---
title: Professional astronomers often use the parsec, about 3.26 light year… — Distances and light years · tree and pragmatics
description: Professional astronomers often use the parsec, about 3.26 light years, a unit based on how stars seem to shift as Earth orbits the Sun. Who acts: Professional astronomers, stars, Earth. A sentence of the lesson «Distances and light years» of the space course of Mova's primary school with its depende
---

<!-- md -->
[Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/space/22-distances-and-light-years/13/)

<!-- crumbs -->
[home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Space](https://md.mova.elamur.ai/free/en/corpora/school/space/) / [Distances and light years](https://md.mova.elamur.ai/free/en/corpora/school/space/22-distances-and-light-years/) / 13

# Distances and light years, sentence 13

<!-- .ven lang=en -->
Professional astronomers often use the parsec, about 3.26 light years, a unit based on how stars seem to shift as Earth orbits the Sun.

<!-- .vintro -->
**Who acts:** Professional astronomers, stars, Earth · **What happens:** use, base, seem, shift, orbit · **To what, where:** parsec, unit, Sun.

<!-- .vabout -->
This is a sentence of the lesson «Distances and light years» of the space course of Mova's primary school. The page gives its syntax tree — a dependency tree in the style of Universal Dependencies — and its pragmatics clause by clause: who acts (Professional astronomers, stars, Earth), what happens, when and where, as Mova's frames read it from the tree.

## The tree {#tree}

```conllu
# sent_id = school:space:022-distances-and-light-years.lesson:13
# text = Professional astronomers often use the parsec, about 3.26 light years, a unit based on how stars seem to shift as Earth orbits the Sun.
# source = school lesson (ours)
# course = space
# lesson = 022-distances-and-light-years.lesson
# annotation = Mova annot: Rust (en) → Haiku 5.5 (medium, Batches API) patches; gates UD 2.18; agreed by treeagree rules (Stanza, Trankit, spaCy trf): R7-rel-agree ×1
1	Professional	professional	ADJ	JJ	Degree=Pos	2	amod	_	_
2	astronomers	astronomer	NOUN	NNS	Number=Plur	4	nsubj	_	_
3	often	often	ADV	RB	_	4	advmod	_	_
4	use	use	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
5	the	the	DET	DT	Definite=Def|PronType=Art	6	det	_	_
6	parsec	parsec	NOUN	NN	Number=Sing	4	obj	_	_
7	,	,	PUNCT	,	_	11	punct	_	_
8	about	about	ADV	RB	_	9	advmod	_	_
9	3.26	3.26	NUM	CD	NumForm=Digit|NumType=Card	11	nummod	_	_
10	light	light	NOUN	NN	Number=Sing	11	compound	_	_
11	years	year	NOUN	NNS	Number=Plur	6	appos	_	_
12	,	,	PUNCT	,	_	14	punct	_	_
13	a	a	DET	DT	Definite=Ind|PronType=Art	14	det	_	_
14	unit	unit	NOUN	NN	Number=Sing	6	appos	_	Agree=R7-rel-agree|Haiku=6:conj
15	based	base	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	14	acl	_	_
16	on	on	SCONJ	IN	_	19	mark	_	_
17	how	how	ADV	WRB	PronType=Int	19	advmod	_	_
18	stars	star	NOUN	NNS	Number=Plur	19	nsubj	_	_
19	seem	seem	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	15	advcl	_	_
20	to	to	PART	TO	_	21	mark	_	_
21	shift	shift	VERB	VB	VerbForm=Inf	19	xcomp	_	_
22	as	as	SCONJ	IN	_	24	mark	_	_
23	Earth	Earth	PROPN	NNP	Number=Sing	24	nsubj	_	_
24	orbits	orbit	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	21	advcl	_	_
25	the	the	DET	DT	Definite=Def|PronType=Art	26	det	_	_
26	Sun.	Sun	PROPN	NNP	Number=Sing	24	obj	_	_
```

## Pragmatics {#pragmatics}

<!-- sa -->
- form: statement
- act: assert
- voice: narrator
- polarity: none
- teacher: kept the draft

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **use** | present | Professional astronomers | the parsec |  |  |  | often *property* | vn eat-39.1 «NP V NP»: agent=Agent parsec=Patient |
| 2 | **base** | participle |  | a unit *not said here* |  |  |  |  | vn base-97.1 «NP V NP PP.source»: agent=Agent |
| 3 | **seem** | present | stars |  |  |  |  |  | vn seem-109-1-1-1 «NP V S\_INF»: agent=Theme clause=Attribute |
| 4 | **shift** | to-infinitive | stars *not said here* |  |  |  |  |  | vn caused\_calibratable\_cos-45.6.2-1 «NP V ADV-Middle»: agent=Patient |
| 5 | **orbit** | present | Earth | the Sun. |  |  |  |  | tree rules |

<!-- .note -->
One row per clause the reader finds. «not said here»: a role filled from the clause above. «roles by»: a VerbNet class and frame when one fits the verb, else the reader's rules on the tree.

<!-- div src -->

**Licence: [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/)**, as the whole of Mova corpus 0.4, of which this treebank (the agreed school, `mova-school-agreed-en.conllu`) is part. The lessons were written for Mova's primary school. Sentence `school:space:022-distances-and-light-years.lesson:13`.

**The tree:** Mova annot: Rust (en) → Haiku 5.5 (medium, Batches API) patches; gates UD 2.18; agreed by treeagree rules (Stanza, Trankit, spaCy trf): R7-rel-agree ×1. **The frames** are read from the tree by Mova's frames reader (`prag`) when this page is built, the lesson read in order, so a pronoun may be resolved from an earlier sentence.

See the [release 0.4](https://md.mova.elamur.ai/free/en/releases/0.4/).

<!-- /div -->

<!-- pn -->
- ← previous: [Distances and light years, 12](https://md.mova.elamur.ai/free/en/corpora/school/space/22-distances-and-light-years/12/)
- next →: [Distances and light years, 14](https://md.mova.elamur.ai/free/en/corpora/school/space/22-distances-and-light-years/14/)
- ↑ back to [the lesson](https://md.mova.elamur.ai/free/en/corpora/school/space/22-distances-and-light-years/)