Archive for the ‘Astronomy’ Category

Lagrange points in the Sun–Earth system (not to scale). A small object at L4 or L5 will hold its relative position [Credit: Xander89 @ Wikipedia]


More about Lagrange points here.
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A recently discovered asteroid appears to be an Earth Trojan, orbiting a gravitationally stable area with only one other known occupant, says Sky & Telescope.

Trojans are asteroids gravitationally locked to stable Lagrange points either 60° ahead (L4) or behind (L5) the planets in their orbits around the Sun. 2020 XL5 was found around the L4 point.

Massive Jupiter has more than 9,000 Trojans.

In theory, Trojan orbits would be stable around every planet except Saturn, where Jupiter’s gravity pulls them away.

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NASA’s exoplanet hunter (TESS)
[image credit: MIT]


This three-planet system has orbit periods ranging from under two to over sixteen days, obviously another very compact group. Their star is slightly smaller and less powerful than our Sun.

Planets b and c are a fraction of Jupiter’s size, but planet d is vast with a radius of over four Jupiters, or about 45 Earth radii.

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Credit: NASA


This six-planet system has orbit periods from 1.9~ to 20.7~ days, all much closer to their star than Mercury is to the Sun.

It was recently ‘upgraded’ from the three planets discovered in 2018 and 2019.

As usual, the key to understanding the timings of the orbits is to look at the conjunction periods of the neighbour pairs.

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Credit: wcia.com


How to see it, plus videos – here.
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Jupiter and Saturn will merge in the night sky Monday, appearing closer to one another than they have since Galileo’s time in the 17th century, says Phys.org.

Astronomers say so-called conjunctions between the two largest planets in our solar system aren’t particularly rare.

Jupiter passes its neighbor Saturn in their respective laps around the sun every 20 years.

But the one coming up is especially close: Jupiter and Saturn will be just one-tenth of a degree apart from our perspective or about one-fifth the width of a full moon.

They should be easily visible around the world a little after sunset, weather permitting.

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Bright Comet Erasmus

Posted: November 22, 2020 by oldbrew in Astronomy, News, solar system dynamics

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Short video here.

Spaceweather.com

Nov. 21, 2020: Every 2000 years, Comet Erasmus (C/2020 S3) visits the inner Solar System. News Flash: It’s back. Discovered on Sept. 17, 2020, by South African astronomer Nicolas Erasmus, the dirty snowball is plunging toward the sun for a close encounter inside the orbit of Mercury on Dec. 12th. This is what it looks like:

Gerald Rhemann took the picture Friday morning, Nov. 20th, using a 12-inch telescope in Farm Tivoli, Namibia. “The tail is magnificent,” he says. “In fact, I couldn’t fit it in a single field of view. This two-panel composite shows the first 3 degrees–and it keeps going well past the edge of the photo.”

Comet Erasmus is brightening as it approaches the sun. Right now it is 7th magnitude–an easy target for backyard telescopes. Forecasters believe it will more than triple in brightness to 5th magnitude by the time it dips inside the orbit of Mercury…

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Super-WASP telescope site, La Palma [image credit: lapalma-island.com]


In nearly six years there are 247 b and 63 c orbits. Since 248:62 is 4:1, it can be seen why the observed ‘acceleration and deceleration’ of the planets might occur.
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Astronomers using the SuperWASP-North telescope on La Palma in the Canary Islands, Spain, and the SOPHIE spectrograph at the Observatoire de Haute-Provence, France, have discovered two giant exoplanets circling the G-type dwarf star WASP-148, reports Science News.

WASP-148 is a slowly rotating, inactive G-dwarf star 809 light-years away in the constellation of Hercules.

Also known as TYC 3083-295-1 and 2MASS J16563135+4418095, the star has the same mass and radius as the Sun.

WASP-148 hosts a planetary system composed of at least two giant planets, WASP-148b and c.

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Credit: NASA


Could there even be more than one black hole? The search for a significant extra planet has drawn a blank so far.
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A coming sky survey will help test a wild idea — that a grapefruit-sized black hole lurks undiscovered in the outer solar system, says Mike Wall @ Space.com.

Over the past few years, researchers have noticed an odd clustering in the orbits of multiple trans-Neptunian objects (TNOs), which dwell in the dark depths of the far outer solar system.

Some scientists have hypothesized that the TNOs’ paths have been sculpted by the gravitational pull of a big object way out there, something 5 to 10 times more massive than Earth (though others think the TNOs may just be tugging on each other).

This big “perturber,” if it exists, may be a planet — the so-called “Planet Nine,” or “Planet X” or “Planet Next” for those who will always regard Pluto as the ninth planet.

But there’s another possibility as well: The shepherding object may be a black hole, one that crams all that mass into a sphere the size of a grapefruit.

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Their orbits have a ratio of 247:63, whereas 248:62 = 4:1.
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Several interacting exoplanets have already been spotted by satellites.

But a new breakthrough has been achieved with, for the first time, the detection directly from the ground of an extrasolar system of this type, reports Phys.org.

An international collaboration including CNRS researchers has discovered an unusual planetary system, dubbed WASP-148, using the French instrument SOPHIE at the Observatoire de Haute-Provence (CNRS/Aix-Marseille Université).

The scientists analyzed the star’s motion and concluded that it hosted two planets, WASP-148b and WASP-148c. The observations showed that the two planets were strongly interacting, which was confirmed from other data.

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Nabta Playa


An inventory of Egyptian archaeo-astronomical sites for the UNESCO World Heritage Convention evaluated Nabta Playa as having “hypothetical solar and stellar alignments.” – Wikipedia.
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This 7,000-year-old stone circle tracked the summer solstice and the arrival of the annual monsoon season. It’s the oldest known astronomical site on Earth, says Discover magazine.

For thousands of years, ancient societies all around the world erected massive stone circles, aligning them with the sun and stars to mark the seasons.

These early calendars foretold the coming of spring, summer, fall and winter, helping civilizations track when to plant and harvest crops.

They also served as ceremonial sites, both for celebration and sacrifice.

These megaliths — large, prehistoric monuments made of stone — may seem mysterious in our modern era, when many people lack a connection with, or even view of, the stars.

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During a total solar eclipse, the Sun’s corona and prominences are visible to the naked eye [image credit: Luc Viatour / https://Lucnix.be ]


There’s an interesting time-series animation of the solar corona here. Clear differences in the corona at solar minimum compared to maximum were observed by the globetrotting researchers.
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While the world has been dealing with the coronavirus pandemic, researchers at the University of Hawaiʻi Institute for Astronomy (IfA) have been hard at work studying the solar corona, the outermost atmosphere of the sun which expands into interplanetary space, reports Phys.org.

This stream of charged particles radiating from the surface of the sun is called the solar wind and expands to fill the entire solar system.

The properties of the solar corona are a consequence of the sun’s complex magnetic field, which is produced in the solar interior and extends outward.

A new study by IfA graduate student Benjamin Boe, published Wednesday, June 3rd in the Astrophysical Journal, used total solar eclipse observations to measure the shape of the coronal magnetic field with higher spatial resolution and over a larger area than ever before.

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Credit: NASA


Looks like game over for the Planet Nine idea. Unavoidable observational biases may be at least partly to blame.
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Planet Nine is a theoretical, undiscovered giant planet in the mysterious far reaches of our solar system, says The Conversation (via Phys.org)

The presence of Planet Nine has been hypothesized to explain everything from the tilt of the sun’s spin axis to the apparent clustering in the orbits of small, icy asteroids beyond Neptune.

But does Planet Nine actually exist?

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Browsing twitter recently I ran across this short video of a solar flare shot a few days ago.

After asking for some clarification on frame rate I was really intrigued.

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The linked article contains more video material and images.
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In February 2020, NASA’s Solar Dynamics Observatory—SDO—is celebrating its 10th year in space, reports Phys.org.

Over the past decade the spacecraft has kept a constant eye on the sun, studying how the sun creates solar activity and drives space weather—the dynamic conditions in space that impact the entire solar system, including Earth.

Since its launch on Feb. 11, 2010, SDO has collected millions of scientific images of our nearest star, giving scientists new insights into its workings.

SDO’s measurements of the sun—from the interior to the atmosphere, magnetic field, and energy output—have greatly contributed to our understanding of our closest star.

SDO’s images have also become iconic—if you’ve ever seen a close up of activity on the sun, it was likely from an SDO image.

SDO’s long career in space has allowed it to witness nearly an entire solar cycle—the sun’s 11-year cycle of activity.

Here are a few highlights of SDO’s accomplishments over the years.

Visualization of the Radcliffe Wave. The wave is marked by red dots. The Sun is represented by a yellow dot to show our proximity to this huge structure. Courtesy of Alyssa Goodman/Harvard University


Scientists have previously reported evidence for a 26-million-year cycle of extinction on Earth, but the idea has remained controversial and unexplained. Now the discovery of the Radcliffe Wave may offer an explanation, but has anyone so far said so?

The team also found the wave interacts with the Sun. It crossed our path about 13 million years ago and will again in another 13 million years. What happened during this encounter is also unknown.

“There was no obvious mass extinction event 13 million years ago, so although we were crossing a sort of minefield back then, it did not leave an obvious mark,” Alves said. “Still, with the advent of more sensitive mass spectrometers, it is likely we will find some sort of mark left on the planet.”

13+13 = 26 (million). Can such a mark be found?
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From the article, ‘Something Appears to Have Collided with the Milky Way and Created a Huge Wave in the Galactic Plane’:

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Having one side of the planet constantly facing the star due to tidal locking could make habitability tricky though. There are three known planets in the system.
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From Wikipedia:
NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size planet in its star’s habitable zone, the range of distances where conditions may be just right to allow the presence of liquid water on the surface.

Scientists confirmed the find, called TOI 700 d, using NASA’s Spitzer Space Telescope and have modeled the planet’s potential environments to help inform future observations.

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The distance from the Oort cloud to the interior of the Solar System, and two of the nearest stars, is measured in astronomical units. The scale is logarithmic; each indicated distance is ten times farther out than the previous distance. The red arrow indicates the location of the space probe Voyager 1, which will reach the Oort cloud in about 300 years [credit: NASA / JPL-Caltech]


Note that the Oort Cloud referred to in the article, although often discussed as though it exists, has to date never been directly observed, perhaps due to its supposed great distance from Earth.
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Stars and comets make unlikely dance partners, says Live Science.

Their gravitational partnership is one that astronomers have long suspected but have never seen — until now. For the first time, a Polish group has identified two nearby stars that seem to have plucked up their icy partners, swinging them into orbits around our sun.

The astronomers found the stellar duo after studying the movements of over 600 stars that came within 13 light-years of the sun. The new findings validate a theory born more than a half-century ago, and in doing so have also shown just how rare these stellar dances can be.

Out on the far edge of the solar system, hanging like wallflowers around the planetary dance floor, is the Oort Cloud.

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Artist’s impression of the Kepler telescope [credit: Wikipedia]


So said researchers in their 2015 study which had that title. Then a third planet was seen.

In the abstract they say:

Methods. Our search through two separate pipelines led to the independent discovery of K2-19b and c, a two-planet system of Neptune-sized objects (4.2 and 7.2 R⊕), orbiting a K dwarf extremely close to the 3:2 mean motion resonance. The two planets each show transits, sometimes simultaneously owing to their proximity to resonance and the alignment of conjunctions.

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Credit: reference.com


There are many reasons NASA is pursuing the Artemis mission to land astronauts on the moon by 2024: It’s a crucial way to study the moon itself and to pave a safe path to Mars, says Phys.org.

But it’s also a great place to learn more about protecting Earth, which is just one part of the larger Sun-Earth system.

Heliophysicists—scientists who study the Sun and its influence on Earth—will also be sending up their own NASA missions as part of Artemis. Their goal is to better understand the complex space environment surrounding our planet, much of which is driven by our Sun.

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The predicted ninth planet has so far proved elusive, with searches of 50 per cent of the sky in the range where it ‘should’ be having turned up nothing. But planetary theorists Mike Brown and Konstantin Batygin insist the evidence shows they are on the right track. Others talk of broken glass and fingerprints – shades of Sherlock Holmes.

Beyond Neptune, a handful of small worlds are moving in harmony.

Astronomers think they might be dancing to the tune of a third world lurking in the darkness, one that’s four times bigger than Earth and significant enough to be named our Solar System’s ninth planet.

Now they think they know exactly where to look for it, says Science Focus.

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