Cassini // Mac Rebisz
Space Station Systems | NASA | 1988
NASA’s Hubble Space
Telescope captured this stunning image of comet C/2019 Y4 (ATLAS)
breaking apart on 20 April 2020. The comet was discovered in December
2019 and brightened through March 2020, leading astronomers to guess it
might become visible to the naked eye as it passed about 116 million
kilometers (72 million miles) from Earth in May. Unfortunately, the
comet’s icy core fragmented, all but ending hopes for a good show in the
night sky.
A large asteroid is due to pass on April 29
A big – very big – asteroid will pass relatively close to Earth on April
29, 2020. Asteroid (52768) 1998 OR2 will pass at a safe distance, at
some 4 million miles (6 million km), or about 16 times the Earth-moon
distance. It’ll be the biggest asteroid to fly by Earth this year (that
we know about so far); according to current estimates, it’s probably a
bit over a mile wide (2 km) and maybe twice that long. Closest approach
will be April 29 around 5:56 a.m. Eastern Daylight Time (09:56 UTC; translate UTC to your time).
Professional observatories have been pointing their telescopes at the
huge space rock already. Amateur astronomers with smaller telescopes
will also have an opportunity to see it as a slow-moving “star.” If
that’s you, we give charts and tips for observers at the bottom of this post that should help.
In
this photo released Wednesday, April 22, 2020, by Sepahnews, an Iranian
rocket carrying a satellite is launched from an undisclosed site
believed to be in Iran’s Semnan province. Iran’s Revolutionary Guard
said Wednesday it put the Islamic Republic’s first military satellite
into orbit, dramatically unveiling what experts described as a secret
space program with a surprise launch that came amid wider tensions with
the United States. (Sepahnews via AP)
Do We Live in a Lopsided Universe?
According to the key tenets of modern physics, the cosmos is “isotropic” at multi-billion-light-year scales—meaning it should have the same look and behavior in every direction. Ever since the big bang nearly 14 billion years ago, the universe ought to have expanded identically everywhere. And that expectation matches what astronomers see when they observe the smooth uniformity of the big bang’s all-sky afterglow: the cosmic microwave background (CMB). Now, however, an x-ray survey of distances to galaxy clusters across the heavens suggests some are significantly closer or farther away than isotropy would predict. This finding could be a sign that the universe is actually “anisotropic”—expanding faster in some regions than it does in others. With apologies to anyone seeking a cosmic excuse for personal woes, maybe the universe is not so directionless after all.
This possible evidence for anisotropy comes from an international team led by astronomer Konstantinos Migkas of the University of Bonn in Germany. And it relies on new or archival data on nearly 850 galaxy clusters seen by NASA’s Chandra X-ray Observatory, the European Space Agency’s XMM-Newton satellite and Japan’s Advanced Satellite for Cosmology and Astrophysics.
Exoplanet Apparently Disappears in Latest Hubble Observations
What astronomers thought was a planet beyond our solar system has now seemingly vanished from sight. Though this happens in science fiction, such as Superman’s home planet Krypton exploding, astronomers are looking for a plausible explanation.
One interpretation is that, rather than being a full-sized planetary object, which was first photographed in 2004, it could instead be a vast, expanding cloud of dust produced in a collision between two large bodies orbiting the bright nearby star Fomalhaut. Potential follow-up observations might confirm this extraordinary conclusion.
“These collisions are exceedingly rare and so this is a big deal that we actually get to see one,” said András Gáspár of the University of Arizona, Tucson. “We believe that we were at the right place at the right time to have witnessed such an unlikely event with NASA’s Hubble Space Telescope.”
Interstellar Comet Borisov Reveals Its Chemistry and Possible Origins
On Aug. 30, 2019, when amateur astronomer Gennady Borisov gazed upward with his homemade telescope, he spotted an object moving in an unusual direction. Now called 2I/Borisov, this runaway point of light turned out to be the first confirmed comet to enter our solar system from some unknown place beyond our Sun’s influence. Astronomers everywhere rushed to take a look with some of the most powerful instruments in the world, hoping to learn as much as they could about the mysterious visitor.
Now, thanks to observations with NASA’s Hubble Space Telescope and the National Radio Astronomy Observatory’s Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have figured out that 2I/Borisov has an unusual composition. Specifically, it has a higher concentration of carbon monoxide than any comet seen at a similar distance; that is, within about 200 million miles (300 million kilometers) of the Sun.
This suggests to scientists that the comet could have formed around a red dwarf — a smaller, fainter type of star than the Sun — though other kinds of stars are possible. Another idea is that 2I/Borisov could be a carbon monoxide-rich fragment of a small planet.
The New Horizons Parallax Program
Since its launch in January 2006, NASA’s New Horizons spacecraft has flown past Jupiter in 2007, Pluto in 2015, and most recently, the Kuiper Belt object Arrokoth in 2019. Speeding through the Kuiper Belt at some 31,000 miles (50,000 kilometers) per hour, it’s on a fast path out of the solar system and toward the Milky Way galaxy.
This spring, New Horizons will be more than 46 times farther from the Sun than the Earth, having traveled more than 5 billion miles (8 billion kilometers) since launch. At this great distance, from New Horizons’ view, the nearest stars will appear to have shifted in position relative to more distant stars, compared to where we see them from Earth. On April 22 and 23, 2020, New Horizons will gather images of two of the nearest stars, Proxima Centauri and Wolf 359, to demonstrate this effect.
Earth-Size, Habitable Zone Planet Found Hidden in Early NASA Kepler Data
A team of transatlantic scientists, using reanalyzed data from NASA’s Kepler space telescope, has discovered an Earth-size exoplanet orbiting in its star’s habitable zone, the area around a star where a rocky planet could support liquid water.
Scientists discovered this planet, called Kepler-1649c, when looking through old observations from Kepler, which the agency retired in 2018. While previous searches with a computer algorithm misidentified it, researchers reviewing Kepler data took a second look at the signature and recognized it as a planet. Out of all the exoplanets found by Kepler, this distant world – located 300 light-years from Earth – is most similar to Earth in size and estimated temperature.
New formation theory explains the mysterious interstellar object ‘Oumuamua
First author Yun Zhang at the National Astronomical Observatories of the Chinese Academy of Sciences and coauthor Douglas N. C. Lin at UC Santa Cruz, used computer simulations to show how objects like ‘Oumuamua can form under the influence of tidal forces like those felt by Earth’s oceans. Their formation theory explains all of ‘Oumuamua’s unusual characteristics.
“We showed that ‘Oumuamua-like interstellar objects can be produced through extensive tidal fragmentation during close encounters of their parent bodies with their host stars, and then ejected into interstellar space,” said Lin, professor emeritus of astronomy and astrophysics at UC Santa Cruz.
The joint European-Japanese Mercury spacecraft BepiColombo took a series
of final glimpses of Earth on 10 and 11 April 2020, as it moved away
from our planet after the gravity-assist flyby
performed in the early hours of 10 April. The images, showing Earth as a
receding crescent against the darkness of space, were captured by one
of the MCAM selfie cameras mounted on the Mercury Transfer Module (MTM), one of the three components of the BepiColombo mission.
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