“We finally have the first look at our Milky Way black hole, Sagittarius A*,”an international team of astrophysicists(天文物理学家)and researchers from the Event Horizon Telescope team announced     1    (proud)on Thursday.

For years, the supermassive black hole in the dark center of the Milky Way galaxy     2    (study)——and eventually, it’s been captured(捕捉)in an image. The black hole is often referred to     3     Sgr A*. Its mass is about 4 million times     4     of the sun, and it’s about 27,000 light years from Earth.

What made capturing the image extra     5    (challenge)was the dynamic enyironment of Sgr A*, and the challenges of looking not only through the earth’s atmosphere     6     also through the gas clouds in the disk of the Milky Way galaxy towards the center. It took several years to refine the images.

“Although we cannot see the black hole     7    (it), because it is completely dark, glowing(发光的)gas around it reveals a telltale signature, a dark central region    8    (surround)by a bright ring-like structure,” the Event Horizon Telescope team said in its announcement.

The     9    (discover)comes three years after the Event Horizon Telescope Collaboration released the first-ever image of a black hole—but that work focused on     10     center of galaxy Messier 87, tens of millions of light-years away from Earth in the Virgo cluster of galaxies.

The Perseverance Rover on Mars continues to perform amazing feats of science. Most recently, an instrument on the Perseverance     1     (turn) carbon dioxide into oxygen, a process that could one day help astronauts breathe on the red planet.

96%of the Martian atmosphere is carbon dioxide, which doesn’t do much for humans who need oxygen     2     (breathe). Scientists say it is a critical first step in     3     (change) carbon dioxide into oxygen on Mars. The experimental instrument aboard Perseverance     4     (know)as MOXIE.

“MOXIE has more work to do. It is helping us move toward our goal of one day seeing humans on Mars, ”scientists say. “Oxygen serves a much     5     (great) purpose than just being the air we breathe. The rocket propellant (推进剂) depends     6     (heavy) on oxygen,     7     future explorers will depend on producing propellants on Mars to make the trip home. Whether for rockets     8     astronauts, oxygen is the key. ”

MOXIE works     9     separating oxygen atoms from carbon dioxide molecules, which are made up of one carbon atom and two oxygen atoms. A waste product, carbon monoxide, is emitted into the Martian atmosphere. Much larger and better     10     (version) of MOXIE could be used to turn huge quantities of carbon dioxide into oxygen.

Using a three-dimensional (3-D) transmission electron microscopy technique, a group of Chinese scientists have discovered a new phenomenon in the deformation (变形) of nanometals, which will help improve material design and engineering applications.

Huang Xiaoxu, a world-renowned scientist in the field of materials science,     1     (lead) a team at the College of Materials Science and Engineering of Chongqing University and its cooperators, created the world’s first 3-D microscopy technique system     2     tracked the rotations of individual grains in a nanograined nickel before and after in situ nanomechanical testing. The testing enables the observation of how the materials respond to applied stress in     3     (they) native state, which is fundamental to understand their mechanical     4     (property), said the research.

They found that the nanosized grains sometimes experience lattice rotations different from the     5     (theory) prediction. This unexpected lattice rotation occurs more often in the larger grains and is due to a phenomenon     6     (call) back stress, which generates the rotation.

Huang Xiaoxu’s team     7     (develop) 3-D microscopy techniques over the past 10 years. The microscopy is equipped     8     self-developed controlling hardware and software to enhance the efficiency of image collection and processing.

“In the past, with conventional microscopy, scientists could only observe the material deformation in a two-dimensional way,     9     often led to incomplete or even misleading results,” said Huang. “Now we can     10     (eventual) observe the deformation in 3-D, and our first finding using the technique.”