Comet Leonard

A universe in motion seen from the International Space Station during a night pass over Earth.

(@ wonderofscience on Twitter)

Timelapse created from images courtesy of the Earth Science and Remote Sensing Unit, NASA Johnson Space Center(ISS061-E-110520-111341 eol.jsc.nasa.gov).

okay so. does anybody remember this creepy image? and yes, it's real, by the way.

this is barnard 68, a dark nebula that does not allow light to pass through. it's quite close to us too, and so dense that the stars behind it can't be observed from earth. it's just a molecular cloud, though! looks like a tear in the fabric of existence itself, but it's just a very big dark blob of gas floating in space. barnard 68 is often confused with the boötes void, which is also referred to as "the great nothing".

what's that, you say? oh, well... it's a region in space about 330 million light years wide. this is about 0.27% of the width of the entire observable universe. an area this large is expected to have around 2000 galaxies, but this one only has 60. everything else is just... dead, empty space.

okay, what if i told you that we actually are within a void ourselves? it's called the kbc void. another name is uhh.. local hole. anyways. it's theoretically the largest void we know of, about 2 billion light years across. it's extremely speculative, but it might account for the hubble tension; that is, shit seems to be flying away from us faster than it should be.

some people claim other things cause the discrepancy in our observations of the hubble constant, some debate whether it's consistent with our current cosmological model at all. it isn't completely accepted by the astrophysics community, but it's not a preposterous claim to make either. i personally think it's cool.

maybe shit does fly away faster from us because we live in a local hole. the rest of the universe is an intergalactic party, and we're not invited.

Galactic center of Milky Way © cosmic_background

Rainer Maria Rilke, from Where Silence Reigns: Selected Prose; "An Experience,"

Saturn in near-infrared

cancel your plans we’re thinking about the pale blue dot voyager pic tonight

HOW DO ASTRONOMERS DETECT EXOPLANETS AND DETERMINE IF THEY COULD SUPPORT LIFE??

Blog#335

Wednesday, September 27th, 2023

Welcome back,

On March 21, NASA announced the confirmation of the 5,000th planet outside our Solar System. From scorching-hot gas giants nestled near their parent star to rocky worlds that may host water on their surface, there’s a variety for scientists to study.

But finding these strange new worlds is a science in itself.

We’ve only been able to definitively detect planets of any kind for a few decades, and even at that, there are challenges in detecting such a small object at that distance in even the most powerful telescopes.

Inverse spoke with Marie-Eve Naud, an exoplanet researcher and outreach coordinator for the University of Montreal’s Institute for Research on Exoplanets, to tell us more about how astronomers find these worlds and the considerations for each method.

While there are numerous methods, the ones cited below are the most common.

THE TRANSIT METHOD

Astronomers have discovered most exoplanets using the transit method, notably with NASA's Kepler telescope launched in 2009. This method observes planets as they pass in front of their stars, causing a slight dimming of starlight, which photometers can detect. This approach works best in space due to minimal atmospheric interference, favored by missions like ESA's Cheops and NASA's TESS.

To confirm exoplanets, multiple transits are necessary to rule out sunspots or dust as causes of light fluctuations. Typically, two or three transits are required to gather substantial data.

Once a planet is detected, astronomers can estimate its radius, while mass is often determined through the radial velocity method. The combination of mass and radius helps classify a planet as rocky or gaseous, impacting its potential habitability.

Factors like proximity to an active star and radiation levels also affect habitability assessments, as seen with TRAPPIST-1's uncertain habitability despite hosting seven Earth-sized planets in its habitable zone.

RADIAL-VELOCITY METHOD

The radial velocity method is commonly used to discover planets, particularly with instruments like HARPS at the European Southern Observatory’s La Silla 3.6m telescope in Chile.

Planets and stars both orbit around their center of mass. A star with a planet exhibits a slight motion. Multiple planets can lead to complex motions.

This method involves analyzing the star's spectrum. When the star approaches, its light shifts towards red due to compression. When it moves away, the light shifts towards blue.

The planet's motion slightly affects the star's spectrum, creating a "barcode" of the star.

The first detection of a planet around a Sun-like star using this method was in 1995 when Didier Queloz and Michel Mayor found 51 Pegasi b. Prior to that, in 1992, planets were detected around pulsar PSR B1257+12, using changes in the pulsar's radio signal. This showcases the diverse scientific approaches to discovering distant worlds.

Originally published on www.inverse.com

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