what’s known as the Great White Spot (aka. Great White Oval). This unique but short-lived phenomenon occurs once every Saturnian year, roughly every 30 Earth years, around the time of the northern hemisphere’s summer solstice.

These spots can be several thousands of kilometers wide, and have been observed in 1876, 1903, 1933, 1960, and 1990. Since 2010, a large band of white clouds called the Northern Electrostatic Disturbance have been observed enveloping Saturn, which was spotted by the Cassini space probe. If the periodic nature of these storms is maintained, another one will occur in about 2020.

Meteorological Phenomena:

The winds on Saturn are the second fastest among the Solar System’s planets, after Neptune’s. This is due in part to Saturn’s high rotational velocity – which is 9.87 km/s (6.13 mi/s), which works out to 35,500 km/h (22,058.7 mi/h). At this rate, it only takes the planet 10 hours 33 minutes to rotate once on its axis. However, due to it being a gas giant, there is a difference between the rotation of its atmosphere and its core.

Data obtained by the Voyager 1 and 2 missions indicated peak easterly winds of 500 m/s (1800 km/h). Saturn’s northern and southern poles have also shown evidence of stormy weather. At the north pole, this takes the form of a hexagonal wave pattern, whereas the south shows evidence of a massive jet stream.

Saturn makes a beautifully striped ornament in this natural-color image, showing its north polar hexagon and central vortex. Credit: NASA/JPL-Caltech/Space Science Institute

The persisting hexagonal wave pattern around the north pole was first noted in the Voyager images. The sides of the hexagon are each about 13,800 km (8,600 mi) long (which is longer than the diameter of the Earth) and the structure rotates with a period of 10h 39m 24s, which is assumed to be equal to the period of rotation of Saturn’s interior.

The south pole vortex, meanwhile, was first observed using the Hubble Space Telescope. These images indicated the presence of a jet stream, but not a hexagonal standing wave. These storms are estimated to be generating winds of 550 km/h, are comparable in size to Earth, and believed to have been going on for billions of years.

In 2006, the Cassini space probe observed a hurricane-like storm that had a clearly defined eye. Such storms had not been observed on any planet other than Earth – even on Jupiter. This storm appeared to be caused by heat that was generated in the depths of the warm interior of Saturn, which then escaped to the upper atmosphere and escaped the planet.

Saturn has also been noted for its “string of pearls” feature, which was captured by Cassini’s visual and infrared mapping spectrometer in 2006. This feature, which appeared in it’s northern latitudes (and has not been seen on any other gas giant) is a series of cloud clearings spaced at regular intervals that show how Saturn’s atmosphere is lit by its own internal, thermal glow.

So how is the weather on Saturn? Pretty violent and stormy! And not surprising given the planet’s mass, composition, powerful gravity, and rapid rotation. Makes you feel happy we live on Earth, where the Earth is (comparatively speaking) pretty calm and boring!

We have written many interesting articles about planetary weather here at Universe Today. Here’s What’s the Weather Like on Mercury?, What’s the Weather Like on Venus?, What’s the Weather Like on Mars?, What’s the Weather Like on Jupiter?, What is the Weather Like on Uranus? and What is the Weather Like on Neptune?

For more information, check out NASA’s Solar System Exploration – Saturn, and the facts about Saturn from Space Facts.

Astronomy Cast has recorded some interesting episode on the subject. Here’s Episode 59: Saturn, and Episode 61: Saturn’s Moons.

Sources:

Posted on by Bob King

Video of Green Comet 45P Puts You Close To The Action

Comet 45P is seen here on Feb. 8, 2017. The comet appears very spread out and diffuse. While its overall brightness is about magnitude +8.5, the comet appears diffuse and faint. Credit: Chris Schur
This animation of comet 45P/H-M-P is composed of thirteen delay-Doppler images made during 2 hours of observation using the Arecibo Observatory on Feb. 12. Credit: USRA

Comets hide their central engines well. From Earth, we see a bright, fuzzy coma and a tail or two. But the nucleus, the source of all the hubbub, remains deeply camouflaged by dust, at best appearing like a blurry star.

To see one up close, you need to send a spacecraft right into the comet’s coma and risk getting. Or you can do the job much more cheaply by bouncing radio waves off the nucleus and studying the returning echoes to create a shadowy image.

Although crude compared to optical photos of moons and planets, radar images reveal much about an asteroid including surface details like mountains, craters, shape and rotation rate. They’re also far superior to what optical telescopes can resolve when it comes to asteroids, which, as their name implies, appear star-like or nearly so in even large professional telescopes.

On Feb. 11, green-glowing comet 45P/Honda-Mrkos-Pajdusakova, made an unusually close pass of Earth, zipping just 7.7 million miles away. Astronomers made the most of the encounter by pressing the huge 1,000-foot-wide (305 meters) Arecibo radio dish into service to image the comet’s nucleus during and after closest approach.

Arecibo Observatory, the world’s biggest single dish radio telescope, was and is still being used to image comet 45P/H-M-P. Courtesy of the NAIC – Arecibo Observatory, a facility of the NSF

“The Arecibo Observatory planetary radar system can pierce through the comet’s coma and allows us to study the surface properties, size, shape, rotation, and geology of the comet nucleus”, said Dr. Patrick Taylor, USRA Scientist and Group Lead for Planetary Radar at Arecibo.

The two lobes of comet 67P/C-G stand out clearly in this photo taken by ESA’s Rosetta spacecraft while in orbit about the comet on March 6, 2015. Credit: ESA/Rosetta

Does the shape ring a bell? Remember Rubber Ducky? It doesn’t take a rocket scientist to see that the comet’s heart resembles the twin-lobed comet 67P/Churyumov-Gerasimenko orbited by ESA’s Rosetta spacecraft. Using the dish, astronomers have seen bright regions and structures on the comet; they also discovered that the nucleus is a little larger than expected with a diameter of 0.8 mile (1.3 km) and rotates about once every 7.6 hours. Go to bed at 10 and wake up at 6 and the comet will have made one complete turn.

Comet 45P is seen here on Feb. 8, 2017. While its overall brightness is about magnitude +8.5, the comet appears diffuse and rather faint. From dark skies, it remains a binocular object at least for a little while. Credit: Chris Schur

Radio observations of 45P/H-M-P will continue through Feb. 17. Right now, the comet is happily back in the evening sky and still visible with 10×50 or larger binoculars around 10-11 p.m. local time in the east. I spotted it low in Bootes last night about 15 minutes before moonrise under excellent, dark sky conditions. It looked like a faint, smoky ball nearly as big as the full moon or about 30 arc minutes across.

This week, the pale green blob (the green’s from fluorescing carbon), vaults upward from Bootes, crosses Canes Venatici and zooms into Coma Berenices. For maps to help you track and find it night by night, please click here. I suggest larger binoculars 50mm and up or a 6-inch or larger telescope. Be sure to use low power — the comet’s so big, you need a wide field of view to get dark sky around it in order to see it more clearly.

Very few comets pass near Earth compared to the number of asteroids that routinely do. That’s one reason 45P is only the seventh imaged using radar; rarely are we treated to such detailed views!

Posted on by Matt Williams

India Sets Record With 104 Satellites In Single Launch

The thirty-ninth flight of the ISRO's Polar Satellite Launch Vehicle (PSLV-C37), which successfully from Satish Dhawan Space Centre SHAR, Sriharikota on February 15th, 2017. Credit: ISRO

India’s national space agency – the Indian Space Research Organization (ISRO) – has come a long way in recent years. In 2008, the agency launched its first lunar explorer, Chandrayaan-1, which also deployed a lander (the Moon Impact Probe) to the surface. And then there was the Mangalayaan mission – aka. the Mars Orbiter Mission (MOM) – which made history on Sept. 24th, 2014, when it became the first probe to enter orbit around Mars on the first try.

In their latest feat, the ISRO established a new record for the number of satellites launched in a single mission. In what was the thirty-ninth launch of the Polar Satellite Launch Vehicle (PSLV), the organization deployed 104 satellites into orbit. In so doing, they have effectively overtaken the previous record of 37 – which was established by Roscosmos in June of 2014.

This launch was also the thirty eighth successful mission in a row for the PSLV. which has been in service since the early 1990s. Prior to this flight, the rocket had successfully launched a total of 71 satellites and spacecraft – 31 of which were Indian – into a variety of orbits. The most satellites it launched at one time was 20, which took place on June 22nd, 2016, with the launch of the PSLV-C34 mission.

The thirty-sixth launch of the ISROs India’s Polar Satellite Launch Vehicle (PSLV-C34), in June 2016. Credit: ISRO

Hence, it has not only beaten its own record this single launch (and by a factor of five, no less), but more than doubled the total amount of satellites it has deployed. This mission also pushed the total number of Indian-made satellites sent into space aboard the PSLV rocket to 46, and the number of customer satellites that India has launched to 180.

As the ISRO reported shortly after the launch:

“PSLV-C37 lifted off at 0928 hrs (9:28 am) IST, as planned, from the First Launch Pad. After a flight of  16 minutes 48 seconds, the satellites achieved a polar Sun Synchronous Orbit of 506 km inclined at an angle of 97.46 degree to the equator (very close to the intended orbit) and in the succeeding 12 minutes, all the 104 satellites successfully separated from the PSLV fourth stage in a predetermined sequence beginning with Cartosat-2 series satellite, followed by INS-1 and INS-2.”

Shortly after the launch, Prime Minister Narendra Modi, took to Twitter to congratulate the scientists and laud the space agency for its record-breaking accomplishment. “This remarkable feat by @isro is yet another proud moment for our space scientific community and the nation. India salutes our scientists,” he tweeted. “Congratulations to @isro for the successful launch of PSLV-C37 and CARTOSAT satellite together with 103 nano satellites!”

A Cartosat-2 Series Satellite undergoing a panel deployment test at ISAC Bengaluru. Credit: ISRO

The cargo consisted of a Cartosat-2 Series Satellite, which is the latest in a series of ISRO Earth-observation satellites. In the coming days, the satellite will position itself and begin to provide remote sensing services using its state-of-the-art panchromatic (PAN) camera – which takes black and white pictures of the Earth in the visible and EM spectrum – and its multi-spectral (color) cameras.

In addition, two technology demonstration satellites from India were deployed – the Nano Satellite-1 (INS-1) and INS-2. The remaining 101 co-passenger satellites were all the property of the ISRO’s international customers – with 96 coming from the US, and five coming from the Netherlands, Switzerland, Israel, Kazakhstan and the United Arab Emirates, respectively.

In addition to demonstrating the capability of India’s launch workhorse, this latest mission also shows the growing importance countries like India play in the modern space age. In the coming years, the ISRO hopes to commence its proposed human spaceflight program, which if successful will make it the fourth nation to conduct crewed missions to space (alongside NASA, Roscosmos, and China).

And be sure to check out the video below for footage of the PSLV-C37 mission’s liftoff and on-board camera video:

Further Reading: ISRO