There are billions of billions of galaxies in the known universe. They are oriented in countless different ways. A small fraction show their full face toward Earth, while some show an edge-on view. This first example is a nearly face-on view of NGC 4414. Imaged by the Hubble Telescope in 1995, it lies about 60 million lt-yr from Earth. Only about half of the galaxy fit into the detector of Hubble due to its large size.
Three red, green, and blue filtered greyscale images were used to make my color version of this galaxy. The center region is densely populated with older yellow and red stars. This is typical of spiral galaxies. The outer regions are less populated and include younger blue stars. The galaxy has a lot of dust mixed into the spiral arms as evidenced by the dark clouds and bands in silhouette against the bright star glow.
This next galaxy is a nearly perfect edge-on view of NGC 4013. The very bright light source at the heart of this galaxy is actually a star in the foreground much closer than the galaxy. It is part of our Milky Way galaxy and just happens to be in alignment. NGC 4013 is about 55 million lt-yr away in the direction of Ursa Major, the Big Dipper. If we could see it face-on, it would have a spiral shape similar to NGC 4414 above. What stands out clearly in this edge-on view is the dark band of dust cutting across the width of the galaxy. A few blue stars show in the upper right. They are in an outer band and less obscured by the dust.
In April 2019, astronomers with the Event Horizon Telescope EHT released the most detailed image of the region near a black hole in the large elliptical galaxy M87. This image was the first view inside the core of a galaxy showing the extremely energetic spinning disc, or donut, of material and radiation surrounding the invisible black hole at the center. Material falling into the black hole disappears within this horizon. Not even light can escape. This black hole is about 55 million light-years from us and has a mass 6.5 million times that of our Sun.
We are not seeing the black hole. We are aware of the absence of anything visible in the center. That is where the black hole is located. I invite you to read my previous non-technical post about this story.
In April 2021, new findings from multiple radio, optical, X-ray, and gamma-ray telescopes were shared revealing greater detail about the broader surroundings and processes taking place in the vicinity of galaxy M87. The telescopes are ground based and some are space based. They observed in wavelengths from long radio waves of many meters, the more familiar shorter waves of the optical spectrum, and in extremely short X-ray and gamma-ray wavelengths. Such broad coverage will give scientists greater insights into the dynamics near black holes and aid their understanding of Einstein’s General Theory of Relativity.
Much of the excitement has settled now that Mars 2020 Perseverance Rover is safely on the surface of Mars after the 18 Feb 2021 landing. I gathered images and links to a collection of things I feel tell the story of this rover in a not too complicated way. The mission is very challenging. A primary goal is to find evidence that microbial life may have existed on the Martian surface in the past.
You might wonder where Perseverance landed and why is that place is important. Landing took place in Jezero Crater. The crater is about 49 km (30 mi) across. It is believed to have once been filled with water. This image shows a dried riverbed and delta of a water source that once flowed left-to-right and filled the crater. The colors are indicators of various types of mineral deposits and not actual colors. The rover landed in the lower right quadrant of this image just below the two side-by-side small craters on the flat plain and not far from the delta formation.
Ancient river delta into Jezero Crater | MRO | NASA
Scientists and space enthusiasts are excited about the upcoming landing of the exploration rover Perseverance on the surface of Mars on 18 Feb 2021. The NASA-TV broadcast from Mission Control starts at 11:15 am PST/2:15 pm EST.
The mission is designed to look for bio-signatures in a river delta of an ancient lakebed. It will harvest rock-core samples for analysis and possible return to Earth in a future mission. The rover will be joined by a small helicopter to extend its vision and reach around the area. This video (< 3 min) shows the basics of the rover design and plans for the mission. You are invited to explore more about the mission at this link.
Perseverance helicopter being examined by NASA engineers
Perseverance was launched in July of 2020. It took 7 months to coast to this meeting with Mars. On a collision course, it will enter the thin atmosphere at over 12,000 mph. The challenge is how to safely slow the vehicle and land it. This following graphic illustrates the overall plan, but not to scale.
The fast-moving craft in coast phase enters the atmosphere at upper left. A heat shield protects it and slows it down from 12,000 to 950 mph. A parachute deploys and the heat shield falls away. The craft scans the terrain to find the landing site.
At 180 mph and 1.3 miles altitude, the parachute is detached letting the vehicle fall. Rocket engines control the descent and slow it down to less than 2 mph and 60 ft. above the surface. The rover is lowered about 20 ft more by cables to touchdown on the surface. The cables detach and the rocket assembly flies far out of the way.
Lowering of rover by cables for touchdown | NASA
The technique has been done before in 2012 when the Curiosity rover landed on Mars. It was described then as 7 minutes of terror. Mars is far from Earth. By the time radio signals reach us more than 11 minutes later, events will already have played out, successfully or not. All actions are programmed. Curiosity is still functioning well on Mars today. Here is a recent selfie.
What will the Moon look like on any date in 2021? What will it look like on your birthday? Find out at NASA Dial-a-Moon. The example pictured below is for 16 January 2021. Set dates and see views for northern hemisphere and for southern hemisphere readers by following either link. Enter any month and day to see a high definition image. You may leave the universal time (UT) at the default value. If you wish, your local-to-Universal time conversion can be done at this link. Or, type ‘universal time’ into Google. Go back to Dial-a-Moon to enter the UT.
After visiting Dial-a-Moon, scan down that web page for a wealth of additional information about the Moon’s motions and appearance. The images of Dial-a-Moon are made from those of the Lunar Reconnaissance Orbiter (LRO) in low altitude orbit around the Moon since 2009.