Glossary term: Sol
Description: O Sol é a estrela que está mais próxima da Terra. Para os astrônomos, é uma estrela do tipo "G2V". Isso significa que o Sol é uma estrela de sequência principal com uma temperatura típica ("temperatura efetiva") de 5800 kelvins (K). As estrelas de sequência principal são estáveis, com a energia liberada pela fusão de hidrogênio em seu núcleo equilibrando a força interna em decorrência da gravidade. O Sol parece branco ao olho humano, pois emite muita luz em todo o espectro visível. Quando está em uma posição mais baixa no céu, o aumento da extinção atmosférica pode fazer com que o Sol pareça amarelo ou laranja, daí sua representação comum como amarelo. As estrelas variam de mais de 1.000 vezes mais brilhantes do que o Sol a cerca de 1.000 vezes mais fracas, mas as mais brilhantes são relativamente raras: o Sol é mais brilhante (e mais pesado) do que a maioria (talvez cerca de 85%) das estrelas da Galáxia.
Para os astrônomos, o Sol é interessante devido à sua proximidade, o que significa que a superfície pode ser resolvida com mais detalhes, permitindo o estudo de estruturas e fenômenos. Por exemplo, os estudos detalhados da atividade solar, que está relacionada aos campos magnéticos do Sol, podem incluir: manchas solares (áreas mais frias), erupções (flashes brilhantes de curta duração) e até mesmo ejeções de massa coronal (partículas eletricamente carregadas lançadas para longe do Sol). Os físicos também detectaram partículas elementares conhecidas como neutrinos do núcleo do Sol; essa é uma evidência direta de processos de fusão nuclear. O elemento hélio foi detectado pela primeira vez no espectro solar, daí o nome Hélio, que vem de Helios (na mitologia grega, o deus Sol).
Related Terms:
- Main Sequence
- Nuclear Fusion
- Solar Flare
- Star
- Sunspot
- Effective Temperature
- Magnetic Field
- Neutrino
- Coronal Mass Ejection (CME)
See this term in other languages
Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher The translation of this term and its definition is still awaiting approval
The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".
If you notice a factual or translation error in this glossary term or definition then please get in touch.
Related Media
Winter Haloes, by Thomas Gigl, Germany
Caption: Second place in the 2021 IAU OAE Astrophotography Contest, category Sun/Moon haloes.
Captured in Jochberg located in the famous Austrian ski-region of Tirol, this image shows multiple features related to ice halos, which are a more common appearance around the sun, due to its brightness, than the moon. External and internal reflection of sun rays from ice crystal faces and within different types of ice crystals lead to these halo related phenomena. The 22° halo encircles the sun, with two bright spots at the edge called Sundogs, Parhelia or Mock Suns observed to the left and right at the same height as the sun. The horizontal white band called the parhelic circle, named after the sun god Helios, passes through the sun and the Sundogs at the same angular elevation. An Upper tangent arc, a suncave parry arc and a lower tangent arc are also seen touching the top and bottom of the 22° halo. An upside down rainbow like arc or the circumzenithal arc is seen touching the bright supralateral arc, both of which are less frequently observed.
Credit: Thomas Gigl/IAU OAE
License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons
Sunspots
Caption: In this image the sun peppered with groups of sunspots over almost nine days between July and August 2012. The sunspots seen in this image have been sources of the solar flares and coronal mass ejections (CME). In this image particulary, the sun is approaching solar maximum in its cycle (solar cycle), where we see many spots forming along the suns' equator. These sunspots and activity are seen in the southern hemisphere, before then most of the activity was on the northern hemisphere.
Credit: NASA/SDO/HMI
credit link
License: PD Public Domain icons
Solar flare
Caption: This image shows the mid-level solar flare that was observed in March 2022 by the Solar Dynamic Observatory (SDO). The SDO observes the Sun activity, hence it shows the regions on the Sun where there is activity. A solar flare is brief brightening on the sun's surface, this particular flare is an M-class, which means that it is a tenth of the size of the most intense flares, namely the X-flares. Solar flares are barely visible with the naked eye, thus the SDO. The image here, is captured in extreme ultravoilet light that was colourized by red in the SDO, the flare appears in the upper of the solar disk.
Credit: NASA/SDO
credit link
License: PD Public Domain icons
H-alpha image of the Sun's chromosphere
Caption: This false-color image was captured with a 10-cm telescope at the Big Bear Solar Observatory (BBSO) in the United States in July 2002. It depicts the full disk of the Sun using the H-alpha emission line of hydrogen. When observed in this spectral line, the Sun's chromosphere appears particularly prominent due to hydrogen atoms emitting light at the specific wavelength. This emission produces a distinctive red color, making features such as spicules (jets of plasma that look hair-like) and plage (bright patches in the chromosphere) highly visible. Several small solar prominences can be seen protruding from the edge of the solar disk. When prominences (also known as filaments) cross the face of the disk they appear as dark threads caused by the cooler material in the prominence absorbing light. The chromosphere is also visible in the violet part of the solar spectrum due to ionized calcium showing emissions in these wavelengths.
Credit: Big Bear Solar Observatory (BBSO)/New Jersey Institut of Technology (NJIT)
credit link
License: PD Public Domain icons
Close-up view of a sunspot
Caption: This image of a sunspot was taken by the Daniel K Inouye Solar Telescope (DKIST), operated by the U.S. National Science Foundation. It was taken only in light with a wavelength of 530 nanometers, within the greenish-yellow part of the visible spectrum.
The picture reveals the detail of the spot's structure and the Sun’s photosphere. The dark central region, known as the umbra, is surrounded by a lighter area called the penumbra with radially elongated features stretching towards the umbra. Note that the umbra and penumbra here are not the same as the umbra and penumbra that occur during an eclipse.
The sunspot measures approximately 5000 kilometres in diameter, roughly equivalent to the east-west span of China. While the umbra appears black, it is actually hot and bright. It only appears dark because it is a few thousand kelvin cooler than the surrounding solar photosphere. Surrounding the sunspot, granulation patterns of plasma are visible on the photospheric surface of the Sun.
Credit: NSO/NSF/AURA
credit link
License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons
Related Activities
Measure the Solar Diameter
astroEDU educational activity (links to astroEDU website) Description: Hands-on activity to measure the Sun by using household materials.
License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons
Tags:
Hands-on
, Scales
, Observing
, Measurement
Age Ranges:
12-14
, 14-16
, 16-19
, 19+
Education Level:
Middle School
Areas of Learning:
Social Research
Costs:
Low Cost
Group Size:
Group
Skills:
Communicating information
, Constructing explanations
, Using mathematics and computational thinking
Counting Sunspots
astroEDU educational activity (links to astroEDU website) Description: Counting the Sunspots using real solar images and data.
License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons
Tags:
Hands-on
, Sunspots
, Data analysis
Age Ranges:
16-19
Areas of Learning:
Observation based
Costs:
Low Cost
Duration:
1 hour
Group Size:
Group
Skills:
Analysing and interpreting data
, Constructing explanations
, Using mathematics and computational thinking
Meet Our Neighbours: Sun
astroEDU educational activity (links to astroEDU website) Description: Explore the tactile version of our star; the Sun with household materials.
License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons
Tags:
Hands-on
, Model
, Sunspots
, Visually Impaired
, Tactile
Age Ranges:
6-8
, 8-10
, 10-12
Education Level:
Middle School
, Primary
, Secondary
Areas of Learning:
Interactive Lecture
, Modelling
Costs:
Low Cost
Duration:
1 hour
Group Size:
Group
Skills:
Analysing and interpreting data
, Developing and using models
Build a Safe Sun Viewer
astroEDU educational activity (links to astroEDU website) Description: Build a safe Sun viewer using cheap household items and learn why it is dangerous to look directly at the Sun, even briefly.
License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons
Tags:
Hands-on
, Safety
Age Ranges:
6-8
, 8-10
, 10-12
Education Level:
Primary
, Secondary
Areas of Learning:
Modelling
, Observation based
Costs:
Low Cost
Group Size:
Group
Skills:
Planning and carrying out investigations
Solar System Model
astroEDU educational activity (links to astroEDU website) Description: Make a model of the Solar System planets using household materials.
License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons
Tags:
Hands-on
, Model
, Planets
Age Ranges:
4-6
, 6-8
, 8-10
Education Level:
Pre-school
, Primary
Areas of Learning:
Modelling
Costs:
Low Cost
Duration:
30 mins
Group Size:
Group
Skills:
Analysing and interpreting data
, Asking questions
, Communicating information
, Developing and using models
