Midmonth Check-In: December 2020

     I hope this mid month check-in post finds all of you doing well, staying safe, and keeping warm!  Within the past month or so, there have been a couple more asteroids that came close to Earth and a few fireballs seen above various countries due to larger meteors burning up in the atmosphere.  There have also been two rocket launches to the ISS, one carrying new crew and the other carrying supplies for those staying on the ISS.  I was also able to watch the launch of Sentinel-6 on NASA TV whose purpose is to monitor global sea levels.  Construction has also begun on the new Space Launch System (SLS) rocket at NASA which is designed to take humans back to the Moon and potentially to Mars.  

    There will be some exciting events from NASA taking place in 2021 with the latest Mars mission due to arrive at the red planet in February.  Later in the year, there is also the chance of the James Webb Space Telescope (JWST) being launched.  This mission has been pushed back several times due to budget cuts and other missions taking precedence over it.  The Hubble Space Telescope (HST) consists of one mirror that is slightly taller than an average human.  The HST primarily looks at objects in the visual and UV range of the electromagnetic spectrum.  The JWST will consist of 18 mirrors which are approximately the same size as the single mirror in the HST!  This telescope will be able to see even more detail than HST due to its much larger size.  It will primarily study objects using the visual and the infrared end of the spectrum.  The JWST will be placed at about 1.5 million kilometers (approximately 930,000 miles) from the Earth in a location known as L2 or Lagrange Point 2.  This is an area in space where the gravity of the Earth and Sun cancel each other out so the telescope can "float" in place with minimal adjustments to its orbit.  Hubble is a mere 570 kilometers (approximately 350 miles) above the surface of the Earth.  

    While on the topic of telescopes, many of you may have likely heard about the failure of the main telescope at the Arecibo Observatory in Puerto Rico.  Due to hurricanes and a limited budget, the main telescope was destroyed, which was the largest telescope of its kind.  You may be familiar with a reflecting telescope, like mine pictured below, which uses a large mirror (primary mirror) to collect light, and a smaller mirror (secondary mirror) to direct the light to your eyepiece.  In my telescope, the primary mirror is located at the bottom of the telescope (near the red chair on the right) while the secondary mirror is located just behind the focuser (protruding part near the top on the otherwise smooth "cannon"), near the top of the telescope.    

My telescope, as well as most other amateur telescopes, allows the user to see objects in the visible part of the EM spectrum.  Instead of collecting visible light, the Arecibo telescope collects radio waves into a large dish consisting of nearly 40,000 panels made of aluminum.  These panels then reflect the radio waves to a single point which focuses them before they are analyzed by computers.  Just as creating a larger mirror will collect more light and be able to show fainter objects in the visual range, a large radio telescope can collect fainter radio signals to be analyzed.  Unlike optical telescopes, several radio telescopes can be built and set up in arrays to act as a single large telescope instead of many smaller instruments.  

    Objects in the universe emit many different wavelengths of light.  These include the visible range which humans are most familiar with as well as several others which you have likely heard of, such as infrared, microwaves, X-rays, and ultraviolet rays.  The visible range makes up a tiny part of the spectrum of light waves.  Radio waves also make up a small section of the EM spectrum, which radio telescopes are able to pick up.  These are the same type of waves that radio antennas pick up so that you can listen to the radio in your car or home.  Radio waves in the universe can be emitted by stars, galaxies, and black holes, among other things.  Arecibo was used to detect these faint waves and was also used by SETI to potentially detect radio waves from other civilizations.  Below is an image of Arecibo taken by the National Science Foundation before it was damaged.

The radio waves would be collected by the large dish and focused to a single point above the center of the dish which is just below the scaffolding in the image.  Once the data is focused, it is sent to a computer where the data can be analyzed.  The cables that can be seen connecting the three towers to the central scaffolding failed, causing the central area to collapse onto the dish below.  As of this post, there are no plans to reconstruct this telescope but hopefully some group will take interest and be able to make Arecibo operational once again.

The following image is of the Very Large Array Observatory in New Mexico.  This image was also taken by the NSF and was featured on the Astronomy Picture of the Day.  As you can see, this observatory is made up of many smaller radio telescopes which when used together, act as a much larger telescope.  Optical telescopes are best used away from interfering light caused by city lights and other nearby light sources.  Similarly, radio telescopes work best when they are far away from radio wave sources such as cities, cell phone towers, and the like.  

Currently, the world's largest and fully steerable radio telescope is located at Green Bank Observatory in West Virginia.  Since this telescope is steerable, it is able to be aimed at any part of the sky to detect radio waves.  The dish of this telescope measures about 300 feet, which is larger than a football field!  This telescope is so sensitive that no radio signals of any kind are allowed within 50 miles of it.  This includes cordless phones, cell phones, wi-fi and even gas-powered cars!  Visiting this area is like stepping back into the 1950's.  Below is an image of the Green Bank Telescope taken by the NSF.  

    We have just passed the peak date of the Geminid Meteor Shower.  If you were unable to view them on that date, you should still be able to see quite a few meteors as the Earth continues to plow through the ice and dust that contributes to this shower.  

Over the past few weeks, I have been watching Jupiter and Saturn moving closer together.  The great conjunction between these planets is just around the corner!  This will occur on the 21st and will feature both Jupiter and Saturn in a single field of view with a pair of binoculars or by using an eyepiece with a wide field of view in a telescope.  This conjunction can be viewed as soon as you are able to see Jupiter with the unaided eye.  Be sure to dress warmly!  The winter solstice will occur on the same day as the conjunction, meaning that we will now have more daylight in the northern hemisphere as the tilt of the Earth's axis slowly wobbles towards the Sun.  

As we begin a new year, you can again look at the wonders of the night sky, such as star clusters, nebulae, and galaxies, that you viewed in 2020 or perhaps you will find a new favorite object.  Stay warm and stay safe for the remainder of the year and don't forget to get outside and look up!           

Now get outside and look up!