Enjoy a bunch of awesome space facts and theories. Enjoy discussions about scifi and scifi-fantasy including such things as; space travel, wormholes, planet harvesting, space colonies, intergalactic communication, etc.
The comet Hale–Bopp (formally designated C/1995 O1) is a comet that was one of the most widely observed of the 20th century and one of the brightest seen for many decades.
Alan Hale and Thomas Bopp discovered Comet Hale–Bopp separately on July 23, 1995, before it became visible to the naked eye. It is difficult to predict the maximum brightness of new comets with any degree of certainty, but Hale–Bopp exceeded most predictions when it passed perihelion (the perihelion [q] and aphelion [Q] are the nearest and farthest points respectively of a body's direct orbit around the Sun) on April 1, 1997, reaching about magnitude −1.8. It was visible to the naked eye for a record 18 months, due to its massive nucleus size. This is twice as long as the Great Comet of 1811, the previous record holder. Accordingly, Hale–Bopp was dubbed the great comet of 1997.
Sadly, there was a tragic footnote to the appearance of Hale-Bopp, 39 people who were part of the "Heaven's Gate" cult in San Diego committed mass s*icide as the comet came close to Earth.
Interestingly enough, Hale-Bopp will return to view in roughly 2380 years as its orbit is incredibly wide and long.
Alloys and composites are both materials defined by the fact that they are composed of other materials. Alloys are metals, but they can be made of both metal and nonmetal elements, such as in the case of cast iron which is composed of iron (a metal) and carbon (a nonmetal). Composites, on the other hand, cannot be labeled as anything other than composites, but they too can be comprised of both metal and nonmetal elements such as reinforced concrete, which is made from cement (a nonmetal) and rebar (a metal, and actually an alloy itself). Both of these types of materials take advantage of the properties of their individual components, combining them in a way to produce a material with more favorable properties, be it strength, ductility, or electrical conductivity. How then, does one distinguish between an alloy and a composite that has a metal component?
To start with, alloys are thoroughly mixed together and their components can not readily be separated by physical means. In composites, however, the components are not blended and can be much more easily distinguished. Each material in a composite retains its properties, which is not the case for alloys. It is often said that alloys are homogeneous while composites are heterogeneous, though this is not quite true. While many alloys are homogeneous, they can also be heterogeneous, consisting of more than one phase, or intermetallic.
New Horizons: observations of Kuiper Belt object Quaoar, which - at 690 miles or 1,100 kilometers in diameter - is roughly half the size of Pluto (September 4, 2023)
Blazars produce light across the electromagnetic spectrum. Their powerful jets point almost directly at Earth, so they appear brighter than other active galaxies. Observatories on Earth can sometimes detect high-energy particles – like neutrinos – produced within the jets and trace them back to their home galaxy. This information gives scientists a glimpse into the environment around the blazar’s supermassive black hole.
Tar and asphalt are both dark, hard, sticky thermoplastic materials - becoming pliable upon heating but hardening again when cooled. They’re both used in construction (asphalt in roads more, tar more often in roofing), and they’re both complex mixtures of many, many chemical compounds, so it’s easy to understand why the two are so often confused.
The truth of the matter is, though, that aside from these commonalities, the two materials are vastly different all thanks to one thing: their origins. Whereas asphalt is derived from petroleum, which is said to originate from the decay of animal life over millions of years, tar is derived from coal, which is formed from the decay of vegetation over millions of years. Since plants and animals are vastly different organisms, comprised of different compounds and molecules, it only makes sense that tar and asphalt, with such different chemistries, are also vastly different, with different properties.
Quasars are the most luminous type of active galaxy. They emit light across the electromagnetic spectrum, produce powerful particle jets, and can radiate thousands of times the energy emitted by a galaxy like the Milky Way. The nearest quasar, called Markarian 231, is located some 600 million light-years away, but we see many more quasars the farther we look.
Scientists have identified over 1 million quasars, with the farthest one currently known lying about 13 billion light-years away. Since light takes time to travel, scientists can use light from these galaxies as a way to peer back in time to study black hole growth and galaxy evolution. Merging galaxies in the young universe may provide the fuel to power the enormous energy output of quasars, but when the feeding frenzy ends, the black hole cannot maintain it. It’s thought that quasar activity may be episodic and that this entire phase may last only about 10 million years.
Seyfert galaxies, first identified in 1943 by American astronomer Carl Seyfert, are the most common active galaxies and also exhibit the lowest energies. All Seyferts look like normal galaxies in visible light, but they emit considerable infrared radiation. When observed in the infrared, some reveal bright emission from the donut-shaped torus. Some also emit X-rays. Seyfert galaxies tend to have lower radio luminosities, although some produce radio jets.
Scientists divide Seyferts into two classes. Type I Seyfert galaxies display unusual features in their visible light that imply rapid motion near the accretion disk. Type II Seyferts show features that imply much slower motion. However, this distinction may result from different viewing angles into the centers of these galaxies.
The Hubble Space Telescope captured this image of NGC 5264, an irregular dwarf galaxy.
Irregular galaxies tend to have unusual shapes, like toothpicks, rings, or little groupings of stars. Their sizes also range from dwarf irregular galaxies, with 100 million times the Sun's mass, to large ones weighing 10 billion solar masses.
Astronomers think these galaxies’ odd shapes are sometimes the result of interactions with others. For example, one spiral galaxy passing another with a stronger gravitational pull could lose some of its material, become distorted, and morph into a new shape. Some, like gas-rich dwarf galaxies, may be new, formed by material pulled from such encounters. Or perhaps when galaxies collide, they create a larger, oddly shaped mashup. Some scientists theorize that some large irregular galaxies could represent an intermediate step between spiral and elliptical galaxies.
Irregular galaxies born from galaxy interactions or collisions typically host a mix of older and younger stars, depending on the characteristics and composition of the original galaxies. Irregular galaxies may also hold significant amounts of gas and dust – essential ingredients for making new stars.
It's expected that when our galaxy collides with Andromeda, it will form an irregular galaxy.
Black Scientists and Engineers Past and Present Enable NASA Space Telescope
The Nancy Grace Roman Space Telescope is NASA’s next flagship astrophysics mission, set to launch by May 2027. We’re currently integrating parts of the spacecraft in the NASA Goddard Space Flight Center clean room.
Once Roman launches, it will allow astronomers to observe the universe like never before. In celebration of Black History Month, let’s get to know some Black scientists and engineers, past and present, whose contributions will allow Roman to make history.
Dr. Beth Brown
The late Dr. Beth Brown worked at NASA Goddard as an astrophysicist. in 1998, Dr. Brown became the first Black American woman to earn a Ph.D. in astronomy at the University of Michigan. While at Goddard, Dr. Brown used data from two NASA X-ray missions – ROSAT (the ROentgen SATellite) and the Chandra X-ray Observatory – to study elliptical galaxies that she believed contained supermassive black holes.
With Roman’s wide field of view and fast survey speeds, astronomers will be able to expand the search for black holes that wander the galaxy without anything nearby to clue us into their presence.
Dr. Harvey Washington Banks
In 1961, Dr. Harvey Washington Banks was the first Black American to graduate with a doctorate in astronomy. His research was on spectroscopy, the study of how light and matter interact, and his research helped advance our knowledge of the field. Roman will use spectroscopy to explore how dark energy is speeding up the universe's expansion.
NOTE - Sensitive technical details have been digitally obscured in this photograph.
Sheri Thorn
Aerospace engineer Sheri Thorn is ensuring Roman’s primary mirror will be protected from the Sun so we can capture the best images of deep space. Thorn works on the Deployable Aperture Cover, a large, soft shade known as a space blanket. It will be mounted to the top of the telescope in the stowed position and then deployed after launch. Thorn helped in the design phase and is now working on building the flight hardware before it goes to environmental testing and is integrated to the spacecraft.
Sanetra Bailey
Roman will be orbiting a million miles away at the second Lagrange point, or L2. Staying updated on the telescope's status and health will be an integral part of keeping the mission running. Electronics engineer Sanetra Bailey is the person who is making sure that will happen. Bailey works on circuits that will act like the brains of the spacecraft, telling it how and where to move and relaying information about its status back down to Earth.
Learn more about Sanetra Bailey and her journey to NASA.
Dr. Gregory Mosby
Roman’s field of view will be at least 100 times larger than the Hubble Space Telescope's, even though the primary mirrors are the same size. What gives Roman the larger field of view are its 18 detectors. Dr. Gregory Mosby is one of the detector scientists on the Roman mission who helped select the flight detectors that will be our “eyes” to the universe.
Dr. Beth Brown, Dr. Harvey Washington Banks, Sheri Thorn, Sanetra Bailey, and Dr. Greg Mosby are just some of the many Black scientists and engineers in astrophysics who have and continue to pave the way for others in the field. The Roman Space Telescope team promises to continue to highlight those who came before us and those who are here now to truly appreciate the amazing science to come.
To stay up to date on the mission, check out our website and follow Roman on X and Facebook.
Make sure to follow us on Tumblr for your regular dose of space!
The image below is Lenticular galaxy NGC 4886, photographed by the Hubble Space Telescope, containing primarily old stars but no spiral arms.
Lenticular galaxies are like a cross between spiral galaxies and elliptical galaxies. They have the central bulge and disk common to spiral galaxies but no arms. But like ellipticals, lenticular galaxies have older stellar populations and little ongoing star formation.
Scientists have a few theories about how lenticular galaxies evolved. One idea suggests these galaxies are older spirals whose arms have faded. Another proposes that lenticulars formed from mergers of spiral galaxies.
Elliptical galaxies have shapes that range from completely round to oval. They are less common than spiral galaxies.
Unlike spirals, elliptical galaxies usually contain little gas and dust and show very little organization or structure. The stars orbit around the core in random directions and are generally older than those in spiral galaxies since little of the gas needed to form new stars remains. Scientists think elliptical galaxies originate from collisions and mergers with spirals
The image below is spiral galaxy M101, also known as the Pinwheel galaxy, was captured by the Hubble Space Telescope.
NASA, ESA, K. Kuntz (JHU), F. Bresolin (University of Hawaii), J. Trauger (Jet Propulsion Lab), J. Mould (NOAO), Y.-H. Chu (University of Illinois, Urbana) and STScI; CFHT Image: Canada-France-Hawaii Telescope/J.-C. Cuillandre/Coelum; NOAO Image: G. Jacoby, B. Bohannan, M. Hanna/NOAO/AURA/NSF
These galaxies resemble giant rotating pinwheels with a pancake-like disk of stars and a central bulge or tight concentration of stars. Our own Milky Way is a spiral galaxy and is actually on course to colliding with our closest neighbor, the Andromeda galaxy, also known as Messier 31 (M31) which is another spiral galaxy located about 2.5 million light years away. It's on course to collide with the Milky Way in about 5 billion years.
The spirals in a spiral galaxy can be wound tight or loose and because they are pancake-like, we often cannot see them as we observe space at a sideways angle.
Spiral galaxies are surrounded by halos, or mixtures of old stars, star clusters, and dark matter. The youngest stars form in the arms of the spiral galaxy that are more gas rich while older stars are found throughout the disc and within the bulge and halo.
Both the Milky Way and the Andromeda galaxies are a subtype known as barred spirals, which make up two-thrids of the group. They support ribbons of stars, gas, and dust that cut across their centers. Scientists think that a bar indicates that a galaxy has reached full maturity.
What are galaxies? Scientists sometimes categorize galaxies based on their shapes and physical features. Other classifications organize galaxies by the activity in their central regions – powered by a supersized black hole – and the angle at which we view them.
What are active galaxies?
Around 10% of known galaxies are active, which means their centers appear more than 100 times brighter than the combined light of their stars. They can be spiral, elliptical, or irregular. The Milky Way is not currently an active galaxy, although it likely experienced a burst of activity in the past few million years. They think this happened due to nearby supermassive black holes that are hundreds of thousands to billions of times the mass of the sun.
Active galaxies can also be categorized by their brightness in radio wavelengths. Radio-loud galaxies typically emit from both the accretion disk and the jets. Radio-quiet galaxies tend to have little-to-no emission from jets. The observed luminosity is also thought to be another aspect of our viewing angle. Jets directed more toward our line of sight, viewed “down the barrel,” appear brighter and more variable than those viewed at wider angles.
