My Science School

The term Blood Moon once was used in some sects of Christian prophecy to describe a total lunar eclipse that belonged to a tetrad of total lunar eclipses. The most recent Blood Moon – at least by this definition – took place on September 28, 2015. The next one won’t come until April 25, 2032.

The moon orbits around Earth, while Earth orbits around the sun. The moon takes about 27 days to orbit Earth and goes through regular phases in a 29.5-day cycle. The difference in these two cycles has to do with the relative positions of the sun, Earth and moon, which change during the moon's orbit.

Lunar eclipses can only happen during a full moon, when the sun fully illuminates the surface. Usually a full moon has no eclipse because the moon orbits in a slightly different plane than the Earth and the sun do. However, at times the planes coincide. Earth passes in between the moon and the sun and cuts off the sunlight, causing an eclipse.

 

Picture Credit : Google

Baade's Window is an area of the sky with relatively low amounts of interstellar "dust" along the line of sight from the Earth. This area is considered an observational "window" as the normally obscured Galactic Center of the Milky Way is visible in this direction. It is named for astronomer Walter Baade who first recognized its significance. This area corresponds to one of the brightest visible patches of the Milky Way.

Walter Baade observed the stars in this area in the mid-1940s using the 100-inch (2.5 m) Hooker telescope at Mount Wilson Observatory in California while searching for the center of the Milky Way galaxy. Up until this time the structure and location of the galactic center was not known with certainty.

In 2006, the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) conducted an astronomical survey to monitor 180,000 stars for seven days to detect extrasolar planets via the transit method.

Baade's Window is frequently used to study distant central bulge stars in visible and near-visible wavelengths of light. Important information on the internal geometry of the Milky Way is still being refined by measurements made through this "window". It is in the direction of the constellation of Sagittarius. The window is now known to be slightly "south" of the main central galaxy bulge. The window is irregular in outline and subtends about 1 degree of the sky. It is centered on the globular cluster NGC 6522.

 

Picture Credit : Google

The International Astronomical Union  (IAU) is the only internationally recognized authority for assigning astronomical designations to celestial objects and surface features on them. The purpose of this is to ensure that names assigned are unambiguous. There have been many historical star catalogues, and new star catalogues are set up on a regular basis as new sky surveys are performed. All designations of objects in recent star catalogues start with an "initialism", which is kept globally unique by the IAU. Different star catalogues then have different naming conventions for what goes after the initialism, but modern catalogs tend to follow a set of generic rules for the data formats used.

The International Astronomical Union (IAU) is the officially recognized authority in astronomy for assigning designations to celestial bodies such as stars, planets, and minor planets, including any surface features on them. In response to the need for unambiguous names for astronomical objects, it has created a number of systematic naming systems for objects of various sorts.

 

Picture Credit : Google

Since then, astronomers – who study the universe and everything in it, like planets – have used bigger and better telescopes to find rings around all of the outer gas giant planets: Jupiter, Saturn, Neptune and Uranus. These planets, unlike others in our system, consist largely of gas.

The first theory states that the rings formed at the same time as the planet. Some particles of gas and dust that the planets are made of were too far away from the core of the planet and could not be squashed together by gravity. They remained behind to form the ring system.

The second theory, and my personal favourite, is that the rings were formed when two of the moons of the planet, which had formed at the same time as the planet, somehow got disturbed in their orbits and eventually crashed into each other (an orbit is the circular path that the moon travels on around the planet). 

The other thing that all rings systems share is that they are all made of small particles of ice and rock. The smallest of these particles are no bigger than dust grains, while the largest of the particles are about 20 metres in diameter – about the size of a school hall. All the rings around the planets also contain gaps that are sometimes many kilometres wide and at first nobody could figure out why. We later learned that the gaps were caused by small moons that had gobbled up all the material in that particular part of the ring system.

 

Picture Credit : Google

Tiangong-1 is a single-module space station operated by the China National Space Administration. The module was launched in 2011 and hosted two crews of taikonauts (Chinese astronauts) in 2012 and 2013. Since China's space agency discloses less information about its missions than other space agencies, the details surrounding the space station are not widely known. 

The orbit of the space station passes over most of the civilized world, with the exclusion of northern latitudes that include the United States, Russia and Canada, as well as the extreme south of the world, including Antarctica and the tip of South Africa. However, most of the Earth is covered by water, reducing the chances of a crash in a populated area.

Tiangong-1 (whose name means "Heavenly Palace") weighs about 8.5 metric tons, and is about 34 feet long by 11 feet wide (10.4 meters by 3.4 meters). It contains an experiment module — where the astronauts live and work — and a resource module that contains propellant tanks and rocket engines.

A primary goal for the module was to help the Chinese practice space dockings, which is an important skill for nations looking to build larger space stations or to send multiple spacecraft to the moon, Mars or other locations in the solar system.

 

Picture Credit : Google

The Chang'e 1 lunar orbiter was China's first deep space mission. The program was divided into three phases: circling the Moon, landing on the Moon and returning from the Moon. The program goals were to be accomplished between 2007 and 2020.

The goal of this first mission, besides proving basic technologies and testing out several engineering systems, was to create a 3D map of the lunar surface, to analyze the distribution of certain chemicals on the lunar surface, to survey the thickness of the lunar soil, to estimate helium 3 resources, and to explore the space environment (solar wind, etc.) in near-lunar space.

The Chinese Lunar Exploration Program is designed to be conducted in four phases of incremental technological advancement: The first is simply reaching lunar orbit, a task completed by Chang'e 1 in 2007 and Chang'e 2 in 2010. The second is landing and roving on the Moon, as Chang'e 3 did in 2013 and Chang'e 4 did in 2019. The third is collecting lunar samples from the near-side and sending them to Earth, a task for the future Chang'e 5 and Chang'e 6 missions. The fourth phase consists of development of a robotic research station near the Moon's south pole. The program aims to facilitate a crewed lunar landing in the 2030s and possibly build an outpost near the south pole.

 

Picture Credit : Google

In 2009, NASA launched a spacecraft called Kepler to look for exoplanets. Kepler looked for planets in a wide range of sizes and orbits. And these planets orbited around stars that varied in size and temperature.

Kepler detected exoplanets using something called the transit method. When a planet passes in front of its star, it’s called a transit. As the planet transits in front of the star, it blocks out a little bit of the star's light. That means a star will look a little less bright when the planet passes in front of it.

When a planet passes in front of a star as viewed from Earth, the event is called a “transit”. On Earth, we can observe an occasional Venus or Mercury transit. These events are seen as a small black dot creeping across the Sun—Venus or Mercury blocks sunlight as the planet moves between the Sun and us. Kepler finds planets by looking for tiny dips in the brightness of a star when a planet crosses in front of it—we say the planet transits the star.

Once detected, the planet's orbital size can be calculated from the period (how long it takes the planet to orbit once around the star) and the mass of the star using Kepler's Third Law of planetary motion. The size of the planet is found from the depth of the transit (how much the brightness of the star drops) and the size of the star. From the orbital size and the temperature of the star, the planet's characteristic temperature can be calculated. 

 

Picture Credit : Google

Gamma Cephei Ab is an exoplanet approximately 45 light-years away in the constellation of Cepheus (the King). The planet was confirmed to be in orbit around Gamma Cephei A in 2002, but was first suspected to exist around 1988 (making this planet arguably the first true exoplanet discovered).

The first indications of Gamma Cephei Ab were reported in July 1988. The planet was tentatively identified by a Canadian team of astronomers, which was led by Bruce Campbell, Gordon Walker, and Stephenson Yang, while its existence was also announced by Anthony Lawton and P. Wright in 1989. Though not confirmed, this would have been the first true discovery of an extrasolar planet, and it was hypothesized based on the same radial velocity technique later used successfully by others. However, the claim was retracted in 1992 due to the quality of the data not being good enough to make a solid discovery.

On September 24, 2002, Gamma Cephei Ab was finally confirmed. The team of astronomers (including William D. Cochran, Artie P. Hatzes, et al.) at the Planetary Systems and their Formation Workshop announced the preliminary confirmation of a long-suspected planet Gamma Cephei Ab with a minimum mass of 1.59 MJ (1.59 times that of Jupiter). The parameters were later recalculated when direct detection of the secondary star Gamma Cephei B allowed astronomers to better constrain the properties of the system.

 

Picture Credit : Google

Going by its name, it might be easy to guess where interstellar space exists – ‘Inter’ means in between, and ‘Stellar’ refers to stars. This would mean interstellar space is that part of space that exists between stars. However, that is not true.

Bye, bye heliosphere, hello interstellar

Interstellar space begins where the Sun’s constant flow of material and magnetic field stops affecting its surroundings. This place is called the heliopause.

The heliopause marks the end of the heliosphere, the region created by our Sun. the heliosphere, which is like a bubble, is created by the Sun sending a constant flow of particles and a magnetic field out into space at over 6,70,000 miles per hour. This stream of particles sent out by the Sun is called solar wind.

Like the wind on Earth, the solar wind pushes against any particles around it. This means the solar wind is constantly pushing against particles from other stars. The heliosphere exists till such a place where the solar wind can keep the foreign particles out. After this place, the interstellar space begins.

How do we know if we are in interstellar space?

Well, clearly defined boundaries for space are mentioned in paper, but it can’t really be seen with the naked eye. Interstellar space cannot be experienced on Earth. So far only probes sent by NASA have been able to identify interstellar space.

The probes would help us know we are in interstellar space when there is an increase in ‘cold’ particles around them. This is because, inside the heliosphere, the solar particles are hot but less concentrated. Outside the heliosphere, the particles are highly concentrated but are much colder.

The probes would also know they are in interstellar space when they identify a magnetic field that does not originate from our Sun.

Two probes sent by NASA – Voyager 1 and Voyager 2 – are the only ones to reach interstellar space.

 

Picture Credit : Google

You would have likely seen a lightning at one point of time or another. Did you know that the electrical discharges as a result of imbalances between storm clouds and the ground, or within the clouds themselves, is what is referred to as a lightning? These normally occur within clouds.

When a storm is occurring, the colliding particles of rain, ice or snow inside these storm clouds change the balance between the clouds and the ground. Whereas the lower reaches of the clouds often become negatively charged, the objects on the ground, including the Earth, become positively charged.

The resulting lightning passes current between the two charges and is nature’s way of normalizing the imbalance.

Lightning are extremely hot and it is this heat that causes the surrounding air to expand and vibrate in a rapid manner. This results in the thunder that we hear shortly after seeing a lightning flash. Lightnings are surely spectacular sights, but they are also deadly. There are thousands who die by lightning strikes every year, despite the fact that nearly nine out of 10 people who are hit by a lightning survive. The thousands of survivors are left with a variety of symptoms, ranging from memory loss and weakness to numbness.

 

Picture Credit : Google

TELESCOPES

A telescope is an instrument that makes distant objects appears closer, allowing the viewer to see details that are not visible with the naked eye. Terrestrial telescopes are used for spotting wildlife (binoculars are made up of two telescopes, one for each eye), on gun sights and in periscopes. Astronomical telescopes are used to study objects in space. Terrestrial telescopes and most astronomical telescopes are optical telescopes, which collect light coming from distant objects and use it to produce images of the objects.

Italian scientist Galileo used the first astronomical telescope in 1609, with which he discovered moons around Jupiter.

There are two main types of optical telescope - refracting telescopes and reflecting telescopes. In a refracting telescope, a convex (bulging) lens collects light from the distant object and focuses it to form an image of the object. This image is very small, but is much larger than the image formed in the human eye. In a reflecting telescope, a concave (dish-shaped) mirror collects the light from the object and focuses it to form the image. Larger telescopes are nearly always reflecting telescopes because large mirrors are easier to manufacture than large lenses.

The Keck telescope in Hawaii has a main mirror 10 metres across. It is housed in a special building called an observatory.

The larger the lens of a refracting telescope or the mirror of a reflecting telescope, the brighter the image of the object observed, and the fainter the objects that can be seen with the telescope. The image is viewed with an eyepiece lens, which works like a magnifying glass to make it appear much larger.

RADIO TELESCOPES

Objects in space, such as stars and galaxies, do not just give off light. They also give off radiation from other parts of the electromagnetic spectrum, such as infrared radiation, radio waves, X-rays and ultraviolet radiation. These can show up objects that are otherwise invisible. They cannot be seen with ordinary optical telescopes, so special telescopes are needed.

Radio telescopes have a huge dish that acts as a reflector, collecting radio waves and focusing them on to a detector. Radio astronomy has allowed the discovery of new celestial objects, such as pulsars.

SPACE TELESCOPES

The Earth’s atmosphere stops many types of radiation from reaching the surface. To study these sorts of radiation, space telescopes must be launched into Earth orbit. They need special mirrors to reflect and focus the radiation, and electronic detectors to record the images formed, which are radioed back to Earth. Optical telescopes also benefit from being in orbit because the atmosphere distorts light rays as they pass through it. The Hubble Space Telescope, launched by space shuttle in 1990, is the most complex space telescope so far. It can detect visible light, infrared and ultraviolet rays.

The Hubble Space Telescope can see 10 times more detail than Earth-based telescopes and objects 50 times as faint. Solar panels provide its power. Images are transmitted via antennae.

Picture Credit : Google

Every night many of us eagerly wait for the Moon to rise. But each night, the Moon looks slightly different from what it did the previous night. Sometimes the Moon looks like a narrow crescent, while at other times it looks like a big circle. On some nights, you might not see the Moon at all. These different shapes of the Moon that we see at different times of the month are called the Moon’s phases.

Does the Moon really change shapes?

No, the Moon does not change its shape. But it appears different to us because our view of the Moon changes based on how much of the Moon is illuminated by the Sun. The Moon does not produce its own light. It depends entirely on the Sun for light, like all the planets in our solar system. The Sun’s light comes from one direction, thereby illuminating one half of the Moon that is facing the sun, while the other half remains in darkness.

On Earth, our view of the illuminated part of the Moon changes each night depending on where the Moon in its orbit around the Earth. When we see the completely illuminated part of the Moon, that phase of the Moon is known as a Full Moon.

Each night following the Full Moon, as the Moon orbits around the Earth, we start to see less of the Moon illuminated by the Sun until we see no Moon at all. This phase is called the New Moon, when the far side of the Moon is facing the Sun and the side facing the Earth is dark.

The eight phases

According to NASA, the Moon has eight phases which we see one after the other as the Moon completes its cycle around the Earth. It takes the Moon 27 days to orbit Earth. The eight phases are:

New – When we cannot see the Moon at all

Waxing Crescent – When we see the Moon as a think crescent opening to the left. Waxing is when the Moon is growing with light.

First Quarter – When we see the first quarter phase of the Moon which appears to us as a Half Moon.

Waxing Gibbous – The phase between Half and Full Moon, when most part of the Moon can be seen.

Full – When we see the Moon completely illuminated.

Waning Gibbous – The phase between Half and Full Moon. Now, the view of the Moon is getting smaller.

Third Quarter – The third quarter of the Moon, seen as Half Moon on Earth. In this, the opposite half of the First Quarter is illuminated and visible.

Waning Crescent – When we see the Moon as a thin crescent opening to the right.

 

Picture Credit : Google