ESO’s La Silla Observatory Over The Night Sky

Scientists push back against Harvard 'alien spacecraft' theory

This photo released by the European Southern Observatory on November 20, 2017 shows an artist’s impression of the first interstellar object known to enter our solar system: ‘Oumuamua

A scientific paper led by two researchers at Harvard University made a splash this week by claiming that a cigar-shaped rock zooming through our solar system may have been sent by aliens.

The researchers noted in a pre-print of the article that it was an “exotic scenario,” but that “Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization.”

Oumuamua, the first interstellar object known to enter our solar system, accelerated faster away from the Sun than expected, hence the notion that some kind of artificial sail that runs on sunlight—known as a light sail—may have helped push it through space.

“Currently there is an unexplained phenomena, namely, the excess acceleration of Oumuamua, which we show may be explained by the force of radiation pressure from the sun,” co-author and Harvard astrophysicist Shmuel Bialy told AFP via email Tuesday.

“However this requires the body to have a very large surface and be very thin, which is not encountered in nature.”

Their suggestion of an alien force at work went viral.

But other astronomy experts aren’t buying it.

“Like most scientists, I would love there to be convincing evidence of alien life, but this isn’t it,” said Alan Fitzsimmons, an astrophysicist at Queens University, Belfast.

“It has already been shown that its observed characteristics are consistent with a comet-like body ejected from another star system,” he told AFP.

“And some of the arguments in this study are based on numbers with large uncertainties.”

Read more ~ phys.org

A photo released by the European Space Agency on June 27, 2018 shows an artist’s impression of ‘Oumuamua Editor’s note: Any cometary outgassing required to provide acceleration would have been detectable. None detected. What kills the alien probe theory for me is it’s velocity. Fast enough to buzz through the solar system without being snared by the sun but WAY too slow for practical interstellar travel although it’s trajectory put it on a nice path for exploration.

Credit : NASA - https://www.nasa.gov/feature/jpl/small-asteroid-or-comet-visits-from-beyond-the-solar-system, Public Domain, https://commons.wikimedia.org/w/index.php?curid=64030370

10 Steps to Confirm a Planet Around Another Star

So you think you found an exoplanet – a planet around another star? It’s not as simple as pointing a telescope to the sky and looking for a planet that waves back. Scientists gather many observations and carefully analyze their data before they can be even somewhat sure that they’ve discovered new worlds.

Here are 10 things to know about finding and confirming exoplanets.

This is an illustration of the different elements in our exoplanet program, including ground-based observatories, like the W. M. Keck Observatory, and space-based observatories like Hubble, Spitzer, Kepler, TESS, James Webb Space Telescope, WFIRST and future missions.

1. Pick your tool to take a look.

The vast majority of planets around other stars have been found through the transit method so far. This technique involves monitoring the amount of light that a star gives off over time, and looking for dips in brightness that may indicate an orbiting planet passing in front of the star.

We have two specialized exoplanet-hunting telescopes scanning the sky for new planets right now – Kepler and the Transiting Exoplanet Survey Satellite (TESS) – and they both work this way. Other methods of finding exoplanets include radial velocity (looking for a “wobble” in a star’s position caused by a planet’s gravity), direct imaging (blocking the light of the star to see the planet) and microlensing (watching for events where a star passes in front of another star, and the gravity of the first star acts as a lens).

Here’s more about finding exoplanets.

2. Get the data.

To find a planet, scientists need to get data from telescopes, whether those telescopes are in space or on the ground. But telescopes don’t capture photos of planets with nametags. Instead, telescopes designed for the transit method show us how brightly thousands of stars are shining over time. TESS, which launched in April and just began collecting science data, beams its stellar observations back to Earth through our Deep Space Network, and then scientists get to work.

3. Scan the data for planets.

Researchers combing through TESS data are looking for those transit events that could indicate planets around other stars. If the star’s light lessens by the same amount on a regular basis – for example, every 10 days – this may indicate a planet with an orbital period (or “year”) of 10 days. The standard requirement for planet candidates from TESS is at least two transits – that is, two equal dips in brightness from the same star.

4. Make sure the planet signature couldn’t be something else.

Not all dips in a star’s brightness are caused by transiting planets. There may be another object – such as a companion star, a group of asteroids, a cloud of dust or a failed star called a brown dwarf, that makes a regular trip around the target star. There could also be something funky going on with the telescope’s behavior, how it delivered the data, or other “artifacts” in data that just aren’t planets. Scientists must rule out all non-planet options to the best of their ability before moving forward.

5. Follow up with a second detection method.

Finding the same planet candidate using two different techniques is a strong sign that the planet exists, and is the standard for “confirming” a planet. That’s why a vast network of ground-based telescopes will be looking for the same planet candidates that TESS discovers. It is also possible that TESS will spot a planet candidate already detected by another telescope in the past. With these combined observations, the planet could then be confirmed. The first planet TESS discovered, Pi Mensae c, orbits a star previously observed with the radial-velocity method on the ground. Scientists compared the TESS data and the radial-velocity data from that star to confirm the presence of planet “c.”

Scientists using the radial-velocity detection method see a star’s wobble caused by a planet’s gravity, and can rule out other kinds of objects such as companion stars. Radial-velocity detection also allows scientists to calculate the mass of the planet.

6. …or at least another telescope.

Other space telescopes may also be used to help confirm exoplanets, characterize them and even discover additional planets around the same stars. If the planet is detected by the same method, but by two different telescopes, and has received enough scrutiny that the scientists are more than 99 percent sure it’s a planet, it is said to be “validated” instead of “confirmed.”

7. Write a paper.

After thoroughly analyzing the data, and running tests to make sure that their result still looks like the signature of a planet, scientists write a formal paper describing their findings. Using the transit method, they can also report the size of the planet. The planet’s radius is related to how much light it blocks from the star, as well as the size of the star itself. The scientists then submit the study to a journal.

8. Wait for peer review.

Scientific journals have a rigorous peer review process. This means scientific experts not involved in the study review it and make sure the findings look sound. The peer-reviewers may have questions or suggestions for the scientists. When everyone agrees on a version of the study, it gets published.

9. Publish the study.

When the study is published, scientists can officially say they have found a new planet. This may still not be the end of the story, however. For example, the TRAPPIST telescope in Chile first thought they had discovered three Earth-size planets in the TRAPPIST-1 system. When our Spitzer Space Telescope and other ground-based telescopes followed up, they found that one of the original reported planets (the original TRAPPIST-1d) did not exist, but they discovered five others –bringing the total up to seven wondrous rocky worlds.

10. Catalog and celebrate – and look closer if you can!

Confirmed planets get added to our official catalog. So far, Kepler has sent back the biggest bounty of confirmed exoplanets of any telescope – more than 2,600 to date. TESS, which just began its planet search, is expected to discover many thousands more. Ground-based follow-up will help determine if these planets are gaseous or rocky, and possibly more about their atmospheres. The forthcoming James Webb Space Telescope will be able to take a deeper look at the atmospheres of the most interesting TESS discoveries.

Scientists sometimes even uncover planets with the help of people like you: exoplanet K2-138 was discovered through citizen scientists in Kepler’s K2 mission data. Based on surveys so far, scientists calculate that almost every star in the Milky Way should have at least one planet. That makes billions more, waiting to be found! Stay up to date with our latest discoveries using this exoplanet counter.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

(Source)

Neptune ♆

On this day in 1846 was discovered the planet Neptune.

The ice giant Neptune was the first planet located through mathematical predictions rather than through regular observations of the sky. (Galileo had recorded it as a fixed star during observations with his small telescope in 1612 and 1613.) When Uranus didn’t travel exactly as astronomers expected it to, a French mathematician, Urbain Joseph Le Verrier, proposed the position and mass of another as yet unknown planet that could cause the observed changes to Uranus’ orbit. After being ignored by French astronomers, Le Verrier sent his predictions to Johann Gottfried Galle at the Berlin Observatory, who found Neptune on his first night of searching in 1846. Seventeen days later, its largest moon, Triton, was also discovered.

Neptune is invisible to the naked eye because of its extreme distance from Earth. Interestingly, the highly eccentric orbit of the dwarf planet Pluto brings Pluto inside Neptune’s orbit for a 20-year period out of every 248 Earth years. Pluto can never crash into Neptune, though, because for every three laps Neptune takes around the Sun, Pluto makes two. This repeating pattern prevents close approaches of the two bodies.

Nearly 4.5 billion kilometers (2.8 billion miles) from the Sun, Neptune orbits the Sun once every 165 years. 

Uranus’ blue-green color is also the result of atmospheric methane, but Neptune is a more vivid, brighter blue, so there must be an unknown component that causes the more intense color. 

Despite its great distance and low energy input from the Sun, Neptune’s winds can be three times stronger than Jupiter’s and nine times stronger than Earth’s.

Winds on Neptune travel faster than the speed of sound.

In 1989, Voyager 2 tracked a large, oval-shaped, dark storm in Neptune’s southern hemisphere. This “Great Dark Spot” was large enough to contain the entire Earth.

Neptune has five known rings. Voyager 2’s observations confirmed that these unusual rings are not uniform but have four thick regions (clumps of dust) called arcs. The rings are thought to be relatively young and short-lived.

Neptune has 14 known moons, six of which were discovered by Voyager 2.

Triton, Neptune’s largest moon, orbits the planet in the opposite direction compared with the rest of the moons, suggesting that it may have been captured by Neptune in the distant past. 

To know more about the planet Neptune click here and here.

Images credit: NASA/JPL- Caltech (some images processed by Kevin M. Gill)

Three Ways to Travel at (Nearly) the Speed of Light

One hundred years ago, Einstein’s theory of general relativity was supported by the results of a solar eclipse experiment. Even before that, Einstein had developed the theory of special relativity — a way of understanding how light travels through space.

Particles of light — photons — travel through a vacuum at a constant pace of more than 670 million miles per hour.

All across space, from black holes to our near-Earth environment, particles are being accelerated to incredible speeds — some even reaching 99.9% the speed of light! By studying these super fast particles, we can learn more about our galactic neighborhood. 

Here are three ways particles can accelerate:

1) Electromagnetic Fields!

Electromagnetic fields are the same forces that keep magnets on your fridge! The two components — electric and magnetic fields — work together to whisk particles at super fast speeds throughout the universe. In the right conditions, electromagnetic fields can accelerate particles at near-light-speed.

We can harness electric fields to accelerate particles to similar speeds on Earth! Particle accelerators, like the Large Hadron Collider and Fermilab, use pulsed electromagnetic fields to smash together particles and produce collisions with immense amounts of energy. These experiments help scientists understand the Big Bang and how it shaped the universe!

2) Magnetic Explosions!

Magnetic fields are everywhere in space, encircling Earth and spanning the solar system. When these magnetic fields run into each other, they can become tangled. When the tension between the crossed lines becomes too great, the lines explosively snap and realign in a process known as magnetic reconnection. Scientists suspect this is one way that particles — for example, the solar wind, which is the constant stream of charged particles from the Sun — are sped up to super fast speeds.

When magnetic reconnection occurs on the side of Earth facing away from the Sun, the particles can be hurled into Earth’s upper atmosphere where they spark the auroras.

3) Wave-Particle Interactions!

Particles can be accelerated by interactions with electromagnetic waves, called wave-particle interactions. When electromagnetic waves collide, their fields can become compressed. Charged particles bounce back and forth between the waves, like a ball bouncing between two merging walls. These types of interactions are constantly occurring in near-Earth space and are responsible for damaging electronics on spacecraft and satellites in space.

Wave-particle interactions might also be responsible for accelerating some cosmic rays from outside our solar system. After a supernova explosion, a hot, dense shell of compressed gas called a blast wave is ejected away from the stellar core. Wave-particle interactions in these bubbles can launch high-energy cosmic rays at 99.6% the speed of light.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com. 

Swirls of Jupiter

Jupiter is a very stormy, turbulent, violent planet. The planet completes a day (or one complete rotation) within roughly 10 hours, which creates massive winds, producing these swirls, and violent storms. The fast rotation coupled with the fact that the planet is nothing but gas greatly multiplies the Coriolis effect. Earth too has a Coriolis effect, this creates the characteristic hurricane shapes and also contributes to the fact that storms will spin the opposite direction in different hemispheres. Luckily, our rotation is slower - our storms are less frequent and less violent than they would be if our days were shorter.

The above images come from the recent Juno mission by NASA.

Blanet: A new class of planet that could form around black holes

The dust clouds around supermassive black holes are the perfect breeding ground for an exotic new type of planet.

Blanets are fundamentally similar to planets; they have enough mass to be rounded by their own gravity, but are not massive enough to start thermonuclear fusion, just like planets that orbit stars. In 2019, a team of astronomers and exoplanetologists showed that there is a safe zone around a supermassive black hole that could harbor thousands of blanets in orbit around it.

The generally agreed theory of planet formation is that it occurs in the protoplanetary disk of gas and dust around young stars. When dust particles collide, they stick together to form larger clumps that sweep up more dust as they orbit the star. Eventually, these clumps grow large enough to become planets.

A similar process should occur around supermassive black holes. These are surrounded by huge clouds of dust and gas that bear some similarities to the protoplanetary disks around young stars. As the cloud orbits the black hole, dust particles should collide and stick together forming larger clumps that eventually become blanets.

The scale of this process is vast compared to conventional planet formation. Supermassive black holes are huge, at least a hundred thousand times the mass of our Sun. But ice particles can only form where it is cool enough for volatile compounds to condense.

This turns out to be around 100 trillion kilometers from the black hole itself, in an orbit that takes about a million years to complete. Birthdays on blanets would be few and far between!

An important limitation is the relative velocity of the dust particles in the cloud. Slow moving particles can collide and stick together, but fast-moving ones would constantly break apart in high-speed collisions. Wada and co calculated that this critical velocity must be less than about 80 meters per second.

source

All Cats Are Beautiful

The Shrinking Aral Sea

The Aral Sea was once the fourth-largest lake in the world. Fed primarily by snowmelt and precipitation flowing down from faraway mountains, it was a temperate oasis in an arid region. But in the 1960s, the Soviet Union diverted two major rivers to irrigate farmland, cutting off the inland sea from its source. As the Aral Sea dried up, fisheries collapsed, as did the communities that depended on them. The remaining water supply became increasingly salty and polluted with runoff from agricultural plots. Loss of the Aral Sea’s water influenced regional climate, making the winters even colder and the summers much hotter.

While seasonal rains still bring water to the Aral Sea, the lake is roughly one-tenth of its original size. These satellite images show how the Aral Sea and its surrounding landscape has changed over the past few decades.

For more details about these images, read the full stories here: https://go.nasa.gov/2PqJ1ot

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

Earth: Our Oasis in Space

Earth: It’s our oasis in space, the one place we know that harbors life. That makes it a weird place – so far, we haven’t found life anywhere else in the solar system…or beyond. We study our home planet and its delicate balance of water, atmosphere and comfortable temperatures from space, the air, the ocean and the ground.

To celebrate our home, we want to see what you love about our planet. Share a picture, or several, of Earth with #PictureEarth on social media. In return, we’ll share some of our best views of our home, like this one taken from a million miles away by the Earth Polychromatic Imaging Camera (yes, it’s EPIC).

From a DC-8 research plane flying just 1500 feet above Antarctic sea ice, we saw a massive iceberg newly calved off Pine Island Glacier. This is one in a series of large icebergs Pine Island has lost in the last few years – the glacier is one of the fastest melting in Antarctica.

It’s not just planes. We also saw the giant iceberg, known as B-46, from space. Landsat 8 tracked B-46’s progress after it broke off from Pine Island Glacier and began the journey northward, where it began to break apart and melt into the ocean.

Speaking of change, we’ve been launching Earth-observing satellites since 1958. In that time, we’ve seen some major changes. Cutting through soft, sandy soil on its journey to the Bay of Bengal, the Padma River in Bangladesh dances across the landscape in this time-lapse of 30 years’ worth of Landsat images.  

Our space-based view of Earth helps us track other natural activities, too. With both a daytime and nighttime view, the Aqua satellite and the Suomi NPP satellite helped us see where wildfires were burning in California, while also tracking burn scars and smoke plumes..

Astronauts have an out-of-this-world view of Earth, literally. A camera mounted on the International Space Station captured this image of Hurricane Florence after it intensified to Category 4.

It’s not just missions studying Earth that capture views of our home planet. Parker Solar Probe turned back and looked at our home planet while en route to the Sun. Earth is the bright, round object.

Want to learn more about our home planet? Check out our third episode of NASA Science Live where we talked about Earth and what makes it so weird. 

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com