Nhasi, mweya wezuva unopisa uye unotonhora.

Panguva yevanhu vanhu vakatarisa pasi uye vakaona galaxy iyo tinogaramo. Nhasi, munhu mumwe muzana matatu panyika haagoni kuona Milky Way kubva kumusha. Iyi nyaya inotidzidzisa kuti tikwanise kuverenga nyika, uye kuti tinzwisise kuti chii chatinenge tarasikirwa.

Zvinhu zvepasi zvinonzi ndezvinyorwa zvakakura zvikuru. Kutonhora kwezuva kuri kukonzera kuti zvivharwe.

Ona

Onai chiedza kubva paguta rimwe chete uye munogona kuona zviuru zvezviratidzo. Kubva panzvimbo yakaoma, kure neguta, unogona kuona mamiriyoni ezviedza, uye Milky Way inotenderera pasi rose sechiedza.

Chimwe chinhu chinonzi light pollution: magetsi akagadzirwa nevanhu anobuda kumusoro uye anoita kuti nyika iite sekuti iri kupisa. Ichi chiedza chinobvisa zvitanhatu zvinotsvuka.

Dzvanya pane slider mudziyo kubva ku 1 (a chaizvo mavara nzvimbo) kuti 9 (mugwagwa shure). The stars are real: they come from a catalogue of the 9,000 or so brightest stars in the sky. Ona kuti vashoma sei vanodzokera.

Izvi hazvisi chete nezvekutarisa zvitadzo. Nekudaro, magetsi ezuva anokonzera kukuvadza kwezvisikwa zvinofamba kana kutamba munguva yechiedza, uye zvinoparadza simba nekuita kuti zviite sekuti zviri kupisa nyika. Izvi zvinobatanidza kune yedu Red Initiative uye Light Initiative yekuchengetedza kwezuva.

_Zvinyorwa

Astronomers vanoongorora kutonhora ne magnitudes. Icho chiyero chinoenda kumashure: zvitaera zvinotsvuka zvine mazita akafanana.

• Sirius, iyo yakanakisisa nhamba yezviratidzo zvezuva, ine simba rekuti -1.5.
• Zvita zvinotyisa zvikuru izvo vanhu vazhinji vanogona kuona kubva panzvimbo dzisina mvura ndezvemasimba anenge 6 kusvika 7.
• Mumigwagwa, iyo limit inogona kunge iri magnitude 4 kana yakasimba.

The Bortle scale, yakaburitswa naamateur astronomer John Bortle mu2001, inotora marudzi epasi mumarudzi mana. Ichi chikwata chinouya neyakajairika yakaderera-inoonekwa magnitude:

Bortle class	Kutaura	Zvita
1	Excellent dark site	7.6 kusvika ku8.0
3	Runyararo rwenyika	6.6 kusvika ku7.0
5	Suburban sky	5.6 kusvika ku6.0
7	Suburban / Urban transition	4.6 kusvika ku5.0
9	Chiedza chemugwagwa	4.0 pakanaka

Nekuti pane zvitaera zvakawanda zvakaomarara kupfuura zvinotsvenesa, chero kuwanda kwaunorasikirwa nahwo kunochengeta akawanda. In the Yale catalogue, about 5,000 stars are brighter than magnitude 6, but only about 500 are brighter than magnitude 4.

A 2016 world atlas yakawana kuti kupfuura 80% yevanhu, uye kupfuura 99% yevanhu muUnited States neEurope, vanorarama pasi pezuva rakaomarara.

Munyori

Magnitude i logarithmic. Kune zvitanhatu zvitanhatu zvine ma fluxes F₁ uye F₂:

m₁ − m₂ = −2.5 · log₁₀(F₁ / F₂)

Chimwe chinhu chine 5 magnitude icho chiri chikamu che100 mu flux, saka imwe magnitude icho chinonzi chikamu che100^(1/5) ≈ 2.512.

Nei zviratidzo zvinowedzera zvakanyanya? Kana zvitanhatu zvaive zvakaparadzwa zvakaenzana pasi rese, zvese zvine simba rimwe chete, huwandu hwezvitanhatu zviri nani pane m-madhigirii hwaizokura se10^(0.6 m): pamusoro pemakore mana zvitanhatu zvakawanda zvezvitanhatu kune chero hukuru hwakaderera. Iyo yakazara galaxy haina kuumbwa zvakafanana, saka kuwanda kwacho kunoonekwa kuri pasi pechiyero chemasimba anosvika makumi matatu nemana pazviviri. Unogona kuongorora izvi nekutarisa zvikamu zvemabhuku ezvinyorwa mudata rekushandisa.

Kutonhora kwenyika kunowedzera background ine simba rayo. Nhare inoratidza chete kana iri kuratidzwa zvakakwana kubva panzvimbo yepasi, saka simba rakanaka renyika rinowedzera huwandu hwekurambidza. Bortle zvinorambidzwa ndezvisiri-zvakajeka zvinotarisana nevanhu, kwete pfungwa dzenyama, uye yako yese mibairo inoenderana nemaziso ako, nekuchinja kwezuva uye nguva.

Chii chinoshanda pakudzivirira mhepo yakasviba, zvichienderana nemamiriro ekunze eDarkSky International: edza chete izvo zvinoda mweya, chete kana zvada mweya, kwete zvakajeka kupfuura zvinodiwa, kuratidzwa pasi nekuvharwa kwese, uye mune dzakachena mavara (pasi pezuva rinopisa).